Absorption around the electron cyclotron frequency in a thermal plasma of finite density

Abstract

Cyclotron absorption around the electron cyclotron frequency in a weakly relativistic plasma of finite density in thermal equilibrium is considered for both perpendicular and quasi‐perpendicular propagation. A comprehensive analysis which includes thermal effects together with finite density corrections is given and the resulting scaling of the absorption of the extraordinary and the ordinary modes is examined. The line profiles are discussed and the optical thicknesses of a typical tokamak plasma are evaluated.

Using perpendicular electron cyclotron emission to diagnose the thermal-barrier electrons in a tandem mirror

“…for frequencies around the cyclotron harmonics, or [5] <\ (5) (v t = (2kBT e /m 0 ) 1/2 , co c = qB/m 0 , and m 0 is the electron rest mass) for frequencies near the fundamental cyclotron frequency, for near-perpendicular emission. (For the Doppler regime, where N| >vt/c, Eq.…”

The contribution of plasma dielectric properties to the cyclotron radiation spectrum from a tokamak plasma

“…In addition, since a N p ~ g 2 , the absorption coefficient is proportional to g" 2 , and the scaling is inverted from the low-density result. This has been discussed by Fidone et al [6] and by Bornatici and Engelmann [7,8].…”

“…where /u = m o c 2 /kT e , this resonant denominator can no longer be approximated by to -£co B , and a relativistically correct treatment is necessary [7]. Dnestrovskii, et al [4] have shown that the values of the dielectric-tensor elements differ from those calculated by the non-relativistic approach only at the first harmonic (both modes) and the secondharmonic extraordinary mode.…”

“…Consider first the fundamental harmonic. Fidone et al [6] and Bornatici and Engelmann [7,8] have calculated the optical constants for the first harmonic for a weakly relativistic (JU > 1) plasma in thermal equilibrium. Using the Kirchoff relation and the results of Bornatici and Engelmann [8], the absorption coefficient for the first harmonic can be expressed as 1 2-2 4 S * where F is defined by The correct expression for the second-harmonic extraordinary mode absorption coefficient has not as yet been derived.…”

Momentum-space diffusion due to resonant wave–wave scattering of electromagnetic and electrostatic waves in a relativistic magnetized plasma

“…Nonlinear effects associated with relativistic electron-mass variation and the pondermotive force in unmagnetized as well as magnetized plasmas have been studied by many authors (Stenflo 1976;Kotsarenko 1977;Stenflo & Tsintsadze 1979;Nishikawa et al 1980;Papuashvili et al 1980Papuashvili et al , 1985Tsintsadze et al 1980;Berezhiani & Tskhakaya 1981;Shukla et al 1986). Furthermore, linear absorption and the dispersion relation in a relativistic magnetized plasma (Trubnikov 1959;Bornatici & Engelmann 1979;Cairns & Lashmore-Davies 1982) and quasi-linear and nonlinear wave-wave interactions in a magnetized plasma containing a relativistic electron beam or intermixed by energetic losscone electrons (Aizatskii 1980;Miroshnichenko 1980;Okazaki & Kato 1980;Ziebell & Yoon 1995) have been analysed theoretically, taking relativistic effects into account. In particular, it is very important to study kinetic effects due to nonlinear wave phenomena in a relativistic plasma, since these are related to relativistic electron beam acceleration (Sugaya 1993(Sugaya , 1994 and to energy and momentum transport in a fusion plasma.…”