Experimental demonstration of the amplification of electrostatic ion-cyclotron waves in a plasma with parallel ion flow shear but no magnetic-field-aligned electron current is presented. Waves with frequencies near the ion gyrofrequency and multiple harmonics launched from an antenna are observed to grow in amplitude in a region of ion flow shear. Amplification of multiple cyclotron harmonics w...

Electron acoustic waves (EAW) with a phase velocity less than twice the plasma thermal velocity are observed on pure ion plasma columns. At low excitation amplitudes, the EAW frequencies agree with theory, but at moderate excitation the EAW is more frequency variable than typical Langmuir waves, and at large excitations resonance is observed over a broad range. Laser induced fluorescence measur...

This paper summarizes the theoretical and numerical results we have obtained for the excitation and propagation of electron Bernstein waves in spherical tokamak plasmas. INTRODUCTION In the electron cyclotron range of frequencies the high-β NSTX and MAST plasmas are overdense to the traditional extraordinary X mode and/or the ordinary O mode. For low harmonics of the electron cyclotron frequenc...

We report direct high resolution observation of nonlinear steepened plasma waves excited in the wake of an intense, self-pinched electron beam. Oscillations in both accelerating and deflecting fields are measured, and analyzed in the context of linear and nonlinear plasma wave theory. The degree of nonlinearity in the wakr-fields is shown to be consistent with analytical predictions of the beam...

The launching of high-frequency electromagnetic waves into fusion plasmas is an effective method for plasma heating and noninductive current drive. In addition, the reflection of electromagnetic waves on the plasma cutoffs is utilized in electron density diagnostic measurements. The scope of this article is to comment on the standard approximations made in the simulation of electron-cyclotron w...

An electron distribution with a temperature anisotropy T‖/T⊥ > 1 can lead to the Electron Firehose instability (Here ‖ and ⊥ denote directions relative to the background magnetic field B0). Since possible particle acceleration mechanisms in solar flares exhibit a preference of energizing particles in parallel direction, such an anisotropy is expected during the impulsive phase of a flare. The p...

The transmission of electromagnetic waves across a thin plasma layer whose width is comparable to the wavelength of an incident wave is studied. The transmittances of transverse electric and transverse magnetic modes for both underdense and overdense plasmas are obtained as a function of the angle of incidence. It is thought that the significant reduction of transmittance in overdense plasma’s ...

Collective Thomson scattering is theoretically investigated with the inclusion of the relativistic correction of (v/c) 2. The correction is rather small for the plasma parameters inferred from the spectra of the thermal electron plasma waves in the plasma. Since the full formula of the corrected result is rather complicated, a simplified one is derived for practical use, which is shown to be in...