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An investigation of collisionless plasma beam interaction with a nonhomogeneous magnetic field


Lee, Peter Hoong-Yee (1973) An investigation of collisionless plasma beam interaction with a nonhomogeneous magnetic field. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/XNF6-9D90.


The interaction between a rarefied flowing plasma and an externally imposed nonhomogeneous magnetic field is studied experimentally in a collisionless plasma wind tunnel, where a collisionless plasma beam is directed through a current loop. The collisionless plasma is generated by an electron bombardment engine. Nominal values of ion flow speed, number density, electron temperature and magnetic induction of the loop are U ~10^4 m/s, N ~5 x 10^7/cc, kT_e ~0.2 eV and B ~10 Gauss, respectively. Due to lack of probe theories in the presence of nonhomogeneous magnetic fields and failure of conventional Langmuir probe methods, a new, simple method of diagnostics is developed. This method employs two probes of different geometry and obtains information on the ion density and flow speed from the ion-saturation region of the probe characteristic. Radial density profiles in the wake of the current loop mapped by the "two-probe" method indicate annular density "peaks" at certain radial positions. In order to understand this non-uniform "pinching" process, a theoretical analysis is attempted. It is found that the experimentally observed phenomenon can be qualitatively described by the collision-less two-fluid equations, but turbulent "friction" is required to improve the two-fluid model. A heuristic turbulent model is used, and evidence of turbulence in the flow field is also obtained through measurements of the fluctuating probe currents.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Aeronautics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kubota, Toshi
Thesis Committee:
  • Unknown, Unknown
Defense Date:18 May 1973
Record Number:CaltechTHESIS:08262010-104719284
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6009
Deposited By: Dan Anguka
Deposited On:26 Aug 2010 18:27
Last Modified:21 Dec 2019 04:54

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