https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&feed=atom&action=historyPassages of Electron Beams - Revision history2024-03-29T00:59:39ZRevision history for this page on the wikiMediaWiki 1.16.0https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=10733&oldid=prevSchriste at 17:26, 22 August 20182018-08-22T17:26:53Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Tim Bastian</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Tim Bastian</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|next_nugget = <del class="diffchange diffchange-inline">Re-acceleration and Hard X-rays</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|next_nugget=<ins class="diffchange diffchange-inline">{{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::194]]}}</ins></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|previous_nugget =[[<del class="diffchange diffchange-inline">Kappa Distribution</del>]]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|previous_nugget=<ins class="diffchange diffchange-inline">{{#ask: [[Category:Nugget]] </ins>[[<ins class="diffchange diffchange-inline">RHESSI Nugget Index::192</ins>]]<ins class="diffchange diffchange-inline">}}</ins></div></td></tr>
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</table>Schristehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5675&oldid=prevHhudson at 21:23, 11 February 20132013-02-11T21:23:16Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = Re-acceleration and Hard X-rays</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = Re-acceleration and Hard X-rays</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|previous_nugget =[[Kappa <del class="diffchange diffchange-inline">Distributions</del>]]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|previous_nugget =[[Kappa <ins class="diffchange diffchange-inline">Distribution</ins>]]</div></td></tr>
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</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5674&oldid=prevHhudson at 21:07, 11 February 20132013-02-11T21:07:51Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|name = Nugget</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|name = Nugget</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|title = Passages of Electron Beams</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|title = Passages of Electron Beams</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|number = <del class="diffchange diffchange-inline">194</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|number = <ins class="diffchange diffchange-inline">193</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Bin Chen</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Bin Chen</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Tim Bastian</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Tim Bastian</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5661&oldid=prevHhudson at 15:13, 11 February 20132013-02-11T15:13:06Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|next_nugget = <del class="diffchange diffchange-inline">Beams </del>and <del class="diffchange diffchange-inline">Waves</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|next_nugget = <ins class="diffchange diffchange-inline">Re-acceleration </ins>and <ins class="diffchange diffchange-inline">Hard X-rays</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget =[[Kappa Distributions]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget =[[Kappa Distributions]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>}}</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>}}</div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5658&oldid=prevBinChen at 10:26, 11 February 20132013-02-11T10:26:44Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[1] [<del class="diffchange diffchange-inline">https</del>://<del class="diffchange diffchange-inline">science</del>.<del class="diffchange diffchange-inline">nrao</del>.edu/<del class="diffchange diffchange-inline">facilities</del>/<del class="diffchange diffchange-inline">vla Karl G</del>. <del class="diffchange diffchange-inline">Jansky Very Large Array </del>The Expanded Very Large Array: A New Telescope for New Science]. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[1] [<ins class="diffchange diffchange-inline">http</ins>://<ins class="diffchange diffchange-inline">adsabs</ins>.<ins class="diffchange diffchange-inline">harvard</ins>.edu/<ins class="diffchange diffchange-inline">abs</ins>/<ins class="diffchange diffchange-inline">2011ApJ</ins>.<ins class="diffchange diffchange-inline">..739L...1P </ins>The Expanded Very Large Array: A New Telescope for New Science]. </div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/2013ApJ...763L..21C Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/2013ApJ...763L..21C Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy]</div></td></tr>
