Toroidal Plasma Current Startup and Sustainment by rf in the WT-2 Tokamak

Kubo, S.; Nakamura, Masahiko; Cho, T.; Nakao, S.; Shimozuma, Τ.; Andõ, Akira; Ogura, K.; Maekawa, Takashi; Terumichi, Y.; Tanaka, Shigetoshi

doi:10.1103/physrevlett.50.1994

Cited by 98 publications

(60 citation statements)

References 13 publications

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“…The required electric fields for the breakdown are also increased with the frequency of the EC wave since the electrons can't get sufficient energy to ionize the neutral gas in the case of higher frequencies. In the WT-2 the required power for the breakdown was lower than 30 kW at a frequency of 35.6 GHz [9], whereas in the TRIAM the required power was higher than 40 kW.…”

Section: Discussionmentioning

confidence: 99%

Plasma Experiments Using a New 170 GHz EC System and a Simple Model for Plasma Production on the TRIAM-1M

Hasegawa

Hanada

Itoh

et al. 2004

J. Plasma Fusion Res.

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An electron cyclotron heating (ECH) system has been installed on the TRIAM-1M tokamak, which produces a 170 GHz microwave up to 260 kW at the window of the gyrotron for 5 sec. After the Matching Optical Unit (MOU) converts the microwave to a Gaussian beam, a microwave power of 200 kW is transmitted by a corrugated waveguide of 63.5 mm in diameter. Tests confirmed these specifications, and the fundamental ordinary electron cyclotron (EC) wave of 170 GHz up to 120 kW was injected into the vacuum vessel of the TRIAM-1M in order to ionize neutral hydrogen gas to make source plasma, which is expected to reduce flux consumption in the case of current start-up by means of Ohmic heating (OH) coils. Though the breakdown does not occur at the input RF power, P RF = 40 kW with the neutral gas pressure, p = 1.3 × 10 -3 Pa, high-density plasma (more than 0.7 × 10 19 m -3 ) is produced at P RF = 100 kW. In the range of P RF = 40-100 kW, the electron density is proportional to P RF .

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Section: Discussionmentioning

confidence: 99%

Plasma Experiments Using a New 170 GHz EC System and a Simple Model for Plasma Production on the TRIAM-1M

Hasegawa

Hanada

Itoh

et al. 2004

J. Plasma Fusion Res.

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“…There are experimental results of RF being used to increase the plasma current in a toroidal device on WT-2 [16], TII-U [17], PLT [18][19], Alcator-C [20], and CDX-U [21][22]. The results of the first five of these are summarized in Table 2, while those in CDX-U are more difficult to interpret for the reasons stated below.…”

Section: Relation To Experimentsmentioning

confidence: 93%

Time-Scales for Non-Inductive Current Buildup in Low-Aspect-Ratio Toroidal Geometry

Jardin¹

1999

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The fundamental differences between inductive and non-inductive current buildup are clarified and the associated time-scales and other implications are discussed. A simulation is presented whereby the plasma current in a low-aspect-ratio torus is increased primarily by the self-generated bootstrap current with only 10% coming from external current drive. The maximum obtainable plasma current by this process is shown to scale with the toroidal field strength. The basic physics setting the time-scales can be obtained from a 1D analysis. Comparisons are made between the timescales found here and those reported in the experimental literature.2

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“…2. Particularly key, early tokamak experiments came on the WT-2 tokamak in Kyoto [18,19] and the JFT-2 (JAERI Fusion Torus)) tokamak in Tokai [20], the JIPP T-II torus in Nagoya [21], and Versator [22] and Alcator [23] experiments at MIT. A very key series of experiments was conducted on the PLT device at Princeton [24].…”

Section: Past: the Current Drive Effectmentioning

confidence: 99%

Pushing Particles with Waves: Current Drive and <i>α</i>-Channeling

Fisch

2016

Plasma and Fusion Research

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It can be advantageous to push particles with waves in tokamaks or other magnetic confinement devices, relying on wave-particle resonances to accomplish specific goals. Waves that damp on electrons or ions in toroidal fusion devises can drive currents if the waves are launched with toroidal asymmetry. Theses currents are important for tokamaks, since they operate in the absence of an electric field with curl, enabling steady state operation. The lower hybrid wave and the electron cyclotron wave have been demonstrated to drive significant currents. Noninductive current also stabilizes deleterious tearing modes. Waves can also be used to broker the energy transfer between energetic alpha particles and the background plasma. Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled instead into useful energy, that heats fuel ions or drives current. An important question is the extent to which these effects can be accomplished together.

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Toroidal Plasma Current Startup and Sustainment by rf in the WT-2 Tokamak

Cited by 98 publications

References 13 publications

Plasma Experiments Using a New 170 GHz EC System and a Simple Model for Plasma Production on the TRIAM-1M

Plasma Experiments Using a New 170 GHz EC System and a Simple Model for Plasma Production on the TRIAM-1M

Time-Scales for Non-Inductive Current Buildup in Low-Aspect-Ratio Toroidal Geometry

Pushing Particles with Waves: Current Drive and <i>α</i>-Channeling

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