Search

Anomalously fast ion heating has been observed in the Caltech Encore tokamak [Phys. Rev. Lett. 59, 1436 (1987)], with the use of laser-induced fluorescence. This heating was found to be independent of electron temperature, but was well correlated with the presence of large-amplitude drift-Alfvén waves. Evidence is presented that suggests that the heating is stochastic and occurs when the ion displacement due to polarization drift becomes comparable to the perpendicular wavelength, i.e., when k⊥ (mik⊥ [lowercase_phi_synonym]0/qB2)∼1. Stochastic heating may also be the cause of the anomalously high ion temperatures observed in reversed-field pinches. [ABSTRACT FROM AUTHOR]

Electron temperature fluctuations have been investigated in the edge region of the Caltech research tokamak [S. J. Zweben and R. W. Gould, Nucl. Fusion 25, 171 (1985)], and an upper limit to this fluctuation level was found at &Ttilde;[sub e]/T[sub e] ... 15%. This measurement, together with previous measurements of density and electric and magnetic field fluctuations, allows a unique comparison of the heat transport resulting from three basic turbulent mechanisms: (1) heat flux from the particle flux resulting from microscopic density and electric field fluctuations; (2) thermal conduction resulting from microscopic temperature and electric field fluctuations; and (3) thermal conduction resulting from microscopic magnetic field fluctuations. The measurements indicate that, in the edge regions, the electron heat transport caused by the measured turbulence-induced particle flux is comparable to or greater than that caused by the thermal conduction associated with the electron temperature and electric field fluctuations, and is significantly greater than that resulting from the measured magnetic fluctuations. This electron heat loss caused by the plasma turbulence is found to be an important electron energy loss mechanism in the edge regions. [ABSTRACT FROM AUTHOR]

Assesses the feasibility of using laser induced fluorescence to obtain two-dimensional images of turbulent structures in plasma. Expected turbulence characteristics in the Magnetic Reconnection Experiment and on the National Spherical Torus Experiment; Collisional radiative modeling of helium-like ions; Signal-to-noise ratio.

Describes the diagnostic capabilities of pellet charge exchange demonstrated on the Tokamak Fusion Test Reactor (TFTR) and discusses the prospects for applying this technique to the International Thermonuclear Experimental Reactor. Energy distribution of alpha particles in the plasma core of quiescent TFTR discharges; Beneficial effects of impurity pellets in tokamaks.

Presents a summary of the experience with the alpha charge exchange recombination spectroscopy (alpha-CHERS) and pellet charge exchange confined, nonthermal alpha particle diagnostics over the first two years of Tokamak test fusion reactor D-T operation. Concept, instrumentation and analysis of alpha-CHERS; Examples of alpha-CHERS measurements.

Describes the status of the pellet charge exchange (PCX) diagnostic used on the Tokamak Fusion Test Reactor and discusses the results from radio frequency experiments investigating the heating of L-mode deuterium-tritium plasmas in the second-harmonic tritium cyclotron frequency regime. Measurement of tritium tail ions; Main components of the PCX; System of operation.

The polarization of the π component of the Zeeman split Li2P-2S transition allows a direct spectroscopic measurement of the local magnetic pitch angle. Li atoms are injected radially into TEXT as a 95 keV beam and the intensity of the transmitted beam is detected. A polarization-modulated, cavity-dumped dye laser, tuned into resonance with the π line, is injected collinearly with the beam. Laser excitation of the beam results in an enhanced beam attenuation. Time-resolved detection of the transmitted Li beam allows determination of the local magnetic pitch angle. Details orr the system and results of recent measurements will be discussed. [ABSTRACT FROM AUTHOR]

Charge exchange interactions of alpha particles with the ablation cloud surrounding an injected carbon pellet can be used to measure the energy spectrum of the incident fast confined alpha particles in a fusion plasma. Measurement of helium neutrals from He[sup 2+] + C[sup 4+] → He[sup 0] + C[sup 6+] interactions appears to be the most attractive option. This paper describes progress on developing this diagnostic including measurements during pellet injection into the TEXT tokamak. [ABSTRACT FROM AUTHOR]