</table>BinChenhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5657&oldid=prevBinChen at 10:22, 11 February 20132013-02-11T10:22:56Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded [<del class="diffchange diffchange-inline">https</del>://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array] (VLA; Ref. [1]).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded [<ins class="diffchange diffchange-inline">http</ins>://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array] (VLA; Ref. [1]).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>See also our earlier Nugget on [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/A_New_Day_Dawns the EOVSA array].</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>See also our earlier Nugget on [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/A_New_Day_Dawns the EOVSA array].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td></tr>
</table>BinChenhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5656&oldid=prevBinChen at 10:20, 11 February 20132013-02-11T10:20:53Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded (Ref. [1]).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded <ins class="diffchange diffchange-inline">[https://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array] </ins>(<ins class="diffchange diffchange-inline">VLA; </ins>Ref. [1]).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>See also our earlier Nugget on [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/A_New_Day_Dawns the EOVSA array].</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>See also our earlier Nugget on [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/A_New_Day_Dawns the EOVSA array].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td></tr>
</table>BinChenhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5655&oldid=prevBinChen at 10:08, 11 February 20132013-02-11T10:08:07Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|number = 194</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|number = 194</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Bin Chen</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Bin Chen</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|second_author = </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|second_author = <ins class="diffchange diffchange-inline">Tim Bastian</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 11</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = Beams and Waves</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = Beams and Waves</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Surprisingly, no trace of loop-like structures can be found along the type-IIIdm-burst trajectories against the background in any SDO/AIA EUV filters, implying that the column emission measure of the type-IIIdm-emitting loops is too small to result in detectable emission or absorption relative to the background. With the knowledge of the plasma density inside the flux tubes, the upper limit of the diameter of each electron-beam-conducting tube can be constrained to be only a few tens of kilometers. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Surprisingly, no trace of loop-like structures can be found along the type-IIIdm-burst trajectories against the background in any SDO/AIA EUV filters, implying that the column emission measure of the type-IIIdm-emitting loops is too small to result in detectable emission or absorption relative to the background. With the knowledge of the plasma density inside the flux tubes, the upper limit of the diameter of each electron-beam-conducting tube can be constrained to be only a few tens of kilometers. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We conclude that these tubes are ultra-thin and occupied with over-dense cool plasmas.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We conclude that these tubes are ultra-thin and occupied with over-dense cool plasmas.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>In such a situation radiation at <del class="diffchange diffchange-inline">the harmonic of the plasma frequency </del>can escape <del class="diffchange diffchange-inline">more </del>easily <del class="diffchange diffchange-inline">than the fundamental</del>, a suggestion made by Arnold Benz.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>In such a situation <ins class="diffchange diffchange-inline">plasma </ins>radiation at <ins class="diffchange diffchange-inline">decimetric wavelengths </ins>can escape easily <ins class="diffchange diffchange-inline">across these thin loops</ins>, a suggestion made by Arnold Benz.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Furthermore, the multitudes of discrete electrons beams linking to the reconnection region are observed to have access to spatially distinct flux tubes in < 1 s, which indicates that the reconnection region likely consists of a large number of discrete reconnection sites in a localized spatial volume. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Furthermore, the multitudes of discrete electrons beams linking to the reconnection region are observed to have access to spatially distinct flux tubes in < 1 s, which indicates that the reconnection region likely consists of a large number of discrete reconnection sites in a localized spatial volume. </div></td></tr>
