J* optimization of small aspect ratio stellarator/tokamak hybrid devices

A new class of low aspect ratio toroidal hybrid stellarators is found using more general plasma confinement optimization criterion than quasi-symmetrization. The plasma current profile and shape of the outer magnetic flux surface are used as control variables to achieve near constancy of the longitudinal invariant J* on internal flux surfaces (quasi-omnigeneity), in addition to a number of other desirable physics target properties. We find that a range of compact (small aspect ratio A), high {beta} (ratio of thermal energy to magnetic field energy), low plasma current devices exist which have significantly improved confinement both for thermal as well as energetic (collisionless) particle components. With reasonable increases in magnetic field and geometric size, such devices can also be scaled to confine 3.5 MeV alpha particle orbits.

[1]  V. Lynch,et al.  Transport Optimization and MHD Stability of a Small Aspect Ratio Toroidal Hybrid Stellarator , 1998 .

[2]  A. Wootton,et al.  EPEIUS: Physics and engineering studies of a small aspect-ratio tokamak-torsatron hybrid , 1997 .

[3]  Harold Weitzner Low collisionality transport in a torus , 1997 .

[4]  John R. Cary,et al.  HELICAL PLASMA CONFINEMENT DEVICES WITH GOOD CONFINEMENT PROPERTIES , 1997 .

[5]  W. A. Cooper Normal curvature, local magnetic shear and parallel current density in tokamaks and torsatrons , 1997 .

[6]  Moroz Spherical Stellarator Configuration. , 1996, Physical review letters.

[7]  Paul Garabedian,et al.  Stellarators with the magnetic symmetry of a tokamak , 1996 .

[8]  James A. Rome,et al.  Orbit topology in conventional stellarators in the presence of electric fields , 1995 .

[9]  David A. Garren,et al.  Existence of quasihelically symmetric stellarators , 1991 .

[10]  N. Dominguez,et al.  Low-aspect-ratio torsatron configurations , 1988 .

[11]  John R. Cary,et al.  Orbits in asymmetric toroidal magnetic fields , 1988 .

[12]  J. Nührenberg,et al.  Quasi-Helically Symmetric Toroidal Stellarators , 1988 .

[13]  James F. Lyon,et al.  Monte Carlo studies of transport in stellarators , 1985 .

[14]  J. C. Whitson,et al.  Steepest‐descent moment method for three‐dimensional magnetohydrodynamic equilibria , 1983 .

[15]  Allen H. Boozer,et al.  Transport and isomorphic equilibria , 1983 .

[16]  Philip E. Gill,et al.  Practical optimization , 1981 .

[17]  Allen H. Boozer,et al.  Guiding center drift equations , 1980 .