Ion sensor for 1e20 ions/m3 density

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Javier Lopez
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What kind of ion sensor can I use in the range 1e19to 1e22 ions/m3?
(corresponds to 0.1 to 5 pascals if non ionized)
Does it exist any sensor based in the charge capacity?
 
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You can measure up to 4e19 densities by detecting plasma cutoff (resonance) frequency with network analyser; for higher densities i afraid you need conduction-based measurement setup - basically cold cathode ionization gauge, but biased well below breakdown to measure ions only
 
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thank you, I will look for that and write about here
Does the resonance is related to ion gyroradius in a magnetic field? How to avoid electron running in opposite direction?
There is any ion density probe based on space charge?
 
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Javier Lopez said:
thank you, I will look for that and write about here
Does the resonance is related to ion gyroradius in a magnetic field? How to avoid electron running in opposite direction?
There is any ion density probe based on space charge?
No, resonance i mean is Langmuir waves (do not mistake with completely different Langmuir probe method)
 
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Very good! that works also with ions, not only electrons!.
I suppose this is the formula (where e & m are charge in coulombs and ion mass in Kg):
$$n_0=\frac{w^2*\epsilon_0*m}{e^2}$$
Do you use V2 to send and V3 langmuir probe to receive?
 
Last edited:
Javier Lopez said:
Very good! that works also with ions, not only electrons!.
I suppose this is the formula (where e & m are charge in coulombs and ion mass in Kg):
$$n_0=\frac{w^2*\epsilon_0*m}{e^2}$$
Do you use V2 to send and V3 langmuir probe to receive?
Yes, the equation above is for Langmuir wave frequency conversion to concentration.
Regarding second question, i do not completely understand but likely it related to triple Langmuir probe. It is a specialized setup and i did not use it before.
 
There are some Langmuir tripole probe with 4 electrodes, what is the function of the 4th pole?
200px-Multipin.jpg
 

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Looks like scanning probe - a switchable electrode array. Roles of each electrode is user-defined.