</table>BinChenhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5651&oldid=prevHhudson: links and minor edits2013-02-10T22:13:53Z<p>links and minor edits</p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>They may carry a significant amount of magnetic energy released and could therefore play a key role in flare physics. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>They may carry a significant amount of magnetic energy released and could therefore play a key role in flare physics. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One method to probe these beams is through their radio signature: [http://www.lesia.obspm.fr/cesra/highlights/highlight08-1.html type III radio bursts]. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>One method to probe these beams is through their radio signature: [http://www.lesia.obspm.fr/cesra/highlights/highlight08-1.html type III radio bursts]. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Type III radio bursts are emitted at the fundamental or harmonic of the local electron plasma frequency, f<sub>pe</sub>~9n<sub>e</sub><sup>1/2</sup> kHz, where n<sub>e</sub> is the electron number density. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Type III radio bursts are emitted at the fundamental or harmonic of the local electron <ins class="diffchange diffchange-inline">[http://en.wikipedia.org/wiki/Plasma_(physics) </ins>plasma frequency<ins class="diffchange diffchange-inline">]</ins>, f<sub>pe</sub>~9n<sub>e</sub><sup>1/2</sup> kHz, where n<sub>e</sub> is the electron number density. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded [<del class="diffchange diffchange-inline">https://science</del>.<del class="diffchange diffchange-inline">nrao.edu/facilities/vla Karl G. Jansky Very Large Array] (</del>[http://<del class="diffchange diffchange-inline">adsabs</del>.<del class="diffchange diffchange-inline">harvard</del>.edu/<del class="diffchange diffchange-inline">abs</del>/<del class="diffchange diffchange-inline">2011ApJ</del>.<del class="diffchange diffchange-inline">..739L...1P Perley et al. 2011</del>]<del class="diffchange diffchange-inline">)</del>. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded <ins class="diffchange diffchange-inline">(Ref. </ins>[<ins class="diffchange diffchange-inline">1])</ins>.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">See also our earlier Nugget on </ins>[http://<ins class="diffchange diffchange-inline">sprg</ins>.<ins class="diffchange diffchange-inline">ssl.berkeley</ins>.edu/<ins class="diffchange diffchange-inline">~tohban</ins>/<ins class="diffchange diffchange-inline">wiki/index</ins>.<ins class="diffchange diffchange-inline">php/A_New_Day_Dawns the EOVSA array</ins>].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>With this capability an image of the radio emission can be produced at each frequency and time, over a substantial frequency range.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">In the RHESSI framework this is termed ''imaging spectroscopy.''</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Here we report (Ref. <ins class="diffchange diffchange-inline">[2]</ins>) the first use of this technique to trace electron beams in the low corona through observations of type III bursts at decimeter wavelengths.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Here we report (Ref. <del class="diffchange diffchange-inline">1</del>) the first use of this technique to trace electron beams in the low corona through observations of type III bursts at decimeter wavelengths.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[File:193f1_VLA.jpg|center|thumb|600px|Karl G. Jansky Very Large Array. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[File:193f1_VLA.jpg|center|thumb|600px|Karl G. Jansky Very Large Array. The VLA has been recently upgraded with state-of-art receivers and electronics, enabling dynamic imaging spectroscopic observations of the Sun.]]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The VLA has been recently upgraded with state-of-art receivers and electronics, enabling dynamic imaging spectroscopic observations of the Sun.]]</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Trajectories of electron beams and their place of origin ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Trajectories of electron beams and their place of origin ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Type IIIdm bursts were observed between 1.0-1.5 GHz (λ=20-30 cm) in association with a coronal jet during the aftermath of a GOES class M1.8 <del class="diffchange diffchange-inline">SXR </del>flare (Figure 1B) <del class="diffchange diffchange-inline">on 2011 November 5 by the VLA</del>. Figure 1 shows the jet (panel A) and the cross-power dynamic spectra of the type IIIdm bursts (panel C-D). Each bright vertical or nearly-vertical feature in the dynamic spectra represents an individual type IIIdm burst. Each pixel of the bursts in the dynamic spectrum was imaged and the emission centroid location <del class="diffchange diffchange-inline">was fit </del>with high accuracy owing to the <del class="diffchange diffchange-inline">high </del>signal-to-noise of <del class="diffchange diffchange-inline">these </del>bursts. At any given time, <del