https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&feed=atom&action=historyElectron re-acceleration and HXR emission - Revision history2024-03-29T13:17:15ZRevision history for this page on the wikiMediaWiki 1.16.0https://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5731&oldid=prevHhudson at 10:03, 23 February 20132013-02-23T10:03:54Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Marian Karlick&yacute; and Eduard Kontar</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|second_author = Marian Karlick&yacute; and Eduard Kontar</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 18</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 18</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">"</del>Burst-on-Tail<del class="diffchange diffchange-inline">"</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">[[</ins>Burst-on-Tail <ins class="diffchange diffchange-inline">(BOT)]]</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget =[[Passages of Electron Beams]]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|previous_nugget =[[Passages of Electron Beams]]</div></td></tr>
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</table>Hhudsonhttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5720&oldid=prevHeatherRatcliffe at 15:19, 18 February 20132013-02-18T15:19:33Z<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 = Heather Ratcliffe</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|first_author = Heather Ratcliffe</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>|second_author = Marian Karlick&yacute;</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>|second_author = Marian Karlick&yacute; <ins class="diffchange diffchange-inline">and Eduard Kontar</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 18</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|publish_date = 2013 February 18</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = "Burst-on-Tail"</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>|next_nugget = "Burst-on-Tail"</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5719&oldid=prevHeatherRatcliffe: /* References */2013-02-18T14:49:55Z<p><span class="autocomment">References</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://adsabs.harvard.edu/abs/1967PlPh....9..719V Oscillations and instability of a weakly turbulent plasma]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://adsabs.harvard.edu/abs/1967PlPh....9..719V Oscillations and instability of a weakly turbulent plasma]</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>[2] [http://adsabs.harvard.edu/abs/2012A%26A...539A..43K Wave-particle interactions in non-uniform plasma and the interpretation of hard X-ray spectra in solar flares</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/2012A%26A...539A..43K Wave-particle interactions in non-uniform plasma and the interpretation of hard X-ray spectra in solar flares<ins class="diffchange diffchange-inline">]</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: #eee; color:black; font-size: smaller;"><div>[3] [http://adsabs.harvard.edu/abs/2012ApJ...761..176R Density Fluctuations and the Acceleration of Electrons by Beam-generated Langmuir Waves in the Solar Corona]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[3] [http://adsabs.harvard.edu/abs/2012ApJ...761..176R Density Fluctuations and the Acceleration of Electrons by Beam-generated Langmuir Waves in the Solar Corona]</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5718&oldid=prevHeatherRatcliffe at 14:49, 18 February 20132013-02-18T14:49:30Z<p></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The primary quantity of interest is the time-averaged electron flux as a function of electron energy, which is closely related to the observed HXR emission. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The primary quantity of interest is the time-averaged electron flux as a function of electron energy, which is closely related to the observed HXR emission. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>We show this for the simulation models with and without Langmuir-wave generation (left panel), with Langmuir-wave generation and evolution due to density inhomogeneities (middle panel), and finally with wave-wave processes also included (right panel).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>We show this for the simulation models with and without Langmuir-wave generation (left panel), with Langmuir-wave generation and evolution due to density inhomogeneities (middle panel<ins class="diffchange diffchange-inline">) (see ref. [3] for details</ins>), and finally with wave-wave processes also included (right panel).</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>We see from Figure 1 that the Langmuir-wave generation alone has a very weak effect, which confirms a well-known previous result. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We see from Figure 1 that the Langmuir-wave generation alone has a very weak effect, which confirms a well-known previous result. </div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The effects of Langmuir waves on HXR emission from an electron beam were considered a long time ago, but only as an energy loss process for the beam, where they were found to have no effect on the time-averaged electron spectrum. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The effects of Langmuir waves on HXR emission from an electron beam were considered a long time ago, but only as an energy loss process for the beam, where they were found to have no effect on the time-averaged electron spectrum. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>However our simulations found significant electron acceleration, due to the redistribution of energy from below to above 20 keV. This shows that one needs far less electrons to produce the HXR spectrum as observed by, for example, RHESSI. When this HXR spectrum is analysed to deduce the electron spectrum generating the HXR emission via use of standard inversion techniques, this could be substantially overestimated.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>However our simulations found significant electron acceleration, due to the redistribution of energy from below to above 20 keV. This shows that one needs far less electrons to produce the HXR spectrum as observed by, for example, RHESSI. When this HXR spectrum is analysed to deduce the electron spectrum generating the HXR emission via use of standard inversion techniques, this could be substantially overestimated <ins class="diffchange diffchange-inline">(refs [2] and [5])</ins>.</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>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://adsabs.harvard.edu/abs/1967PlPh....9..719V Oscillations and instability of a weakly turbulent plasma]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[1] [http://adsabs.harvard.edu/abs/1967PlPh....9..719V Oscillations and instability of a weakly turbulent plasma]</div></td></tr>
