这是一个很长的脚本，但是我觉得呈现所有信息对于理解正在发生的事情很重要。在给定速度分量输入的情况下，当我尝试计算“ ev”是电子在eV中的能量，而“ cs”是基于eV的跨截面面积函数时，会出现主要问题。我这样做是为了使速度分量在每个时间步长随机变化，但是，无论系统接受什么速度，“ ev”和“ cs”矩阵都保持相同的值。我不知道为什么，因为当我在没有for循环的情况下测试每个函数时，它们都能正确运行并生成不同的值。
主脚本中引用的“ ev”函数：
function [ev] = evfun(vx,vy,vz)
m_e = 9.11E-31; %Mass of electron
jtoev = 6.24E+18; %Joules to eV conversion
ev = jtoev*(0.5*(m_e)*(vx.^2+vy.^2+vz.^2));
%ev = log(nonfitev);
end
在主脚本中引用的“ cs”函数”
function cs = crosecarc(ev)
nonfitcs = 34*exp(-((ev-500)/350)^2); %In units of 1E-16 cm^2
cs = nonfitcs*(1E-4); %Converts to 10^-16 m^2
end
主脚本：
filename = 'evtestsheet'; %Specify file name to print to
evmatsheet = 1; %Specify sheet in Excel File
evmatxlRange = 'G3'; %Specify evmat matrix start cell in Excel File
inputvelsheet = 1; %Specify sheet in Excel File
inputvelxlRange = 'D3'; %Specify inputvel matrix start cell in Excel File
inputpossheet = 1; %Specify sheet in Excel File
inputposxlRange = 'A3'; %Specify inputpos matrix start cell in Excel File
%Defining Space and Particle Density based on Pressure PV = nkT
mTorr = 500; %Define pressure in mTorr (From metter reading)
P = (mTorr/1000)*133.322; %mTorr to Pascal conversion to define pressure
k = 1.38E-23; %Boltzman Constant
T = 290; %Temperature in Kelvin. Converted from C and @ room temp
N = 1; %Total number of particles
ChamTotalV = 1;
%Particle sweep volume is defined later because it depends on electron energy
tstep = 0.05E-8; %Defining time step
%modstep = 2*tstep; %Used when calculating volume swept since the DOE solver splits itself up into 3 times within each time step
tfin = 1.1E-8; %Defining final time
intspan = [0:tstep:tfin]; %Total time span
intspancol = intspan(:); %For Excel plotting purposes
[introw,intcol] = size(intspan);
%This section is just for generating matrices that will be populated later
tindex = [0:1:intcol-2];
tindexcol = tindex(:); %Purely for Excel plotting purposes
[tinrow,tincol] = size(tindex);
PCPmat = zeros(tincol,1);
choicemat = zeros(tincol,1);
colnewv = zeros(intcol,3);
Vsweepmat = zeros(intcol,1);
vmagmat = zeros(intcol,1);
evmat = zeros(intcol,1);
crossareamat = zeros(intcol,1);
inputpos = zeros(intcol,3);
inputvel = zeros(intcol,3);
%Test Initial Conditions
spart = [0.1 0.1 0.];
vpart = [-1.0585E+7 -1.0585E+7 0.5585E+7];
%for p = 1:1:size(s0parts) %particle count
for t = 0:1:intcol-2; %complete time interval and time step
[trow,tcol] = size(t);
%spart = s0parts(p:p,1:3);
%vpart = v0parts(p:p,1:3);
%Defining relative position and velocity
x = spart(1);
y = spart(2);
z = spart(3);
vx = vpart(1);
vy = vpart(2);
vz = vpart(3);
inputvel(t+1,1:3) = [vx vy vz];
inputpos(t+1,1:3) = [x y z];
r = sqrt(x.^2 + y.^2 + z.^2);
vmag = sqrt(vx.^2 + vy.^2 + vz.^2);
ev = evfun(vx,vy,vz); %Plugs in velocity components of electron into the "evfun" function defined in seperate file to find energy in eV
cs = crosecarc(ev); %Plugs in energy of electron into the "crosecarc" function defined in seperate file to find crossectional area
crossarea = cs*4;
Vsweep = crossarea*vmag*tstep; %Volume of space swept out by particle Vsweep = (area cross section)*(vmag)*(time step)
%nden = N/ChamTotalV; %Number of particles per unit volume
nden = 1/Vsweep; %Test line to force collision at every time step
PCP = nden*Vsweep; %Probability of collision
choice = rand(1); %Generate random number "choice" between 0 and 1
%Populate the previously generated matrices with current values
evmat(t+1,1) = ev;
crossareamat(t+1,1) = crossarea;
vmagmat(t+1,1) = vmag;
Vsweepmat(t+1,1) = Vsweep;
PCPmat(t+1,1) = PCP;
choicemat(t+1,1) = choice;
if choice <= PCP %If the choice by system is accepted within probability amplitude, then collision occurs
%Assign new, velocity components based on energy prior to collision
vxrand = 2*rand()-1; %Random # generation for component x between -1 and 1
vyrand = 2*rand()-1; %Random # generation for component y between -1 and 1
vzrand = 2*rand()-1; %Random # generation for component z between -1 and 1
vmagrand = sqrt(vxrand.^2 + vyrand.^2 + vzrand.^2); %Normalize the randomly generated components
vx = (vxrand/vmagrand)*vmag; %Multiply normalized, random x component by original velocity magnitude
vy = (vyrand/vmagrand)*vmag; %Multiply normalized, random y component by original velocity magnitude
vz = (vzrand/vmagrand)*vmag; %Multiply normalized, random z component by original velocity magnitude
else
newv = [0 0 0];
end
%Redfine the velocity and position components to reference on next if-loop run
spart(1) = x;
spart(2) = y;
spart(3) = z;
vpart(1) = vx;
vpart(2) = vy;
vpart(3) = vz;
ev = [];
%Clears ev matrix
end
xlswrite(filename,inputvel,inputvelsheet,inputvelxlRange)
xlswrite(filename,inputpos,inputpossheet,inputposxlRange)
xlswrite(filename,evmat,evmatsheet,evmatxlRange)