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Diffusion FENNECS: Finite Element Non-Neutral Electron Cloud Simulator (geom_testmumps) Browse

fennecs/matlab/timescales.m
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timescales.m
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Pn=1e-8;%mbar
kb=1.38064852e-23;
T=300;
estimneutraldensity=Pn*100/(kb*T);
nb=estimneutraldensity;
qe=1.60217662E-19;
me=9.109383E-31;
eps_0=8.85418781762e-12;
vlight=299792458;
Ee=[10]; %eV
gridsize1=ceil(sqrt(length(Ee)));
gridsize2=ceil(length(Ee)/gridsize1);
fighandle=figure;
for i=1:length(Ee)
subplot(gridsize2,gridsize1,i)
ve=sqrt(Ee(i)*qe/me); %m/s
gamma=1/(1-ve^2/vlight^2);
ne=5*logspace(13,17,3000);
B0=0.21;
sigion=sigmabeb(15.58,54.91,2,1,Ee(i));
sigion=sigmabeb(41.72,71.13,2,1,Ee(i))+sigion;
sigion=sigmabeb(21,63.18,2,1,Ee(i))+sigion;
sigion=sigmabeb(17.07,44.30,4,1,Ee(i))+sigion;
Coulomblog=log(sqrt(eps_0*Ee(i)/qe*ne)/qe^2*2*pi*eps_0*me*ve^2);
ne_0=1;
tauion=1./(nb*sigion*ve);
tauloss=tauion*log(ne/ne_0);
taucycl=2*pi*me*gamma/qe/B0;
taupe=2*pi*sqrt(eps_0*me*gamma/qe^2./ne);
tauthermal=1./(ve*ne*qe^4.*Coulomblog./(gamma^2*me^2*ve^4*2*pi*eps_0^2));
ldw=1.5;
loglog(ne,tauion*ones(size(ne)),'displayname','\tau_{ion}','linewidth',ldw)
hold on
loglog(ne,tauloss,'displayname','t_{accum}','linewidth',ldw)
loglog(ne,tauthermal,'displayname','\tau_{thermal}','linewidth',ldw)
loglog(ne,taucycl*ones(size(ne)),'displayname','\tau_{ce}','linewidth',ldw)
loglog(ne,taupe,'displayname','\tau_{pe}','linewidth',ldw)
legend('location','eastoutside')
%title(sprintf('E_e=%#.3g eV',Te(i)))
xlabel('n_e [m^{-3}]')
ylabel('\tau [s]')
grid on
end
sgtitle(sprintf('E_e=%3.2g [eV], P_n=%3.2g [mbar]',Ee(1),Pn))
%% Saves the given figure as a pdf and a .fig
fighandle.PaperUnits='centimeters';
papsize=[12 10];
fighandle.PaperSize=papsize;
name=sprintf('timescaleE%2.0eP%2.0embar',Ee(1),Pn);
print(fighandle,name,'-dpdf','-fillpage')
savefig(fighandle,name)
% Te=500;
% ve=sqrt(Te*qe/me); %m/s
% gamma=1/(1-ve^2/vlight^2);
% time=logspace(-5,1,500);
% dens=exp(time/tauion);
% Coulomblog=log(sqrt(eps_0*Te/qe*dens)/qe^2*2*pi*eps_0*me*ve^2);
% tauthermal=1./(ve*dens*qe^4.*Coulomblog./(gamma^2*me^2*ve^4*2*pi*eps_0^2));
% figure
% yyaxis left
% loglog(time,dens)
% yyaxis right
% loglog(time,tauthermal)
% Sigma BEB see (https://physics.nist.gov/PhysRefData/Ionization/intro.html)
% B binding energy
% U average kinetic energy
% N electron occupation number
% Q dipole constant
% T incident energy
function sig=sigmabeb(B,U,N,Q,T)
t=T/B; %incident energy
u=U/B; % Average kinetic energy
% B:
a0=0.52918e-10;
R=13.6057;
S=4*pi*a0^2*N*(R/B)^2;
n=1;
sig=S/(t+(u+1)/n)*(Q*log(t)*0.5*(1-t^-2)+(2-Q)*(1-t^-1-log(t)/(t+1)));
end
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