class="diffchange diffchange-inline">type-IIIdm-</del>burst centroids as a function of frequency <del class="diffchange diffchange-inline">manifest as </del>a well-defined trajectory, <del class="diffchange diffchange-inline">showing </del>the passage of an electron beam in the corona during the 100-ms integration (Figure 2B-G). Figure 2A shows a superposition of all the type-IIIdm-burst centroids observed during the ~2-min bursting period. They all fall within a narrow envelope with the high frequency ends (high density, thus low coronal heights) originating near the location of the EUV jet and the HXR foot-points. For bursts that are temporally-resolved (Figure 2B-G), the emission drifts from high to low frequencies with a rate of 0.3-1 GHz/s, indicating that the electron beams were propagating upward in the corona with a speed of ~0.3c.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Type IIIdm bursts were observed <ins class="diffchange diffchange-inline">at the VLA, </ins>between 1.0-1.5 GHz (λ=20-30 cm)<ins class="diffchange diffchange-inline">, </ins>in association with a </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=83 </ins>coronal jet<ins class="diffchange diffchange-inline">] </ins>during the aftermath of a GOES class M1.8 <ins class="diffchange diffchange-inline">soft X-ray </ins>flare (Figure 1B) <ins class="diffchange diffchange-inline">SOL2011-11-05</ins>.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 1 shows the jet (panel A) and the cross-power dynamic spectra of the type IIIdm bursts (panel C-D). </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Each bright vertical or nearly-vertical feature in the dynamic spectra represents an individual type IIIdm burst. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Each pixel of the bursts in the dynamic spectrum was imaged<ins class="diffchange diffchange-inline">, </ins>and the emission centroid location <ins class="diffchange diffchange-inline">determined </ins>with high accuracy owing to the <ins class="diffchange diffchange-inline">excellent </ins>signal-to-noise <ins class="diffchange diffchange-inline">ratio </ins>of <ins class="diffchange diffchange-inline">such </ins>bursts <ins class="diffchange diffchange-inline">as observed by the VLA</ins>. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>At any given time, <ins class="diffchange diffchange-inline">the </ins>burst centroids as a function of frequency <ins class="diffchange diffchange-inline">show </ins>a well-defined trajectory, <ins class="diffchange diffchange-inline">revealing </ins>the passage of an electron beam in the corona during the 100-ms integration (Figure 2B-G). </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Figure 2A shows a superposition of all the type-IIIdm-burst centroids observed during the ~2-min bursting period. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>They all fall within a narrow envelope with the high frequency ends (high density, thus low coronal heights) originating near the location of the EUV jet and the HXR foot-points. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>For bursts that are temporally-resolved (Figure 2B-G), the emission drifts from high to low frequencies with a rate of 0.3-1 GHz/s, indicating that the electron beams were propagating upward in the corona with a speed of ~0.3c.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The close <del class="diffchange diffchange-inline">spatiotemporal </del>association of the type-IIIdm-burst trajectories and the HXR footpoints (Figure 1E, 2B-G) suggests that <del class="diffchange diffchange-inline">the </del>X-ray-producing downward-propagating electron beams and the type-IIIdm-emitting upward-propagating electron beams originate from a common energy release site, which is located in the low corona between the HXR footpoints and the highest-frequency type-IIIdm-burst sources, at a height of a few to ~15 Mm.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The close <ins class="diffchange diffchange-inline">spatio-temporal </ins>association of the type-IIIdm-burst trajectories and the HXR footpoints (Figure 1E, 2B-G) suggests that X-ray-producing downward-propagating electron beams and the type-IIIdm-emitting upward-propagating electron beams originate from a common energy release site, which is located in the low corona between the HXR footpoints and the highest-frequency type-IIIdm-burst sources, at a height of a few to ~15 Mm.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><gallery widths=<del class="diffchange diffchange-inline">500px </del>heights=300px></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><gallery widths=<ins class="diffchange diffchange-inline">400px </ins>heights=300px></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>File:193f2.jpg|'''Figure 1''': (A) Composite image of AR 11339 from SDO/AIA. (B) GOES SXR flux. Vertical lines indicate the time when the coronal jet occurred. (C-D) VLA dynamic spectra in which type IIIdm bursts are present. (E) VLA radio (blue) and RHESSI 12-25 keV HXR (red) light curves during the radio bursts.