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<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/<del class="diffchange diffchange-inline">2012ApJ</del>...<del class="diffchange diffchange-inline">761</del>..<del class="diffchange diffchange-inline">176R Density Fluctuations </del>and the <del class="diffchange diffchange-inline">Acceleration </del>of <del class="diffchange diffchange-inline">Electrons by Beam</del>-<del class="diffchange diffchange-inline">generated Langmuir Waves </del>in <del class="diffchange diffchange-inline">the Solar Corona]</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/<ins class="diffchange diffchange-inline">2012A%26A</ins>...<ins class="diffchange diffchange-inline">539A</ins>..<ins class="diffchange diffchange-inline">43K Wave-particle interactions in non-uniform plasma </ins>and the <ins class="diffchange diffchange-inline">interpretation </ins>of <ins class="diffchange diffchange-inline">hard X</ins>-<ins class="diffchange diffchange-inline">ray spectra </ins>in <ins class="diffchange diffchange-inline">solar flares</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>[3] [http://adsabs.harvard.edu/abs/2012A%26A...544A.148K Electron acceleration during three-dimensional relaxation of an electron beam-return current plasma system in a magnetic field]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[3<ins class="diffchange diffchange-inline">] [http://adsabs.harvard.edu/abs/2012ApJ...761..176R Density Fluctuations and the Acceleration of Electrons by Beam-generated Langmuir Waves in the Solar Corona]</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>
<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">[4</ins>] [http://adsabs.harvard.edu/abs/2012A%26A...544A.148K Electron acceleration during three-dimensional relaxation of an electron beam-return current plasma system in a magnetic field<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> </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">[5] [http://adsabs.harvard.edu/abs/2013A%26A...550A..51H Effect of turbulent density-fluctuations on wave-particle interactions and solar flare X-ray spectra</ins>]</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5717&oldid=prevHeatherRatcliffe: /* References */2013-02-18T10:37:56Z<p><span class="autocomment">References</span></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] [http://adsabs.harvard.edu/abs/<del class="diffchange diffchange-inline">1980panp</del>.<del class="diffchange diffchange-inline">book</del>.....<del class="diffchange diffchange-inline">M Plasma Astrophysics</del>]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[1] [http://adsabs.harvard.edu/abs/<ins class="diffchange diffchange-inline">1967PlPh</ins>....<ins class="diffchange diffchange-inline">9</ins>..<ins class="diffchange diffchange-inline">719V Oscillations and instability of a weakly turbulent plasma</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: #eee; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/2012ApJ...761..176R Density Fluctuations and the Acceleration of Electrons by Beam-generated Langmuir Waves in the Solar Corona]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[2] [http://adsabs.harvard.edu/abs/2012ApJ...761..176R Density Fluctuations and the Acceleration of Electrons by Beam-generated Langmuir Waves in the Solar Corona]</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>[3] [http://adsabs.harvard.edu/abs/2012A%26A...544A.148K Electron acceleration during three-dimensional relaxation of an electron beam-return current plasma system in a magnetic field]</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[3] [http://adsabs.harvard.edu/abs/2012A%26A...544A.148K Electron acceleration during three-dimensional relaxation of an electron beam-return current plasma system in a magnetic field]</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5716&oldid=prevHeatherRatcliffe: /* Quasilinear Simulations */2013-02-18T10:35:14Z<p><span class="autocomment">Quasilinear Simulations</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Quasilinear Simulations ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Quasilinear Simulations ==</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>Our model describes collisional relaxation of the energetic power-law distribution. We consider firstly a simplified model including only collisions, and then the relaxation including wave generation, and evolution.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Our model <ins class="diffchange diffchange-inline">(based on ref. [1]) </ins>describes collisional relaxation of the energetic power-law distribution. We consider firstly a simplified model including only collisions, and then the relaxation including wave generation, and evolution.</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>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:RatcliffeKontarKarlickyFig1.png|thumb|center|800px|</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[[File:RatcliffeKontarKarlickyFig1.png|thumb|center|800px|</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5715&oldid=prevHeatherRatcliffe: /* Conclusions */2013-02-18T10:33:52Z<p><span class="autocomment">Conclusions</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The effects of Langmuir waves on HXR emission from an electron beam were considered a long time ago, but only as an energy loss process for the beam, where they were found to have no effect on the time-averaged electron spectrum. