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in subjects: "Electron Temperature"

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The multipulse Thomson scattering diagnostic on the DIII-D tokamak

This paper describes the design and operation of a 40-spatial channel Thomson scattering system that uses multiple 20 Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. Interference filter polychromators disperse the scattered light which is detected by silicon avalanche photodiodes. The measurable temperature range from 10 eV to 20 keV and the minimum detectable density is about 2 {times} 10{sup 18} m{sup {minus}3}. Las… more

Date: September 1, 1991

Creator: Carlstrom, T. N.; Campbell, G. L.; DeBoo, J. C.; Evanko, R. G.; Evans, J.; Greenfield, C. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Murakami density limit in tokamaks and reversed-field pinches

A theoretical upper limit for the density in an ohmically heated tokamak discharge follows from the requirement that the ohmic heating power deposited in the central current-carrying channel exceed the impurity radiative cooling in this critical region. A compact summary of our results gives this limit n/sub M/ for the central density as n/sub M/ = (Z/sub e//(Z/sub e/-1)/sup 1/2/n/sub eo/ (B/sub T//1T)(1m/R) where n/sub eo/ depends strongly on the impurity species and is remarkably independent … more

Date: March 1, 1984

Creator: Perkins, F.W. & Hulse, R.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Emission in the 50-80 A region from highly ionized silver in PLT tokamak plasmas

The spectrum of silver emitted by Princeton Large Torus (PLT) tokamak plasmas has been recorded in the 25 to 150 A region by a multichannel time-resolving grazing-incidence spectrometer. Silver atoms have been introduced in the tokamak plasma using the laser blow-off technique. For the first time, lines emitted within the 3p-3d transitions of Ag XXIX, Ag XXX, and Ag XXXI ions, between 50 and 80 A, have been identified.

Date: September 1, 1985

Creator: Schwob, J.L.; Wouters, A.; Suckewer, S.; Cohen, S.A. & Finkenthal, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron heating and confinemet measurements in EBT-S using Thomson scattering

Thomson scattering of ruby laser light was used to measure electron temperatures and densities in the ELMO Bumpy Torus-Scale (EBT-S) at Oak Ridge National Laboratory. The measurements were made primarily during May 1980, although some were taken during January 1980. The scattering system, which was designed for very low electron density measurements, features a 14-J ruby laser, a high-throughput spectrometer, and 15% quantum efficiency photomultipliers. The measured electron densities lie in th… more

Date: September 1, 1980

Creator: Bighel, L. & Cobble, J. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Analytical theory of ion-temperature-gradient instability

The relationship between the threshold values of ion-temperature-gradient instabilities and the temperature parameters of plasmas is investigated analytically in slab and toroidal geometries separately. It is found that the threshold values increase rapidly when the ion temperature becomes much higher than the electron temperature. The change of the threshold vaues with respect to the ion temperature is quite similar for both geometric models. This finding is consistent with PLT observations. F… more

Date: January 19, 1982

Creator: Guo, S.; Shen, J.; Chen, L. & Tsai, S.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Recent beam probe measurements on EBT, TMX, and RENTOR

It is noted that beam probe systems can provide accurate, reliable measurments of plasma space potential and nf(T/sub e/). Over some temperature range, at least, it should be possible to separate n and T/sub e/ by measuring the multiple ionization reaction products. It is also an ideal diagnostic for studying fluctuations since it provides a simultaneous measurement of phi and nf(T/sub e/) from the same point in the plasma and the measurements are continuous in time. Measurements can be made qu… more

Date: June 1, 1980

Creator: Hickok, R. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Time-resolved x-ray line diagnostics of laser-produced plasmas

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 ..mu..m light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers whose Z's range from 13 to 22 are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the ti… more

Date: January 1, 1982

Creator: Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D. & Lee, R.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Profile correction to electron temperature and enhancement factor in soft x-ray pulse-height-analysis measurements in tokamaks

Because soft x-ray pulse-height-analysis (PHA) spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. Assuming that the profile Ansatz for the electron temperature and density is of the form n/sub eo/(1-(ra)/sup 2/)/sup ..cap alpha../ and kT/sub eo/(1--(ra)/sup 2/)/sup ..beta../, we obtain the correction factors for the electron temperature and the enhancement factor as a function of the prof… more

Date: April 1, 1988

Creator: Sesnic, S.; Diesso, M.; Hill, K.; Holland, A. & Pohl, F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Analysis of x-ray production in TMX upgrade

