Electron Bernstein wave electron temperature profile diagnostic

Taylor, G. ; Efthimion, P. ; Jones, B. ; Munsat, T. ; Spaleta, J. ; Hosea, J. ; Kaita, R. ; Majeski, R. ; Menard, J.

Princeton University. Plasma Physics Laboratory.

关键词: Cdx-U Spheromak;    Plasma Diagnostics;    70 Plasma Physics And Fusion Technology;    Bernstein Mode;    Electron Plasma Waves;   

DOI  :  10.2172/758660
RP-ID  :  PPPL-3476
RP-ID  :  AC02-76CH03073
RP-ID  :  758660

美国|英语

来源: UNT Digital Library

【 摘 要 】

Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. where the plasma frequency is much greater than the electron cyclotron frequency, as in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition. Electron Bernstein waves (EBWs) are electrostatic waves that can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large perpendicular wavenumber. This paper reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub o} {approximately} 2 kG, {approximately}10{sup 13} cm{sup {minus}3} and T{sub e} {approx} to 10 -- 200 eV. Results are presented for electromagnetic measurements of EBW emission, mode-converted near the plasma edge. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode converted EBW radiation temperature was found to be less than or equal to T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe and a 140 GHz interferometer were employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance, where the mode conversion of the EBWs is expected to occur. Initial results suggest EBW emission and EBW heating are viable concepts for overdense plasmas.