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>File:193f2.jpg|'''Figure 1''': (A) Composite image of AR 11339 from SDO/AIA. (B) GOES SXR flux. Vertical lines indicate the time when the coronal jet occurred. (C-D) VLA dynamic spectra in which type IIIdm bursts are present. (E) VLA radio (blue) and RHESSI 12-25 keV HXR (red) light curves during the radio bursts.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>File:193f3.jpg|'''Figure 2''': (A) Emission centroids of all type IIIdm bursts observed during the ~2-min bursting period, colored from blue to red in increasing frequencies. Red contours are RHESSI HXR emission. (B-C) and (D-G) show emission centroids of two temporally resolved type IIIdm bursts.</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>File:193f3.jpg|'''Figure 2''': (A) Emission centroids of all type IIIdm bursts observed during the ~2-min bursting period, colored from blue to red in increasing frequencies. Red contours are RHESSI HXR emission. (B-C) and (D-G) show emission centroids of two temporally resolved type IIIdm bursts.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div></gallery></div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div></gallery></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Ultra-thin flux tubes and nature of the reconnection region ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Ultra-thin flux tubes and nature of the reconnection region ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The electron number density n<sub>e</sub> and its variation along the type-IIIdm-emitting loops (or flux tubes) is immediately known since it is directly related to the plasma frequency or its harmonic, which is 3.3-7x10<sup>9</sup> cm<sup>-3</sup> assuming harmonic emission. The best-fit density scale height L<sub>n</sub>=n<sub>e</sub>(-dn<sub>e</sub>/dh)<sup>-1</sup> of the flux tubes is ~40 Mm, corresponding to a temperature of 0.8 MK under the assumption of hydrostatic equilibrium. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The electron number density n<sub>e</sub> and its variation along the type-IIIdm-emitting loops (or flux tubes) is immediately known since it is directly related to the <ins class="diffchange diffchange-inline">[http://en.wikipedia.org/wiki/Plasma_(physics) </ins>plasma frequency<ins class="diffchange diffchange-inline">] </ins>or its harmonic, which is 3.3-7x10<sup>9</sup> cm<sup>-3</sup> assuming harmonic emission. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The best-fit density scale height L<sub>n</sub>=n<sub>e</sub>(-dn<sub>e</sub>/dh)<sup>-1</sup> of the flux tubes is ~40 Mm, corresponding to a temperature of 0.8 MK under the assumption of hydrostatic equilibrium. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Surprisingly, no trace of loop-like structures can be found along the type-IIIdm-burst trajectories against the background in any SDO/AIA EUV filters, implying that the column emission measure of the type-IIIdm-emitting loops is too small to result in detectable emission or absorption relative to the background. With the knowledge of the plasma density inside the flux tubes, the upper<del class="diffchange diffchange-inline">-</del>limit of the diameter of each electron-beam-conducting tube can be constrained to be only a few tens of kilometers. We conclude that these tubes are ultra-thin and occupied with over-dense cool plasmas. <del class="diffchange diffchange-inline"> </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Surprisingly, no trace of loop-like structures can be found along the type-IIIdm-burst trajectories against the background in any SDO/AIA EUV filters, implying that the column emission measure of the type-IIIdm-emitting loops is too small to result in detectable emission or absorption relative to the background. With the knowledge of the plasma density inside the flux tubes, the upper limit of the diameter of each electron-beam-conducting tube can be constrained to be only a few tens of kilometers. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>We conclude that these tubes are ultra-thin and occupied with over-dense cool plasmas.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">In such a situation radiation at the harmonic of the plasma frequency can escape more easily than the fundamental, a suggestion made by Arnold Benz.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Furthermore, the multitudes of discrete electrons beams linking to the reconnection region are observed to have access to spatially distinct flux tubes in < 1 s, which indicates that the reconnection region likely consists of a large number of discrete reconnection sites in a localized spatial volume. Our observations rather directly suggest a bursty reconnection scenario involving a localized reconnection region containing a distribution of many small-scale dynamically-evolving structures.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Furthermore, the multitudes of discrete electrons beams linking to the reconnection region are observed to have access to spatially distinct flux tubes in < 1 s, which indicates that the reconnection region likely consists of a large number of discrete reconnection sites in a localized spatial volume. