Published March 1969 | Version v1
Book

Excitation of Oscillations Between the Ion Cyclotron and Electron Plasma Frequency in an Ion-Beam Generated Plasma

Creators

  • 1. Institut für Plasmaphysik, Garching, Munich (Germany)

Description

A helium ion beam propagating near the axis of a grounded metal cylinder with grounded grids at its ends penetrates neutral helium gas and generates a beam-plasma column. The beam-plasma is radially confined by a homogeneous magnetic field aligned parallel to the axis of the metal cylinder. The length of the plasma column, i.e. the distance between the two grids, is variable up to 100 cm and the diameter of the metal cylinder is 20 cm, whereas the beam diameter is about 2 cm. With neutral gas pressures in the range of about 104 Torr, beam energies of about 10 keV, beam currents of a few milliamperes and magnetic fields of some thousand gauss, oscillations with radial field amplitudes up to a few volts per centimeter in the megacycle range together with their lower ''harmonics'' are picked up by probes. The oscillation spectrum is more or less continuous, having apparent peaks at the ''harmonic'' frequencies. Oscillation amplitude measurements carried out along the plasma column with a movable probe, giving something like a standing wave envelope, and interference measurements between a fixed and a movable probe indicate phase velocities greater than the beam velocity. According to the dispersion diagram of a cold cylindrical beam-plasma these oscillations belong to a wave propagating between the fast cyclotron wave and the ω-k-plane, i.e. to the electron plasma wave. Since this wave is stable in an infinitely long system, it is assumed that it be coupled to the unstable space charge wave by the axial boundary conditions of the finite beam plasma. This yields the desired instability and also a quantitative representation of the observed frequency spectrum. (author)

Additional details

Publishing Information

Publisher
IAEA
Imprint Place
Vienna (International Atomic Energy Agency (IAEA))
Imprint Title
Plasma Physics and Controlled Nuclear Fusion Research. Proceedings of the Third International Conference on Plasma Physics and Controlled Nuclear Fusion Research. Vol. II
Imprint Pagination
852 p.
Journal Series
Proceedings Series
Journal Page Range
p. 785-792
ISSN
0074-1884

Conference

Title
3. international conference on plasma physics and controlled nuclear fusion research
Dates
1-7 Aug 1968
Place
Novosibirsk, USSR (Russian Federation)

INIS

Country of Publication
International Atomic Energy Agency (IAEA)
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
44064152
Subject category
S70: PLASMA PHYSICS AND FUSION TECHNOLOGY;
Resource subtype / Literary indicator
Conference
Quality check status
Yes
Descriptors DEI
AMPLITUDES; BEAM CURRENTS; BOUNDARY CONDITIONS; CYCLOTRONS; CYLINDERS; DISPERSION RELATIONS; ELECTRON PLASMA WAVES; ELECTRONS; EXCITATION; HARMONICS; HELIUM IONS; INTERFERENCE; ION BEAMS; KEV RANGE; LANGMUIR FREQUENCY; MAGNETIC FIELDS; PHASE VELOCITY; PLASMA INSTABILITY; SPACE CHARGE; STANDING WAVES;
Descriptors DEC
ACCELERATORS; BEAMS; CHARGED PARTICLES; CURRENTS; CYCLIC ACCELERATORS; ELEMENTARY PARTICLES; ENERGY RANGE; ENERGY-LEVEL TRANSITIONS; FERMIONS; INSTABILITY; IONS; LEPTONS; OSCILLATIONS; PLASMA WAVES; VELOCITY;

Optional Information

Lead record
61a4m-c8n42
Notes
6 refs., 6 figs. Imprint:In two volumes
Secondary number(s)
IAEA-CN--24/L-9