Electron Cyclotron/Upper Hybrid Resonant Preionization in the ISX-B Tokamak PDF Download
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Author: R. M. Gilgenbach
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Languages : en
Pages : 34
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Preionization experiments have been performed on a tokamak by injecting about 80 kW of microwave power at 35 GHz for up to 15 ms. Microwave absorption occurs at the electron cyclotron and upper hybrid resonance frequencies as predicted by theory. Preionization causes substantial (40%) reductions in loop voltage during the initial phase of the tokamak shot. Flux (volt second) savings with preionization are about 30% in the first 2 ms or about 2% of the total flux expenditure in a tokamak shot. The plasma current starts 20 microsec earlier and rises 1.4 times more rapidly in the preionized case. Electron densities of 5 x 10 to the 12th power/cu cm can be sustained with only a toroidal magnetic field during microwave injection. The bulk electron temperature in the preionized plasma is about 10 eV although there are indications of higher electron temperatures (50 eV) in the upper hybrid resonance layer. During the early stages of ohmic heating the preionization is effective in decreasing the peak of the radiated power. (Author).
Author: R. M. Gilgenbach
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
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Book Description
Preionization experiments have been performed on a tokamak by injecting about 80 kW of microwave power at 35 GHz for up to 15 ms. Microwave absorption occurs at the electron cyclotron and upper hybrid resonance frequencies as predicted by theory. Preionization causes substantial (40%) reductions in loop voltage during the initial phase of the tokamak shot. Flux (volt second) savings with preionization are about 30% in the first 2 ms or about 2% of the total flux expenditure in a tokamak shot. The plasma current starts 20 microsec earlier and rises 1.4 times more rapidly in the preionized case. Electron densities of 5 x 10 to the 12th power/cu cm can be sustained with only a toroidal magnetic field during microwave injection. The bulk electron temperature in the preionized plasma is about 10 eV although there are indications of higher electron temperatures (50 eV) in the upper hybrid resonance layer. During the early stages of ohmic heating the preionization is effective in decreasing the peak of the radiated power. (Author).
Author:
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Languages : en
Pages :
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One experiment on electron cyclotron heating on the Impurity Study Experiment (ISX-b) tokamak has been completed and a second experiment is in progress. In the first experiment, with a gyrotron producing 100 kW at 35 GHz, a heating efficiency greater than 60% was achieved. Unpolarized radiation was launched from the high field side of the tokamak, heating electrons at cyclotron resonance in the center of the plasma. From laser scattering and thermal emission at the second gyroharmonic, the electron temperature, initially 850 eV, increased to 1250 eV at the end of a 15-ms pulse. The second experiment is now in progress, with 180 kW at 28 GHz and a capability of 100-ms pulses. A comparison between polarized and unpolarized radiation, modification of the plasma current profile, and a critical comparison with theory are planned. In this paper, experiments on preionization at the upper hybrid resonance are reported. A plasma with an electron temperature of 10 eV was produced, which is not high enough to reduce impurity radiation. The resistive part of the loop voltage was reduced by preionization. Plans for an experiment to measure electric current induced by electron cyclotron heating are presented, along with a review of the theoretical basis of the current drive.
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Category :
Languages : en
Pages : 29
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Category : Power resources
Languages : en
Pages : 538
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Category : Aeronautics
Languages : en
Pages : 748
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
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Category : Science
Languages : en
Pages : 248
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Category :
Languages : en
Pages : 17
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We report results of electron cyclotron heating (ECH) experiments in which 80-kW of microwave power from a 35-GHz gyrotron is injected into a tokamak with large single pass absorption. For 10-ms microwave pulses, incident from the high field side of the torus, the central electron temperature increases from 850 eV to 1250 eV, in agreement with empirical transport code calculations. For the first time in a tokamak, we demonstrate that electron temperature scales linearly with ECH power. (Author).
Author: (and others).
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Category :
Languages : en
Pages : 7
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Category : Infrared radiation
Languages : en
Pages : 336
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Category : Science
Languages : en
Pages : 978
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