TMX Upgrade (TMX-U), a tandem mirror experiment at LLNL, will use high power microwaves for electron cyclotron resonant heating (ECRH). As demonstrated on Elmo Bumpy Torus (EBT) and related experiments which use similar heating techniques, high energy electron populations are created. In these devices, which run CW, significant x-ray production occurs and adequate shielding must be provided for personnel protection. TMX-U is a pulsed experiment; however, significant x-ray production is expected… more

Date: February 4, 1982

Creator: Stallard, B. & Stephens, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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ORNL TNS program: microwave start-up of tokamak plasmas near electron cyclotron and upper hybrid resonances

The scenario of toroidal plasma start-up with microwave initiation and heating near the electron cyclotron frequency is suggested and examined here. We assume microwave irradiation from the high field side and an anomalously large absorption of the extraordinary waves near the upper hybrid resonance. The dominant electron energy losses are assumed to be due to magnetic field curvature and parallel drifts, ionization of neutrals, cooling by ions, and radiation by low Z impurities. It is shown by… more

Date: December 1, 1977

Creator: Peng, Y. K. M. & Borowski, S. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Results and analysis of the TMX electron-beam injection experiments

Electron beams (e-beams) were injected into the Tandem Mirror Experiment (TMX) plasma in order to investigate the effect on the ion cyclotron fluctuations of the plasma. The power level of the e-beams was comparable to that of the injected neutral beams. It was found that injection of the e-beams produced no significant effect on the ion cyclotron fluctuations, the measured plasma parameters, or the particle and power flow of the plasma. The increase in bulk electron temperature and the product… more

Date: August 1, 1980

Creator: Poulsen, P. & Grubb, D.P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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ICRF (Ion Cyclotron Range of Frequencies) edge modeling studies

Theoretical models have been developed, and are currently being refined, to explain the edge plasma-antenna interaction that occurs during ICRF heating. The periodic structure of a Faraday shielded antenna is found to result in strong ponderomotive force in the vicinity of the antenna. A fluid model, which incorporates the ponderomotive force, shows an increase in transport to the Faraday shield. A kinetic model shows that the strong antenna near fields act to increase the energy of deuterons w… more

Date: January 1, 1989

Creator: Lehrman, I.S. (Grumman Aerospace Corp., Princeton, NJ (USA). Corporate Research Center) & Colestock, P.L. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measuring the electron heat diffusion coefficient in a tokamak from Sawtooth oscillation observations

A number of new methods are discussed for determining the electron heat conduction coefficient chi/sub e/ in a tokamak from the experimental observation of the space-time evolution of the temperature perturbations induced by internal disruptions. In the Oak Ridge Tokamak (ORMAK) the various average values of chi/sub e/ and the radial dependence of chi/sub e/ are found to be consistent with and more precise than the chi/sub e/ (r) determined by conventionally analyzing the electron power balance… more

Date: February 1, 1978

Creator: Soler, M. & Callen, J. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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ECH propagation and absorption experiments at 140 GHz in MTX

Single pass absorption experiments using fundamental, O-mode ECH waves have been performed in the Microwave Tokamak Experiment (MTX) and found to be consistent with linear absorption theory, as predicted for the ECH source which is a 140 GHz, 400 kW CW gyrotron. These experiments provide the basis for comparison with future Free Electron Laser (FEL) experiments in which the absorption is predicted to be in the non-linear regime for P{sub FEL} {ge} 1 GW. The gyrotron power is coupled into a quas… more

Date: August 1, 1991

Creator: Fenstermacher, M. E.; Allen, S. L.; Casper, T. A.; Foote, J. H.; Hooper, E. B.; Johnston, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Direct electron heating by 60 MHz fast waves on DIII-D

Efficient direct electron heating by fast waves has been observed on the DIII-D tokamak. A four strap antenna with (0,{pi},0,{pi}) phasing launched up to 1.6 MW of fast wave power with {vert bar}n{sub {parallel}}{vert bar} {approx} 11. This {vert bar}n{sub {parallel}}{vert bar} is suitable for strong electron interaction in ohmic target plasmas (T{sub e} {le} 2 keV). Ion cyclotron absorption was minimized by keeping the hydrogen fraction low ({lt}3%) in deuterium discharges and by operating at … more

Date: October 1, 1991

Creator: Petty, C. C.; Pinsker, R. I.; Mayberry, M. J.; Chiu, S. C.; Luce, T. C.; Prater, R. (General Atomics, San Diego, CA (United States)) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurements of ICRF (ion cyclotron range of frequencies) loading with a ridged waveguide coupler on PLT

