Microwave parametric amplification in gas plasmas and electron beams

Technical Report · Sun Dec 31 04:00:00 EST 1972

OSTI ID:4934900

Naoulo, M

Thesis. A theory is developed for the parametric amplification of traveling waves which takes into account the existence of a finite-valued confining magnetic field as well as the radial and azimuthal motion of the electrons. Three cases are dealt with: an electron beam, a plasma column, and a mixed beam--plasma system. The beam--plasma system is a cylindrical column of finite radius maintained under vacuum. The ionized gas is modulated by the pump. The signal which is subsequently injected is amplified by coupling it with the pump, this being possible as a result of the nonlinear properties of the system. Linear analysis of the dispersion yields the propagation parameters of the separately injected waves. The simultaneous excitation modifies these parameters. An analysis of the propagation of the waves, taking into account second-order nonlinear terms, enables the nonlinear component of the current density to be obtained. An experimental device was constructed in which the waves are injected in a beam-plasma column. The power level of the waves was measured along the entire length of this column in order to determine the parametric gain. The column was obtained by plasma diffusion from a hollow cathode discharge. The variations in the paramagnetic gain are presented as a function of the powers and frequencies of the waves as well as a function of the beam--plasma medium. The following cases were analyzed: plasma only, beam only, pump frequency of less than the signal frequency, generation of waves, and the gain for waves with a frequency equal to the sum of the plasma and beam frequencies. (FR)

• Research Organization: Paris-11 Univ., 91 - Orsay (France)
• Sponsoring Organization: Sponsor not identified
• NSA Number: NSA-29-009142
• OSTI ID: 4934900
• Report Number(s): FRNC-TH--400
• Country of Publication: France
• Language: French

Related Subjects

BEAM-PLASMA SYSTEMS
CONFINEMENT
COUPLING
ELECTRON BEAMS
GAIN
GHZ RANGE
MAGNETIC FIELDS
N70300* --Physics--Controlled Thermonuclear Research-- Kinetics (General)
NONLINEAR PROBLEMS
PARAMETRIC AMPLIFIERS
PLASMA
PLASMA INSTABILITY
TRAVELLING WAVES
WAVE PROPAGATION