Emission of electron Bernstein waves in plasmas

Ram, A. K.; Bers, A.; Lashmore-Davies, C. N.

doi:10.1063/1.1429634

Cited by 42 publications

(51 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The optimum X-B process occurs closer to the edge of the plasma than the optimum O-X-B conversion. A more detailed analysis based on a kinetic treatment of the EBW in sheared magnetic fields confirms the basic results of the analysis given above [1,4]. We have also studied the propagation of EBW rays in model NSTX profiles.…”

Section: Excitation and Propagation Of Ebwssupporting

confidence: 55%

See 1 more Smart Citation

On electron Bernstein waves in spherical tori

Ram¹,

Decker²,

Peysson

2005

J. Plasma Phys.

View full text Add to dashboard Cite

show abstract

Section: Excitation and Propagation Of Ebwssupporting

confidence: 55%

“…However, in order for the O mode power not to get reflected back out on the X mode requires that η > 1 [1,4]. From (8) we find that this condition is satisfied when the density scalelength is long.…”

Section: Excitation and Propagation Of Ebwsmentioning

confidence: 76%

On electron Bernstein waves in spherical tori

Ram¹,

Decker²,

Peysson

2005

J. Plasma Phys.

View full text Add to dashboard Cite

show abstract

“…A number of experiments have studied this emission of EBWs in spherical tori [4,5,6,7,8]. We have also shown that the mode conversion coefficients for EBW emission are directly related to the mode conversion coefficients for the excitation of EBWs by sources external to the plasma [9,10]. This will be illustrated through results obtained from numerical solutions of a full-wave kinteic description of mode conversion among EBW and the X and O modes.…”

Section: Ebws In the Vicinity Of The Upper Hybrid Resonance (Uhr) Thmentioning

confidence: 89%

“…Furthermore, we will explicitly include the poloidal magnetic field as this forms an important component of the mode conversion equations in a ST plasma. The development of the approximate kinetic analysis has been detailed previously [3,9,13]. Here we just provide the basic equations for completeness.…”

Section: Excitation Of Electron Bernstein Waves -Kinetic Plasma Modelmentioning

confidence: 99%

Excitation and emission of electron cyclotron waves in spherical tori

Ram

Bers

2003

Nucl. Fusion

View full text Add to dashboard Cite

Abstract. The conventional ordinary and extraordinary modes in the electron cyclotron range of frequencies are not suitable for heating of and/or driving currents in spherical tori (ST) plasmas. However, electron Bernstein waves offer an attractive possibility for heating and current drive in this range of frequencies. In this paper, we summarize our theoretical and numerical results which describe the excitation of electron Bernstein waves in ST plasmas when the extraordinary mode or the ordinary mode are coupled into the plasma from an external source. In our discussion on the conversion of the ordinary mode to electron Bernstein waves (via the slow extraordinary mode) we illustrate very important physics, relevant to this conversion process, that has been ignored in previous studies. The particular physics has to do with the conversion of the slow extraordinary mode to the fast extraordinary mode that can then propagate out of the plasma and thus reduce the mode conversion to electron Bernstein waves. This reduction in the mode conversion can occur even when the wave numbers are such that the ordinary mode cutoff and the slow extraordinary mode cutoff are coincident in space. Furthermore, we also consider the emission of electron Bernstein waves from a thermal plasma. This emission mode converts to extraordinary and ordinary modes in the vicinity of the upper hybrid resonance. We describe the general relationship between the conversion coefficients when exciting electron Bernstein waves using either the extraordinary mode or the ordinary mode, and the emission coefficients when thermally emitted electron Bernstein waves convert to the extraordinary and ordinary modes.

show abstract

“…EBWs are particularly suitable for heating and current drive in the high-β plasmas of spherical tori like the National Spherical Torus Experiment (NSTX) [5] and the Mega Amp Spherical Tokamak (MAST) [6], where ω p ω c over most of the plasma. There have been a number of theoretical works on the EBW dispersion relation [7] [8] [9], on mode conversion to EBWs [10] [11] [12], on emission of EBWs [13], and on current drive by EBWs [14]. However, a detailed study of the characteristics of EBWs and their resonant interaction with electrons has been lacking.…”

Section: Introductionmentioning

confidence: 99%

Relativistic description of electron Bernstein waves

Decker

Ram

2006

Physics of Plasmas

View full text Add to dashboard Cite

The application of the extraordinary and ordinary electron cyclotron waves for heating and current drive in overdense, magnetized plasmas is restricted. For frequencies near low harmonics of the electron cyclotron frequency these waves are cutoff near the edge of the plasma. For higher frequencies the interaction of the waves with electrons is weak leading to very low absorption of wave power. However, electron Bernstein waves provide means for heating and current drive in overdense plasmas since they have no density cutoffs and are strongly damped near harmonics of the electron cyclotron resonance. This paper discusses properties of electron Bernstein waves that make them an attractive means for delivering energy and momentum to electrons. An approximate analytical model for electrostatic waves in the weakly relativistic and weak damping limits is developed. From this model the propagation and damping characteristics of electron Bernstein waves and their dependence on plasma parameters are derived. It is found that relativistic effects are necessary to properly describe the resonant interaction of electron Bernstein waves with electrons. The characteristics of electron Bernstein wave propagation and damping are very different depending on whether the electron cyclotron harmonic resonance is approached from the low-or the high-field side. The results from the analytical model and the associated analysis agree well with the results from the exact numerical calculations. This validates the physics of the simplifying assumptions on which the model is based. The electron Bernstein waves are completely damped well before the electron cyclotron resonance due to the Doppler shift. Within the damping region the waves interact with suprathermal electrons thereby having the potential for efficient current drive.

show abstract

Emission of electron Bernstein waves in plasmas

Cited by 42 publications

References 4 publications

On electron Bernstein waves in spherical tori

On electron Bernstein waves in spherical tori

Excitation and emission of electron cyclotron waves in spherical tori

Relativistic description of electron Bernstein waves

Contact Info

Product

Resources

About