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Our observations rather directly suggest a bursty reconnection scenario involving a localized reconnection region containing a distribution of many small-scale dynamically-evolving structures.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Conclusion ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Conclusion ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Dynamic imaging spectroscopy of type IIIdm bursts with the VLA has allowed us to map the trajectories of electron beams produced by magnetic energy release during a coronal jet event. Electrons escaped along discrete, ultra-fine magnetic tubes into the upper atmosphere, producing the observed type IIIdm bursts. Downward propagating electrons resulted in the observed HXR footpoint emission, which is closely associated with the type IIIdm bursts both temporally and spatially. Properties of the beam-conducting tubes have been deduced from the observations, including the plasma density and its variation over height, temperature, and the upper-limit of their diameter. The spatial scales in the reconnection region are likely 10s of km or less. We conclude that the magnetic energy release process is highly fragmentary and that the surrounding coronal medium is fibrous in nature. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Dynamic imaging spectroscopy of type IIIdm bursts with the VLA has allowed us to map the trajectories of electron beams produced by magnetic energy release during a coronal jet event. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Electrons escaped along discrete, ultra-fine magnetic tubes into the upper atmosphere, producing the observed type IIIdm bursts. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Downward<ins class="diffchange diffchange-inline">-</ins>propagating electrons resulted in the observed HXR footpoint emission, which is closely associated with the type IIIdm bursts both temporally and spatially. Properties of the beam-conducting tubes have been deduced from the observations, including the plasma density and its variation over height, temperature, and the upper-limit of their diameter. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The spatial scales in the reconnection region are likely 10s of km or less. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>We conclude that the magnetic energy release process is highly fragmentary and that the surrounding coronal medium is fibrous in nature. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;">[1] [http://adsabs.harvard.edu/abs/2013ApJ...763L..21C Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy]</del></div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[1] [https://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array The Expanded Very Large Array: A New Telescope for New Science]. </ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">Perley, R</del>. <del class="diffchange diffchange-inline">A</del>.<del class="diffchange diffchange-inline">, Chandler, C</del>. <del class="diffchange diffchange-inline">J</del>.<del class="diffchange diffchange-inline">, Butler, B</del>. <del class="diffchange diffchange-inline">J</del>.<del class="diffchange diffchange-inline">, & Wrobel, J</del>. <del class="diffchange diffchange-inline">M. 2011, ApJL, 739, 1</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[2] [http://adsabs</ins>.<ins class="diffchange diffchange-inline">harvard</ins>.<ins class="diffchange diffchange-inline">edu/abs/2013ApJ</ins>...<ins class="diffchange diffchange-inline">763L</ins>..<ins class="diffchange diffchange-inline">21C Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy]</ins></div></td></tr>
</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Passages_of_Electron_Beams&diff=5650&oldid=prevHhudson: starting minor edits2013-02-10T21:39:15Z<p>starting minor edits</p>
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<td colspan='2' style="background-color: white; color:black;">Revision as of 21:39, 10 February 2013</td>
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<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">{{Infobox Nugget</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|name = Nugget</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|title = Passages of Electron Beams</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|number = 194</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|first_author = Bin Chen</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|second_author = </ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|publish_date = 2013 February 11</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|next_nugget = Beams and Waves</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">|previous_nugget =[[Kappa Distributions]]</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">}}</ins></div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction== </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Introduction== </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Solar flares involve production of energetic electron beams. They carry a significant amount of magnetic energy released and therefore play a key role in flare physics. One method to probe these beams is through their radio signature: type III radio bursts. Type III radio bursts are emitted at the fundamental or harmonic of the local electron plasma frequency, f<sub>pe</sub>~9n<sub>e</sub><sup>1/2</sup> kHz, where n<sub>e</sub> is the electron number density. Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded [https://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array] ([http://adsabs.harvard.edu/abs/2011ApJ...739L...1P Perley et al. 2011]). <del class="diffchange diffchange-inline">That is, </del>an image of the radio emission can be produced at each frequency and time over a substantial frequency range. Here we report the first use of this technique to trace electron beams in the low corona through observations of type III bursts at decimeter wavelengths <del class="diffchange diffchange-inline">([http://adsabs.harvard.edu/abs/2013ApJ...763L..21C Chen et al. 2013)]</del>.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Solar flares involve <ins class="diffchange diffchange-inline">the </ins>production of energetic electron beams. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>They <ins class="diffchange diffchange-inline">may </ins>carry a significant amount of magnetic energy released and <ins class="diffchange diffchange-inline">could </ins>therefore play a key role in flare physics. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>One method to probe these beams is through their radio signature: <ins class="diffchange diffchange-inline">[http://www.lesia.obspm.fr/cesra/highlights/highlight08-1.html </ins>type III radio bursts<ins class="diffchange diffchange-inline">]</ins>. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Type III radio bursts are emitted at the fundamental or harmonic of the local electron plasma frequency, f<sub>pe</sub>~9n<sub>e</sub><sup>1/2</sup> kHz, where n<sub>e</sub> is the electron number density. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Since n<sub>e</sub> varies with height in the corona radio emission from an electron beam rapidly drifts from high to low frequencies for upward-propagating beams, and in the opposite sense for downward-propagating beams. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Type III radio bursts have been observed for decades in ''dynamic spectra'' – records of radio flux density as a function of time and frequency. </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Recently, it has become possible to perform ''dynamic imaging spectroscopy'' of these, and other, types of solar radio bursts using the recently upgraded [https://science.nrao.edu/facilities/vla Karl G. Jansky Very Large Array] ([http://adsabs.harvard.edu/abs/2011ApJ...739L...1P Perley et al. 2011]). </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">With this capability </ins>an image of the radio emission can be produced at each frequency and time<ins class="diffchange diffchange-inline">, </ins>over a substantial frequency range.</div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">In the RHESSI framework this is termed ''imaging spectroscopy.''</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Here we report <ins class="diffchange diffchange-inline">(Ref. 1) </ins>the first use of this technique to trace electron beams in the low corona through observations of type III bursts at decimeter wavelengths.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:193f1_VLA.jpg|center|thumb|600px|Karl G. Jansky Very Large Array. The VLA has been recently upgraded with state-of-art receivers and electronics, enabling dynamic imaging spectroscopic observations of the Sun.]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:193f1_VLA.jpg|center|thumb|600px|Karl G. Jansky Very Large Array. The VLA has been recently upgraded with state-of-art receivers and electronics, enabling dynamic imaging spectroscopic observations of the Sun.]]</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">Chen, B</del>.<del class="diffchange diffchange-inline">, Bastian T</del>. <del class="diffchange diffchange-inline">S</del>.<del class="diffchange diffchange-inline">, White, S</del>. <del class="diffchange diffchange-inline">M</del>.<del class="diffchange diffchange-inline">, Gary, D</del>. <del class="diffchange diffchange-inline">E</del>.<del class="diffchange diffchange-inline">, Perley, R., Rupen, M., Carlson, B. 2013, ApJL, 763, 21</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[1] [http://adsabs</ins>.<ins class="diffchange diffchange-inline">harvard</ins>.<ins class="diffchange diffchange-inline">edu/abs/2013ApJ</ins>...<ins class="diffchange diffchange-inline">763L</ins>..<ins class="diffchange diffchange-inline">21C Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy]</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div> </div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Perley, R. A., Chandler, C. J., Butler, B. J., & Wrobel, J. M. 2011, ApJL, 739, 1</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>Perley, R. A., Chandler, C. J., Butler, B. J., & Wrobel, J. M. 2011, ApJL, 739, 1</div></td></tr>
</table>Hhudson