3D Plasma Equilibrium and Stability with Hot Particle Anisotropic Pressure
- Ecole Polytechnique Federate de Lausanne, Centre de Recherches en Physique des Plasmas, Association Euratom-Suisse, CH1015 Lausanne (Switzerland)
- Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge TN37831 (United States)
- Max Planck Institur fuer Plasmaphysik, Garching (Germany)
- National Institute for Fusion Science, Oroschi-cho 322-6, Toki 509-5292 (Japan)
The anisotropic pressure free-boundary three-dimsnsional (3D) equilibrium code ANI-MEC with nested magnetic flux surfaces has been developed as an extension of the VMEC2000 code. The preconditioning algorithm included is exploited to allow the computation of equilibrium states with radial force balance error improvements exceeding 4 orders of magnitude compared with the non-conditioned results. Large off-axis energetic particle deposition has been applied in a 2-field period quasiaxisymmetric stellarator reactor at <{beta}>{approx_equal}4.5% to test the limitations of the code. The hot particle pressures are roughly uniform around the flux surfaces when p{sub parallel}>p{sub perpendicular}. The fast particle perpendicular pressures localise in the region of deposition for p{sub perpendicular}>p{sub parallel}, while the energetic particle parallel pressures concentrate on the low-field side. Two anisotropic pressure models for global fluid stability implemented in the TERPSICHORE code have been applied to the LHD Heliotron for a sequence of equilibria with fixed <{beta}{sub dia}>{approx_equal}5%(<{beta}{sub th}>{approx_equal}3.5%) varying the fast particle temperature ratio T{sub parallel}/T{sub perpendicular}. Global magnetohydrodynamic modes are quasi-stable according to the model with rigid hot particle layers, while they become stabilised according to the fully interacting energetic particle model with increasing T{sub parallel}/T{sub perpendicular}. As T{sub parallel}/T{sub perpendicular} approaches 3, however, the n = 1 mode family becomes unstable. A transition from a nearly stable quasi-external ballooning-interchange structure to a weakly unstable internal kink mode takes place. The investigation of beam-driven fusion in a Heliotron system is broached. A background plasma with cold ions and warm electrons at <{beta}{sub ith}>{approx_equal}1% is examined with fixed T{sub parallel}/T{sub perpendicular} = 10 in which the hot particle contribution to <{beta}> is increased. An equilibrium limit is reached when the hot parallel component <{beta}{sub parallel}{sup h}> exceeds 6.1%. The rigid model predicts stability, while the fully interacting model shows stabilisation for <{beta}{sub parallel}{sup h} greater than 3%.
- OSTI ID:
- 21251763
- Journal Information:
- AIP Conference Proceedings, Vol. 1069, Issue 1; Conference: Joint Varenna-Lausanne international workshop on theory of fusion plasmas, Varenna (Italy), 25-29 Aug 2008; Other Information: DOI: 10.1063/1.3033730; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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