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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-4834
DTSTART:20180423T170500Z
DURATION:PT1H0M0S
DTSTAMP:20260419T102652Z
LAST-MODIFIED:20180419T163018Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Helicons\, Whistlers\, Lower Hybrid Waves: Physics of Wave Pro
 pagation and Absorption for Current Drive Via Landau Damping\, Plasma 
 Physics (Physics/ECE/NE 922) Seminar\, Robert I. Pinsker\, General Ato
 mics
DESCRIPTION:In this seminar\, I present the application of plasma wave
 s in the lower hybrid range of frequencies (LHRF) for current drive in
  tokamaks. Wave damping mechanisms in a nearly collisionless hot magne
 tized plasma are briefly described\, and the connections between the p
 roperties of the damping mechanisms and the optimal choices of wave pr
 operties (mode\, frequency\, wavelength) are explored. The two wave mo
 des available for current drive in the LHRF are described and compared
 . The terms applied to these waves in different applications of plasma
  physics are elucidated. The character of the ray paths of these waves
  in the LHRF is illustrated in slab and toroidal geometries. Applicati
 ons of these ideas to experiments in the DIII-D tokamak are discussed.
  Experiments are already underway using the 'helicon' wave (fast wave 
 in the lower hybrid range of frequencies) at 0.5 GHz. The antenna/plas
 ma coupling in the linear (very low power) regime of a 12-element 'com
 b-line' traveling wave antenna has been measured in tokamak discharges
 \; a high-power system at ~1 MW power with a 30-element comb-line is i
 n preparation. Experiments at a similar power level using the lower hy
 brid (slow) wave at 4.6 GHz are planned\; the key feature of these exp
 eriments will be the location of the 'grill' wave-launcher on the high
 -field (small major radius) side of the torus to obtain much better wa
 ve accessibility to the core than would be possible using the conventi
 onal placement of the launcher on the low-field (large major radius) s
 ide at the outboard mid-plane.
URL:https://www.physics.wisc.edu/events/?id=4834
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