Published March 1969 | Version v1
Book

Experimental Strong Turbulent Heating

  • 1. Oak Ridge National Laboratory, Oak Ridge, TN (United States)

Description

Experiments at ORNL are exploring the strong turbulent interaction between a steady-state, magnetically collimated electron beam and its self-generated plasma. The technology to maximize ion heating is being developed in Burnout V, a simple mirror device with magnetic fields of 50-25-50 kG, and with an axial electron beam (6 A at 10 kV) which gives a beam power density in the plasma exceeding one kW cm-3. Necessary, but not sufficient, evidence for a true thermonuclear temperature is the observed 103 s-1 cm-3 plasma source of 3-MeV protons identifying D-D reactions. Spectral measurements of recombination radiation reveal a line width corresponding to an ion energy of 0.5 keV. Analysis of charge-exchanged neutral atoms reveals the energy spectrum in more detail with a maximum between 100-500 eV and as much as 10 percent near one keV. A flux of 3 x 1014 cm-2 s-1 of 100 keV deuterons escapes the midplane perimeter. Calorimetric probes measure a plasma heating effect equivalent to 0.5 keV ion bombardment at 2.5 x 1012 cm-3 . The rate of decrease of spectral radiation toward the plasma centre establishes an electron density of at least 2,5 x 1012 cm3 . The confinement time, 2 x 104 s estimated from density and energy balance, agrees well with the measured spectral light decay time and is equivalent to hundreds of ion transits through the plasma. Ion heating has been observed to increase strongly with increasing magnetic field strength, suggesting a direction for future development. In previous experiments electrons were heated to temperatures exceeding 100 keV with densities greater than 1011 cm-3. To study these oscillations, special impedance-matched probes now have been used to measure plasma electron oscillation frequencies up to 4 kMc, coherence times, and electric field values with the aid of travelling-wave tube oscilloscopes. Simple methods related to correlation techniques have been used to estimate the auto- and cross-correlations on the signals observed on two electrostatic probes, with the aid of sampling oscilloscopes used as high-speed gates. These techniques allow us to observe ''average'' frequencies up to 2 kMc and ''average'' wavelengths which are observed to be a few cm. All these new techniques aid us in determining the dispersion relation and other important quantities for the plasma-electron oscillations, and help us in determining the direction for future progress. (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. 693-708
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)

Optional Information

Lead record
61a4m-c8n42
Notes
9 refs., 13 figs. Imprint:In two volumes
Secondary number(s)
IAEA-CN--24/L-2