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Title: A segmented multi-loop antenna for selective excitation of azimuthal mode number in a helicon plasma source

A flat type, segmented multi-loop antenna was developed in the Tokai Helicon Device, built for producing high-density helicon plasma, with a diameter of 20 cm and an axial length of 100 cm. This antenna, composed of azimuthally splitting segments located on four different radial positions, i.e., r = 2.8, 4.8, 6.8, and 8.8 cm, can excite the azimuthal mode number m of 0, ±1, and ±2 by a proper choice of antenna feeder parts just on the rear side of the antenna. Power dependencies of the electron density n{sub e} were investigated with a radio frequency (rf) power less than 3 kW (excitation frequency ranged from 8 to 20 MHz) by the use of various types of antenna segments, and n{sub e} up to ∼5 × 10{sup 12} cm{sup −3} was obtained after the density jump from inductively coupled plasma to helicon discharges. Radial density profiles of m = 0 and ±1 modes with low and high rf powers were measured. For the cases of these modes after the density jump, the excited mode structures derived from the magnetic probe measurements were consistent with those expected from theory on helicon waves excited in the plasma.
Authors:
 [1] ;  [2] ;  [3]
  1. Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)
  2. Research Institute of Science and Technology, Tokai University, 4-1-1, Kita-kaname, Hiratsuka, Kanagawa 259-1292 (Japan)
  3. National Institute of Advanced Industrial Science and Technology (AIST), 807-1, Shuku-machi, Tosu, Saga 841-0052 Japan (Japan)
Publication Date:
OSTI Identifier:
22314276
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANTENNAS; ELECTRON DENSITY; EXCITATION; HELICON WAVES; LENGTH; MAGNETIC PROBES; MHZ RANGE; PLASMA DENSITY; RADIOWAVE RADIATION