Session 7RV - Thermal Equilibria and Thermodynamics of Trapped Nonneutral Plasmas.
INVITED session, Thursday morning, November 14
Grand Ballroom, Adam's Mark
\hspace*3exThis paper will discuss three topics: transport of a nonneutral plasma to a state of thermal equilibrium, the thermal equilibrium states themselves, and the longtime evolution of the plasma through a sequence of thermal equilibrium states. Along the way a thermodynamic theory of trapped nonneutral plasmas will be developed. In contrast to neutral plasmas, nonneutral plasmas can be confined by static electric and magnetic fields (e.g., in a Penning trap) and also be in a state of global thermal equilibrium. It is a huge advantage to be able to use the powerful techniques of thermal equilibrium statistical mechanics to describe the plasma state. Such a description is easily obtained, complete (including, for example, the microscopic order for the case of a strongly correlated plasma or crystal), and is in good agreement with experiment. \hspace*3ex A thermodynamic theory of the plasma system yields useful and general results through Maxwell relations and thermodynamic inequalities. Thermal equilibrium plasmas are routinely confined for very long times (days), but are made to evolve through a succession of thermal equilibrium states by the slow addition or subtraction of heat and angular momentum. For example, this can be produced by the application of laser cooling and laser torques. A thermodynamic approach provides a description of this long time transport as two coupled ordinary differential equations for the plasma temperature and rotation frequency. These nonlinear equations can explain the observation of temperature and rotation frequency instabilities and hystersis loops in the long time evolution of the plasmas, and provide a theoretical basis for plasma control. \hspace*3ex Finally, the short time scale collisional transport that brings the plasma to thermal equilibrium in the first place is novel; the transport rate is much more rapid than is predicted by classical theory, where a particle steps by a cyclotron radius following each collision. Theory and experiments suggest that long range interactions (i.e., | r_1 - r_2 | \sim \lambda_D \gg r_c ) can dominate and produce a much enhanced particle and heat flux. [.05in] *Work supported by NSF PHY94-21318, ONR N00014-96-1-0239, and DOE DE-FG03-85ER53199. [.05in]