ORBIT SQUEEZING IN A MAGNETIC WELL

It is shown that the size of a charged particle's drift orbit is squee zed, i.e., reduced, in a magnetic well in tokamak plasmas. The squeezi ng factor depends on the energy of the particle, being larger for high er-energy particles. Therefore, for high-energy particles, the size of the drift orbit depends only on the magnetic geometry. These energy-i ndependent drift orbits are also observed [J.A. Rome and Y.-K. M. Ping , Nucl. Fusion 19, 1193 (1979)]. The implications on the core confinem ent improvement physics and the confinement of the advanced fuel are d iscussed. (C) 1996 American Institute of Physics.