The New updated Langmuir probe data analysis program
The program Langmuir is now updated to become more users friendly. The new program
is called
[Ne,Ni,Vp,Vf,Te,E,f]=Analyze_Langmuir(V,I,Area,Mass)
V and I are the probe current and voltage data. Area represents the probe effective area in
M
2
. Mi is the mass of the ions in atomic mass units. These should be available on the
matlab work space.
The output arguments are
1. The electron number density Ne
2. The ion number density Ni
3. The plasma potential Vp
4. The flouting potential Vf
5. The plasma electron temperature Te
6. E, and f are the electron energy distribution data.
The program fits the I-V data to the equation
4321
}]/)tanh{(exp[ aaaVaI
+
+
=
And calculated all the plasma parameters using standard procedures from the
fitted values of a
1
to a
4
After performing the fit, the software stops waiting for user approval of the
fit cross quality. If the fit is OK, just press enter. If the fit (red solid line ) is
not compatible with the experimental data ( black dots) then press control C
to stop the program and try to readjust the starting values of the fitting
parameters on line
The out puts of the program are
1. The ion saturation current Iis
2. the electron saturation current Ies
3. The electron number density /M^3
4. The ion number density /M^3
5. The mean electron temperature Te in eV
6. The plasma potential Vp in Volts
7. The plasma flouting potential in Volts
As a demonstration the experimental I-V data are included in the zip file
these are the probe voltage V, and the probe current I.
Use the following to run the program ( The I-V data are saved in I)
>>load(‘I’)
>>[Ne,Ni,Vp,Vf,Te,E,f]=Analyze_Langmuir(V,I, 6.3*10^-7,40)
The out put of the program for this test case are