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The effects of Langmuir waves on HXR emission from an electron beam were considered a long time ago, but only as an energy loss process for the beam, where they were found to have no effect on the time-averaged electron spectrum. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>However our simulations found significant electron acceleration<del class="diffchange diffchange-inline">. </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>However our simulations found significant electron acceleration, <ins class="diffchange diffchange-inline">due to </ins>the <ins class="diffchange diffchange-inline">redistribution </ins>of <ins class="diffchange diffchange-inline">energy from below </ins>to above 20 keV<ins class="diffchange diffchange-inline">. This shows that one needs far less </ins>electrons <ins class="diffchange diffchange-inline">to produce </ins>the <ins class="diffchange diffchange-inline">HXR spectrum as observed by, </ins>for <ins class="diffchange diffchange-inline">example, RHESSI</ins>. <ins class="diffchange diffchange-inline">When this </ins>HXR spectrum <ins class="diffchange diffchange-inline">is analysed </ins>to deduce the electron spectrum generating the HXR emission via use of standard inversion techniques, this <ins class="diffchange diffchange-inline">could </ins>be <ins class="diffchange diffchange-inline">substantially overestimated</ins>.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">This can solve, at least in part</del>, the <del class="diffchange diffchange-inline">electron "number problem," which says that the total number </del>of <del class="diffchange diffchange-inline">accelerated electrons is impossibly large in terms of the coronal</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">electron content.</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">By redistributing electrons </del>to <del class="diffchange diffchange-inline">energies </del>above 20 keV<del class="diffchange diffchange-inline">, the re-acceleration described in these simulations reduces the original number of </del>electrons <del class="diffchange diffchange-inline">required; this results from</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>the <del class="diffchange diffchange-inline">energy dependence of the cross-section </del>for <del class="diffchange diffchange-inline">bremsstrahlung emission</del>.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div> </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">We may still use the </del>HXR spectrum to deduce the electron spectrum generating the HXR emission<del class="diffchange diffchange-inline">, </del>via use of standard inversion techniques, <del class="diffchange diffchange-inline">but </del>this <del class="diffchange diffchange-inline">will only return the electron distribution as injected into the dense region from which bremsstrahlung originates, and this will NOT </del>be <del class="diffchange diffchange-inline">the same as the originally accelerated electron spectrum. </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">Moreover, the complex nature of the beam-wave interactions means we cannot easily, if at all, recover this original spectrum</del>.</div></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>== References ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== References ==</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5714&oldid=prevHeatherRatcliffe: /* Complementary approaches */2013-02-18T10:24:36Z<p><span class="autocomment">Complementary approaches</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Complementary approaches ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Complementary approaches ==</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>The two simulation methods presented here are very different, and each has its advantages and disadvantages. <del class="diffchange diffchange-inline">In brief:</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>The two simulation methods presented here are very different, and each has its advantages and disadvantages. </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>Quasilinear simulations <del class="diffchange diffchange-inline">as used here consider only a 1-D model, using "</del>weak turbulence<del class="diffchange diffchange-inline">" </del>theory.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>Quasilinear simulations <ins class="diffchange diffchange-inline">use </ins>weak turbulence theory. Computationally such simulations are fast, and the beam-plasma interaction is well treated by such a model. PIC simulations are computationally demanding <ins class="diffchange diffchange-inline">and limited to short time and spatial scales</ins>, and thus require such approximations as a small electron-proton mass ratio, and a small number of particles. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">The magnetic field is ignored, except as a guiding force for the electron beam. </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>However, the effects of magnetic field can be included, and the treatment is fully 3-D and self-consistent. Thus the two methods offer very good independent confirmation, and together give a strong argument for such an acceleration effect occurring.</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Computationally such simulations are <del class="diffchange diffchange-inline">simple and </del>fast, and the beam-plasma interaction is well treated by such a model. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">Moreover, we can argue in favour of an almost 1-D electron dynamics.</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div> </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>PIC simulations are computationally demanding, and thus require such approximations as a small electron-proton mass ratio, and a small number of particles. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>However, the effects of magnetic field can be included, and the treatment is fully 3-D and self-consistent. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div> </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>Thus the two methods offer very good independent confirmation, and together give a strong argument for such an acceleration effect occurring.