;+ ;FUNCTION: swe_n_3d(dat,EBINS=ebins,ABINS=abins,DBINS=dbins) ;INPUT: ; dat: structure, 2d data structure filled mvn_swe_get3d ;KEYWORDS ; EBINS: bytarr(na), optional, energy bins array for integration ; 0,1=exclude,include, na = dat.nenergy ; ABINS: bytarr(16), optional, anode bins array for integration ; 0,1=exclude,include ; DBINS: bytarr(6), optional, deflector bins array for integration ; 0,1=exclude,include ; ; OBINS: bytarr(96), optional, solid angle bins for integration ; 0,1=exclude,include ;PURPOSE: ; Returns the density, n, 1/cm^3 ; ;CREATED BY: ; J.McFadden 95-7-27 ;LAST MODIFICATION: ; 96-7-6 J.McFadden added more keywords ; 14-7-6 D.Mitchell redefined keywords, ; added correction for spacecraft potential ;- function swe_n_3d, dat2, EBINS=ebins, ABINS=abins, DBINS=dbins density = 0. if dat2.valid eq 0 then begin dprint, 'Invalid Data' return, density endif dat = conv_units(dat2,"eflux") ; Use Energy Flux (eV/cm2-sec-ster-eV) data = dat.data na = dat.nenergy nb = dat.nbins pot = dat.sc_pot ; Spacecraft potential (V) ebins2 = replicate(1B,na) if keyword_set(ebins) then ebins2 = ebins abins2 = replicate(1B,16) if keyword_set(abins) then abins2 = abins dbins2 = replicate(1B,6) if keyword_set(dbins) then dbins2 = dbins obins2 = reform(abins2 # dbins2, nb) bins2 = ebins2 # obins2 ; Calculate energy steps for integral energy = dat.energy[*,0] denergy = energy denergy[0] = abs(energy[1] - energy[0]) for i=1,(na-2) do denergy[i] = abs(energy[i+1] - energy[i-1])/2. denergy[na-1] = abs(energy[na-1] - energy[na-2]) ; Calculate phi steps for integral phi = dat.phi*!dtor dphi = phi i0 = 16*indgen(6) dphi[*,i0] = abs(phi[*,i0+1] - phi[*,i0]) for i=1,14 do dphi[*,i0+i] = abs(phi[*,i0+i+1] - phi[*,i0+i-1])/2. dphi[*,i0+15] = abs(phi[*,i0+15] - phi[*,i0+14]) ; Calculate theta steps for integral the = dat.theta*!dtor dthe = the i0 = indgen(16) dthe[*,i0] = abs(the[*,i0+16] - the[*,i0]) for i=1,4 do dthe[*,i0 + i*16] = abs(the[*,i0 + (i+1)*16] - the[*,i0 + (i-1)*16])/2. dthe[*,i0 + 5*16] = abs(the[*,i0 + 5*16] - the[*,i0 + 4*16]) ; Calculate solid angles for integral ; Theta is latitude, from -90 to +90 degrees. domega = 2.*dphi*cos(the)*sin(dthe/2.) sumdata = total(data*domega*bins2,2) fovcorr = total(domega*(replicate(1.,na)#obins2),2)/(4.*!pi) prat = (pot/energy) < 1. ; Calculate the moment [cm-3] mass = 5.6856297d-06 ; electron mass [eV/(km/s)^2] Const = 1d-5 * sqrt(mass/2D) density = Const*total(denergy*sqrt(1. - prat)*(energy^(-1.5))*sumdata/fovcorr) return, density end