An ICRF ridged waveguide coupler has been installed on PLT for measurements of plasma loading. The coupler was partially filled with TiO/sub 2/ dielectric in order to sufficiently lower the cutoff frequency and utilized a tapered ridge for improved matching. Vacuum field measurements indicated a single propagating mode in the coupler and emphasized the importance of considering the fringing fields at the mouth of the waveguide. Low power experiments were carried out at 72.6 and 95.0 MHz without… more

Date: November 1, 1987

Creator: Greene, G. J.; Wilson, J. R.; Colestock, P. L.; Fortgang, C. M.; Hosea, J. C.; Hwang, D. Q. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Alfven wave stability in D-III-D

Within the framework of the global Alfven eigenmode theory in a cylindrical background plasma, I examine the excitation of global Alfven eigenmodes by intense neutral beam injection in the D III-D tokamak operating at General Atomics. I have considered two separate sets of experimental conditions, a low power'' set of cases using 10MW of hydrogen beams, and a high power'' shot of 20MW of deuterium beams. My results are particularly sensitive to the background density profile. For parabolic back… more

Date: September 1, 1989

Creator: Campbell, R.B. (Lawrence Livermore National Lab., CA (USA)) & Samec, T.K. (TRW, Inc., Redondo Beach, CA (USA))

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Direct electron absorption of fast waves on the D3-D tokamak

No Description Available.

Date: June 1, 1992

Creator: Petty, C. C.; Pinsker, R. I.; Chiu, S. C.; deGrassie, J. S.; Lohr, J.; Luce, T. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron cyclotron heating in tokamaks

Tokamaks may be efficiently heated at electron cyclotron resonance by launching of the extraordinary wave from the inside of the torus with a simple waveguide aperture. For typical tokamak parameters, 90% of the incident energy is absorbed in one traversal of the resonant surface. There is an effective maximum density for linear heating at the point where the plasma frequency is equal to the cyclotron frequency. The bulk of the plasma electrons is heated, increasing the perpendicular energy wit… more

Date: November 1, 1977

Creator: Eldridge, O.; Namkung, W. & England, A. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Princeton Plasma Physics Laboratory:

This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and … more

Date: January 1, 1986

Creator: Phillips, C.A. (ed.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Design and operation of the multipulse Thomson scattering diagnostic on DIII-D

This paper describes the design and operation of a 40 spatial channel Thomson scattering system that uses multiple 20 Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. As many as eight lasers may be fired alternately for an average measurement frequency of 160 Hz, or they may be fired in rapid succession (< 10 kHz), producing a burst of pulses for measuring transient events. The high spatial resolution (1.3 cm) and wide… more

Date: March 1, 1992

Creator: Carlstrom, T. N.; Campbell, G. L.; DeBoo, J. C.; Evanko, R.; Greenfield, C. M.; Haskovec, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Sources of hot electrons in laser-plasma interaction with emphasis on Raman and turbulence absorption

Heating targets with high power lasers results in a sizable fraction of the absorbed energy going into electrons of temperature much greater than thermal which can pre-heat the pellet core and accelerate fast ion blowoff which results in poor momentum transfer and hence poor compression efficiency. The present emphasis is to build lasers of higher frequency, ..omega../sub 0/, which at the same W/cm/sup 2/ results in more absorption into cooler electrons. Two physical reasons are that the laser … more

Date: April 6, 1982

Creator: Estabrook, K.; Kruer, W. L.; Phillion, D. W.; Turner, R. E. & Campbell, E. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurement of the central ion and electron temperature of tokamak plasmas from the x-ray line radiation of high-Z impurity ions

This paper describes measurements of the central ion and electron temperature of tokamak plasmas from the observation of the 1s - 2p resonance lines, and the associated dielectronic (1s/sup 2/nl - 1s2pnl, with n greater than or equal to 2) satellites, of helium-like iron (Fe XXV) and titanium (Ti XXI). The satellite to resonance line ratios are very sensitive to the electron temperature and are used as an electron temperature diagnostic. The ion temperature is deduced from the Doppler width of … more

Date: April 1, 1982

Creator: Bitter, M.; Von Goeler, S.; Goldman, M.; Hill, K.W.; Horton, R.; Roney, W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Advanced-fueled fusion reactors suitable for direct energy conversion. Fourth quarterly progress report: October 1976--December 1976 and first quarterly progress report: January 1977--March 1977

The direct energy conversion efficiencies calculated for Cat-D and D-/sup 3/He fueled Tokamak reactors are summarized over a range of reactor designs, collector configurations, assumed T/sub e//T/sub i/ ratios, and power densities. The performance of a system of superconducting coils that produce those fields required to guide escaping plasma along the path between the bundle divertor coils and the direct converter is also discussed.

Date: September 9, 1977

Creator: Blum, A. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department