Physics Considerations in the Design of NCSX
Authors: G.H. Neilson, M.C. Zarnstorff, L.P. Ku, E.A. Lazarus, P.K. Mioduszewski, M. Fenstermacher, E. Fredrickson, G.Y. Fu, A. Grossman, P.J. Heitzenroeder, R.H. Hatcher, S.P. Hirshman, S.R. Hudson, D.W. Johnson, H.W. Kugel, J.F. Lyon, R. Majeski, D.R. Mikkelsen, D.A. Monticello, B.E. Nelson, N. Pomphrey, W.T. Reiersen, A.H. Reiman, P.H. Rutherford, J.A. Schmidt, D.A. Spong, and D.J. Strickler
Date of PPPL Report: October 2002
Presented at: the Nineteenth IAEA Fusion Energy Conference in Lyon, France, October 14-19, 2002.
Compact stellarators have the potential to make steady-state, disruption-free magnetic fusion systems with beta ~5% and relatively low aspect ratio (R/<a> < 4.5) compared to most drift-optimized stellarators. Magnetic quasi-symmetry can be used to reduce orbit losses. The National Compact Stellarator Experiment (NCSX) is designed to test compact stellarator physics in a high-beta quasi-axisymmetric configuration and to determine the conditions for high-beta disruption-free operation. It is designed around a reference plasma with low ripple, good magnetic surfaces, and stability to the important ideal instabilities at beta ~4%. The device size, available heating power, and pulse lengths provide access to a high-beta target plasma state. The NCSX has magnetic flexibility to explore a wide range of equilibrium conditions and has operational flexibility to achieve a wide range of beta and collisionality values. The design provides space to accommodate plasma-facing components for divertor operation and ports for an extensive array of diagnostics.