The effect of end-cell stability on the confinement of the central-cell plasma in TMX

Drake, R. P.; Casper, T. A.; Clauser, John F.; Coensgen, F.H.; Correll, D.L.; Cummins, W.F.; Davis, J.C.; Foote, J. H.; Futch, A.H.; Goodman, R.K.; Grubb, D. P.; Hornady, R.S.; Nexsen, W.E.; Simonen, T.C.; Stallard, B. W.

doi:10.1088/0029-5515/21/3/006

Cited by 25 publications

(17 citation statements)

References 6 publications

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“…The observed correlation between RF activity (V pp , sensed by electrostatic probes external to the central plasma) and the efficacy of plugging, as reflected by m c , is shown in Fig. 87, taken from the report of Drake et al [339]. It was found that the loss of confinement time due to RF activity could be modelled by an expression of the form [340] TABLE XIX.…”

Section: Fig 87 Tmx Data On Loss Of Plugging Caused By the Onset Of R...mentioning

confidence: 93%

The magnetic mirror approach to fusion

1987

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The magnetic mirror approach to fusion is reviewed in depth. Starting with a brief chronological history of the development of the basic mirror concept, its subsequent evolution into the tandem mirror, the field reversed mirror and other variants is described. Also discussed are the many-faceted aspects of mirror theory, including adiabatic invariants, MHD equilibrium and stability, collisional processes, transport theory and microinstability theory. The review concludes with an updating of experimental results, a discussion of mirror-related technology, including neutral beam injection and direct conversion, and a brief description of design studies of mirror fusion power plants.

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Section: Fig 87 Tmx Data On Loss Of Plugging Caused By the Onset Of R...mentioning

confidence: 93%

The magnetic mirror approach to fusion

1987

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“…This was eventually supported by Doppler broadening measurements which indicated that central cell ion temperatures might be as high as 100-200 eV [10]. Theory now indicates that radio-frequency (RF) fluctuations generated in the end cells couple to the central cell ions and heat them [11]. Increased RF fluctuations were also associated with decreased ion confinement in the central cell.…”

Section: Ii4 Major Results From Tmxmentioning

confidence: 94%

Study of impurities in the Tandem Mirror Experiment using extreme-ultraviolet spectroscopy

Strand¹

1982

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Impurities in the Tandem Mirror Experiment (TMX) have been studied using extreme ultraviolet spectroscopy. Three time-resolving absolutely-calibrated normal-incidence monochromators, one on each section of TMX, were used to study the impurity emissions in the wavelength range of 300 A -1600 A. The instruments on the east end cell and central cell were each capable of obtaining spatially-resolved profiles from 22 chords of the plasma simultaneously while the instrument on the west end cell monitored the central chord. The impurities identified in TMX were carbon, nitrogen, oxygen, and titanium. Emphasis was placed upon determining the impurity densities and radiated power losses of the central cell; results indicate that the impurity concentrations were low-less than 0.4% for each species-and that less than 10% of the total net trapped neutral beam power was lost to radiation. The use of titanium gettering on the central cell walls was observed to decrease the brightnesses of singly-and doubly-ionized carbon and oxygen in the central cell plasma. In the end cells, oxygen was the main impurity with a concentration of about 1.5% and was injected by the neutral beams; the other impurities had concentrations of about 0.5%. Radiated losses from the end cells were negligible.Evidence has been obtained which indicates that impurities in the central cell are subject to a radially outward transport. The density ratios of 0 V to 0 VI indicate a short (0.3-3 ms) central cell confinement time for 0 VI ions, even though calculations predict that axial confinement times should be longer than the TMX shot duration. Impurity puffing experiments performed in the central cell of TMX support this conclusion. Oxygen and neon puffed into the central cell during the TMX shot were observed to accumulate in the outer boundary of the plasma, while only a small fraction penetrated into the central regions. None of the injected impurity was observed in the end cell plasmas; instrumental sensitivity puts an upper limit of 0.03 on the ratio of injected impurity density in the end cells to that in the central cell. Oxygen puffed before the TMX shot was observed to decay from all regions of the plasma during the shot. These results provide an explanation for the observed low concentrations of impurities in the central cell of TMX.

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“…8 In these devices, external fueling is required not only to maintain the plasma density at elevated values but also to prevent the onset of end cell microinstabilities that degrade the central cell confinement. 17 …”

Section: Particle Transportmentioning

confidence: 99%

Fueling of magnetic confinement devices

Milora¹

1982

Journal of Vacuum Science and Technology

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A general overview of the fueling of magnetic confinement devices is presented, with particular emphasis on recent experimental results.Various practical fueling mechanisms are considered, such as cold gas inlet (or plasma edge fueling), neutral beam injection, and injection of high speed cryogenic hydrogen pellets. The central role played by charged particle transport and recycle of plasma particles from material surfaces in contact with the plasma is discussed briefly.The various aspects of hydrogen pellet injection are treated in detail, including applications to the production of high purity startup plasmas for stellarators and other devices, refueling of tokamak plasmas, pellet ablation theory, and rhe technology and performance characteristics of low and high speed pellet injectors.Research sponsored by the Office of Fusion Energy, U.S. Department of Energy, under contract W-7405-eng-26 with the Union Carbide Corporation.

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The effect of end-cell stability on the confinement of the central-cell plasma in TMX

Cited by 25 publications

References 6 publications

The magnetic mirror approach to fusion

The magnetic mirror approach to fusion

Study of impurities in the Tandem Mirror Experiment using extreme-ultraviolet spectroscopy

Fueling of magnetic confinement devices

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