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Volume 55 (1986)
- Issue 6 Pages 449-
- Issue 5 Pages 391-
- Issue 4 Pages 311-
- Issue 3 Pages 243-
- Issue 2 Pages 111-
- Issue 1 Pages 6-
Volume 55, Issue 5
Displaying 1-3 of 3 articles from this issue
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Kosuke Okamoto1986 Volume 55 Issue 5 Pages 391-411
Published: May 20, 1986
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSVacuum technology on a mirror type engineering test reactor on the model of the Tandem Mirror Technology Demonstration Facility (TDF) designed at Lawrence Livermore National Laboratory is described. The vacuum technology used in mirror type machine is remarkably different from that in torus type one.View full abstractDownload PDF (1888K) -
Kenro Miyamoto, Osamu Naito1986 Volume 55 Issue 5 Pages 412-419
Published: May 20, 1986
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSAnalytical results of Θ pumping for the tokamak current drive are presented. Diffusion of externally applied oscillating electric field into the tokamak plasma is examined when the plasma is normal. When the oscillating electric field is parallel to the stationary toroidal plasma current and the induced current density by the applied electric field becomes larger than the average density of the toroidal plasma current over the plasma cross section, the radial profile of the safety factor has the extremum near the plasma boundary region and MHD instabilities are excited. It is assumed that anomalous diffusion of the induced current localized in the plasma boundary region takes place, so that the extreme value in the radial profile of the safety factor disappears. The anomalously diffused electric field due to this relaxation process has net d. c component and its non-zero value of the time average is estimated. Then the condition of the tokamak current drive by Θ pumping is derived. Some numerical results are presented for an example of a fusion grade plasma.View full abstractDownload PDF (598K) -
Shuichi Takamura, Noriyasu Ohnishi, Hiroyuki Yamada, Takayoshi Okuda1986 Volume 55 Issue 5 Pages 420-430
Published: May 20, 1986
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSErgodic magnetic limiter has been conceived as a concept of impurity control for an advanced tokamak. The structure of magnetic field line in the so-called ergodic layer is quite important for the particle and heat transport there. In this note ergodization of magnetic field line is studied in terms of island overlapping for both local and nonlocal helical windings using a field line tracing computer code.
A helical winding of mode index m/n, m and n are poloidal and toroidal mode numbers, on the torus chamber generates a number of sidebands in addition to the main helical mode m/n through the generation of higher harmonics from filamentary coil current and the toroidicity. The contribution from the latter was analyzed by Morozov and Solov'ev and has been considered small and neglected. However is our finding that the sideband generation by toroidicity from pure helical field on the cylinder is comparable to the higher harmonics generation from filamentary coil.
It has been thought that the ergodization comes from the island overlapping of the main and the first sideband modes. We found, however, that the island overlapping of higher sideband modes is the origin of ergodization if we have the higher order rational surfaces in the exterior to the first sideband resonance layer and that the helical field is weak.
Finally we note that an ergodized layer does not extend close to the chamber wall when the helical coils are wound on the chamber wall. Therefore the heat and particle flux is not uniform on the wall but localized. In order to improve heat load pattern on the wall and particle removal, we propose the scheme of rotating ergodic layer associated with a pump limiter.View full abstractDownload PDF (1076K)
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