INVESTIGATION OF ELECTRON-BEAM INTERACTION WITH A BEAM-GENERATED PLASMA (thesis)

Technical Report · Tue Feb 20 04:00:00 EST 1962

OSTI ID:4736080

Getty, W D

The beam-plasma interaction is studied and considered as a possible mechanism for the heating of plasma electrons. A strong interaction between the electron beam and a weakiy ionized gas is produced by a moderately highpermeance electron gun operating at peak pulse voltages up to 10 kv. The 3.5- mu sec, pulsed electron beam is injected into an evacuated drift region from the magnetically shielded electron gun. The beam is confined by an axial magnetic induction of several hundred gauss. As it drifts to the collector, the beam partially ionizes the background gas (argon) in the drift region. After a time delay that is required for the production of plasma by beam ionization, seif- excited uhf oscillations are observed. These oscillations are accompanied by several phenomena indicating that a strong interaction takes place. These phenomena are: scattering of the electron beam across the axial magnetic field by oscillatory, electric-field forces; generation of an intense pulse of visible light which occurs simultaneously with the beam scattering; and excitation of electrons to energies above 100 ev. Investigations of these phenomena are described and interpreted. An approximate small-signal theory of wave propagation in a cylindrical beam-plasma system is applied in the interpretation of certain properties of the plasma oscillations. Although their frequency varies rapidly with time, the oscillations start at a frequency that is determined by the magnetic induction. The conclusion reached is that, in a beamgenerated plasma system, the oscillations start at a frequency that is determined by the magnetic field and become sufficiently intense to impart a significant oscillatory energy to the plasma electrons. 58 references. (auth)

• Research Organization: Massachusetts Inst. of Tech., Cambridge. Research Lab. of Electronics
• NSA Number: NSA-17-019457
• OSTI ID: 4736080
• Report Number(s): RLE-TR-407
• Country of Publication: United States
• Language: English

Related Subjects

ARGON
BIBLIOGRAPHY
CONFINEMENT
CYLINDERS
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ELECTRODES
ELECTRON BEAMS
ELECTRONS
ENERGY RANGE
EXCITATION
FREQUENCY
GASES
HEATING
INDUCTION
INJECTION
INTERACTIONS
IONIZATION
LIGHT
MAGNETIC FIELDS
MAGNETIC MIRRORS
MEASURED VALUES
MOTION
NUMERICALS
OSCILLATIONS
PHYSICS
PLASMA
PLASMA WAVES
PULSES
SCATTERING
VACUUM