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Experimental Study of the Upper Hybrid Echo in Plasmas


Bauer, Luc-Olivier Edouard (1968) Experimental Study of the Upper Hybrid Echo in Plasmas. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6GB4-EF52.


The two-pulse stimulated radiation of dense (109/cm3 < ne ≤ 1011/cm3) nonuniform neon and argon afterglow plasma columns longitudinally immersed in a magnetic field is studied. The magnetic field is very homogeneous over the plasma volume (∆B/B ~ .01%). If the S-band microwave pulses' center frequency is such that they resonantly excite a narrow band of plasma upper hybrid oscillations close to the maximum upper hybrid frequency of the column, strong two pulse echoes are observed. This new echo process is called the upper hybrid echo. The echo spectrum, echo power and echo width were studied as a function of the pulse peak power P, pulse separation τ, relative density (ωpo/ω)2, and relative cyclotron frequency (ωc/ω). The complex but systematic variations of the echo properties as a function of the above-mentioned parameters arc found to be in qualitative agreement with those predicted by a theory of Gould and Blum based upon a simple nonuniform unidimensional cold plasma slab model. The possible effects of electron neutral and electron ion collisions not retained in the theoretical model are discussed.

The existence of a new type of cyclotron echo, different from that of Hill and Kaplan and not predicted by the Blum and Gould model is documented. It is believed to be also of a collective effect nature and can probably be described in terms of a theory retaining some hot plasma effects.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Engineering Science) ; hybrid, echo, plasmas
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Gould, Roy Walter
Thesis Committee:
  • Unknown, Unknown
Defense Date:16 May 1968
Funding AgencyGrant Number
Council of Scientific Research of SwitzerlandUNSPECIFIED
Office of Naval Research (ONR)220(50)
Record Number:CaltechTHESIS:07232014-114203833
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Appendix A. ItemElectron Tube and Microwave Laboratory Technical Report 40
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8595
Deposited By: Dan Anguka
Deposited On:23 Jul 2014 19:51
Last Modified:25 Mar 2024 21:27

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