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(EXP5/10) Summarized General Scaling Laws Covering over the Representative Tandem-Mirror Operations in Gamma 10

T. Cho¹⁾, M. Hirata¹⁾, H. Hojo¹⁾, M. Ichimura¹⁾, K. Ishii¹⁾, A. Itakura¹⁾, I. Katanuma¹⁾, J. Kohagura¹⁾, Y. Nakashima¹⁾, T. Saito¹⁾, S. Tanaka¹⁾, Y. Tatematsu¹⁾, M. Yoshikawa¹⁾, T. Tamano¹⁾, K. Yatsu¹⁾, S. Miyoshi^1)
 
1) Plasma Research Centre, University of Tsukuba, Ibaraki, Japan

Abstract.  Generalized scaling laws covering over the representative tandem-mirror operational modes from 1979 to 2000 in GAMMA 10 [i.e., characterized in terms of (i) a high-potential mode having kV-order ion-confining potentials ($\phi_{c}^{}$) and thermal-barrier potentials ($\phi_{b}^{}$), and (ii) a hot-ion mode yielding fusion neutrons with 10-20-keV bulk-ion temperatures] are found and summarized for providing the possibilities of combining the characteristics from each mode into novel extended operational modes. The physics scalings of the formation of the plasma confining potentials as well as the associated effects of the potentials on plasma-parameter improvements are systematically investigated as follows: (i) The potential-formation scalings in the two representative modes are consolidated and generalized on the basis of the consistency with the novel findings of wider validity of Cohen's strong electron-cyclotron heating (ECH) theory covering over both modes. (ii) The produced potentials, in turn, provide a favorable novel scaling of the increase in the central-cell electron temperatures T_e with increasing $\phi_{b}^{}$, limited by the available ECH powers. The scaling of T_e with $\phi_{b}^{}$ is well interpreted by the Pastukhov theory of plasma potential confinement, as a similarly reported scaling of potential-confined ion temperatures with $\phi_{c}^{}$. (iii) A scaling of $\phi_{c}^{}$ [kV] with ECH powers in a plug region, P_ECH [kW], and the central-cell densities, n_c [ 10¹⁸m^{- 3}], is summarized as $\phi_{c}^{}$ = 1.73×10^-4P_ECH^1.73exp(- 0.33n_c). (iv) Consequently, under the assumption of the validity of the extension of these theoretically well interpreted scaling data, the formation of Pastukhov's predicted $\phi_{c}^{}$ of 30 kV for confining Q = 1 plasmas is scaled to require 5-MW P_ECH.

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