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Directed Electron Velocity Distributions in Rare Gas Discharges Using Guard Ring Probes


Bond, Robert Harold (1965) Directed Electron Velocity Distributions in Rare Gas Discharges Using Guard Ring Probes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/VZM2-A856.


An experimental technique for determining detailed properties of anisotropic electron velocity distributions is described. For a planar Langmuir probe it is shown that g(vz) = - [(mJp)/(e2∂Vp)] where vz = √[2(e/m)Vp] and g(vz) gives the density of electrons with velocities normal to the probe in the range vz to vz + dvz. This expression is valid for any distribution function making it possible to study anisotropies merely by changing the orientation of the probe. If the distribution function is isotropic the above expres- sion is valid for cylindrical and small spherical probes as well.

This technique is applied to the measurement of the directional properties of electron velocity distributions in the positive column of neon and helium hot cathode discharges. The necessary planar probe consists of a 0.01 inch diameter circular probe surrounded by a 0.090 inch square guard-ring. The measured distributions were Druyvesteyn in form except that all electrons were shifted in energy (in the direction of the external field) by an amount proportional to Eλ(vz). Here E is the magnitude of the external electric field and λ(vz) the electron mean free path as a function of vz. The experimental conditions are shown to be identical with those necessary in the derivation of the Druyvesteyn distribution.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Electrical Engineering and Physics)
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Electrical Engineering
Minor Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Langmuir, Robert V. (advisor)
  • Gould, Roy Walter (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:14 May 1965
Funding AgencyGrant Number
Office of Naval Research (ONR)220(50)
Hughes Aircraft CompanyUNSPECIFIED
Record Number:CaltechETD:etd-09262002-144942
Persistent URL:
Related URLs:
URLURL TypeDescription ItemElectron Tube and Microwave Laboratory Technical Report 25
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3775
Deposited By: Imported from ETD-db
Deposited On:27 Sep 2002
Last Modified:30 Jan 2024 00:45

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