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div></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>== Conclusions ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== Conclusions ==</div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5713&oldid=prevHeatherRatcliffe: /* PIC simulations */2013-02-18T10:22:44Z<p><span class="autocomment">PIC simulations</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>It is also possible to use a 3D</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>It is also possible to use a 3D</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[http://en.wikipedia.org/wiki/Particle-in-cell "particle-in-cell"] (PIC) simulation <del class="diffchange diffchange-inline">used </del>to consider</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[http://en.wikipedia.org/wiki/Particle-in-cell "particle-in-cell"] (PIC) simulation to consider</div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">a similar </del>problem<del class="diffchange diffchange-inline">, that </del>of a monoenergetic beam injected into a plasma, with the effects of wave-wave interactions included. </div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">the </ins>problem of a monoenergetic beam injected into a plasma, with the effects of wave-wave interactions included. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In these PIC simulations (ref [3]) the proton-electron mass ratio was taken to be 16 for computational reasons, but that is sufficient for these simulations. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>In these PIC simulations (ref [3]) the proton-electron mass ratio was taken to be 16 for computational reasons, but that is sufficient for these simulations. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The initial electron beam was homogeneous throughout the numerical box of the simulation, and an appropriate return current introduced to</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The initial electron beam was homogeneous throughout the numerical box of the simulation, and an appropriate return current introduced to</div></td></tr>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://sprg.ssl.berkeley.edu/~hhudson/plasma/webpage/plasma.html plasma frequency], equal to 0.0, 0.1, 0.5, 0.7,</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>[http://sprg.ssl.berkeley.edu/~hhudson/plasma/webpage/plasma.html plasma frequency], equal to 0.0, 0.1, 0.5, 0.7,</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>1.0, and 1.3, respectively (models A-F). </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>1.0, and 1.3, respectively (models A-F). </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>As can be <del class="diffchange diffchange-inline">see </del>here, there are electrons</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>As can be <ins class="diffchange diffchange-inline">seen </ins>here, there are electrons</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>accelerated above their initial energy, and the number of these increases with the magnetic field strength. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>accelerated above their initial energy, and the number of these increases with the magnetic field strength. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is due to the </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>This is due to the </div></td></tr>
</table>HeatherRatcliffehttps://sprg.ssl.berkeley.edu/~tohban/wiki/index.php?title=Electron_re-acceleration_and_HXR_emission&diff=5712&oldid=prevHeatherRatcliffe: /* Quasilinear Simulations */2013-02-18T10:21:31Z<p><span class="autocomment">Quasilinear Simulations</span></p>
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<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The primary quantity of interest is the time-averaged electron flux as a function of electron energy, which is closely related to the observed HXR emission. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>The primary quantity of interest is the time-averaged electron flux as a function of electron energy, which is closely related to the observed HXR emission. </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 Figure 1 we </del>show this for the simulation models with and without Langmuir-wave generation (left panel), with Langmuir-wave generation and evolution due to density inhomogeneities (middle panel), and finally with wave-wave processes also included (right panel).</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">We </ins>show this for the simulation models with and without Langmuir-wave generation (left panel), with Langmuir-wave generation and evolution due to density inhomogeneities (middle panel), and finally with wave-wave processes also included (right panel).</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>We see from Figure 1 that the Langmuir-wave generation alone has a very weak effect, which confirms a well-known previous result. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>We see from Figure 1 that the Langmuir-wave generation alone has a very weak effect, which confirms a well-known previous result. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>However, the time evolution of the Langmuir waves can produce significant changes in the HXR emission. </div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>However, the time evolution of the Langmuir waves can produce significant changes in the HXR emission. </div></td></tr>
<tr><td class='diff-marker'>-</td><td style="background: #ffa; color:black; font-size: smaller;"><div>For the model parameters chosen, this occurs primarily between 20 and 200 keV, and within this range we can expect an increase in HXR emission of <del class="diffchange diffchange-inline">a few times, or perhaps </del>an order of magnitude.</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>For the model parameters chosen, this occurs primarily between 20 and 200 keV, and within this range we can expect an increase in HXR emission of an order of magnitude <ins class="diffchange diffchange-inline">(Figure 1)</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: #eee; color:black; font-size: smaller;"><div>== PIC simulations ==</div></td><td class='diff-marker'> </td><td style="background: #eee; color:black; font-size: smaller;"><div>== PIC simulations ==</div></td></tr>
</table>HeatherRatcliffe