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1 - Nuclear Sciences and Applications - IAEA

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<strong>IAEA</strong>-CN-50/E-IV-5<br />

EXPERIMENTS ON EFFECTIVENESS OF MODE<br />

CONTROLLED ICRF FOR BOTH AXISYMMETRIC<br />

MIRRORS AND TOKAMAKS<br />

Y. YASAKA, H. TAKENO, S. INOUE, R. ITATANI<br />

Department of Electronics,<br />

Kyoto University,<br />

Kyoto,<br />

Japan<br />

Abstract<br />

EXPERIMENTS ON EFFECTIVENESS OF MODE CONTROLLED ICRF FOR BOTH AXISYM-<br />

METRIC MIRRORS AND TOKAMAKS.<br />

The paper describes two experimental topics: the effectiveness of mode controlled ICRF in mirrors<br />

<strong>and</strong> in tokamaks. High density (> 10 13 cm" 3 ) plasmas have been produced <strong>and</strong> MHD stabilized by<br />

a mode controlled helicon/fast wave <strong>and</strong> heated by a shear AlfV6n wave which is mode converted from<br />

the helicon/fast wave at the hybrid resonance in the HIEI mirror. Poloidal phasing of ICRF antennas<br />

in the WT-2 <strong>and</strong> WT-3 tokamaks has resulted in an improvement of the loading resistance <strong>and</strong> heating<br />

performance over conventional antennas.<br />

1. INTRODUCTION<br />

Waves in the ion cyclotron range of frequencies (ICRF) have a variety of<br />

branches that interact with ions <strong>and</strong>/or electrons in different ways. It is, therefore,<br />

possible to choose a desired interaction in heating or control of plasmas by selecting<br />

a specific wave branch. More importantly, since the wavelength of the ICRF waves<br />

is comparable to the plasma size, the k spectrum of the wave can be controlled by<br />

tailoring the antenna vacuum spectrum, leading to optimization of the interaction. We<br />

have demonstrated the effectiveness of controlling the azimuthal k spectrum of the<br />

wave for slow wave heating [1,2] <strong>and</strong> RF stabilization of the flute modes [3,4].<br />

In the next section of this paper, it is shown that high density<br />

[(0.5-2) x 10 13 cm" 3 ] plasmas are effectively produced <strong>and</strong> heated by a mode controlled<br />

helicon/fast wave (H/FW) <strong>and</strong> its mode conversion into a shear Alfve'n wave<br />

(SAW). The concept of the HIEI t<strong>and</strong>em mirror <strong>and</strong> its first operation are presented<br />

in Section 3. In Section 4, we demonstrate that the poloidal phasing of ICRF antennas<br />

has improved the coupling <strong>and</strong> heating efficiencies over those of conventional<br />

antennas in tokamaks.<br />

727

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