Quasi-isodynamic Configuration with Poloidally Closed Contours of B
and Small Number of Periods

M.A. Samitov1), W.A. Cooper2), M.Yu. Isaev1), M.I. Mikhailov1), J. Nührenberg3),
V.D. Shafranov1), A.A. Subbotin1), K. Yamazaki4), R. Zille3)

1) Russian Research Centre "Kurchatov Institute", 123182, Moscow, Russia
2) Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, PPB, 1015 Lausanne, Switzerland
3)Max-Planck-Institute für Plasmaphysik, IPP-EURATOM Assosiation, Germany
4)National Institute for Fusion Science, Toki, 509-5292, Japan

The possibility to fulfill the quasi-isodynamicity condition [1] for all reflected particles for moderate (N=6) [2] and high (N=9) [3] numbers of periods was shown earlier by numerical optimization. It was demonstrated that the fulfillment of quasi-isodynamicity condition leads to significant improvement of long-time collisionless fast particle confinement. In the present report the same task is considered for a small number of periods, N=2. It is shown that for a spatial magnetic axis with sufficient deviation from a plane it is possible to satisfy the quasi-isodynamicity condition along with the Mercier and resistive modes stability criteria. A configuration with low average beta is studied, < β >≈ 0.02 - 0.03. Ballooning modes are still unstable in the configuration obtained so far. An effort will be made to elucidate the possibility to stabilize these modes.

References

[1]S. Gori, W. Lotz, J. Nührenberg, Theory of Fusion Plasmas (International School of Plasma Physics), Bologna: SIF (1996) 335.
[2]M.I. Mikhailov, V.D. Shafranov, A.A. Subbotin et.al., Nuclear Fusion 42 (2002) L23.
[3]V.D. Shafranov, W.A. Cooper, M.Yu. Isaev et al., 30th EPS Conf. on Controlled Fusion and Plasma Physics, St. Petersburg, (2003).

This work was supported by INTAS Grant No 99-00592; by the Russian-Germany agreement WTZ-RUS-01/581; by Russian Federal program on support of leading scientific school researches, Grant No 2024.2003.2; by the Russian Fund for Basic Research, Grant No 03-02-16768,; by the Fonds National Suisse de la Recherche Scientifique, Euratom; by Department of atomic science and technology, Minatom RF. One of the authors (M.I.M) would like to mention that he took part in this work during his stay in NIFS, Japan.