Steady-state confinement of non-neutral plasmas by rotating electric fields

We apply ''rotating wall'' electric fields to spin up a non-neutral plasma in a Penning-Malmberg trap, resulting in steady-state confinement (weeks) of up to 10(9) Mg+ ions. The resulting ion columns can be near global thermal equilibrium, with near-uniform temperature and rotation frequency. The equilibrated plasma E X B rotation rate f(E) is observed to be somewhat less than the drive frequency f(w), with slip Delta f = f(w) - f(E) depending on temperature as Delta f proportional to T-1/2 for 0.05 less than or similar to T less than or similar to 5 eV. Dynamic measurements of applied torque versus slip frequency show plasma spin up and compression for Delta f > 0 and plasma slowing and expansion for Delta f < 0. By gradually increasing f(w), density compression up to 20% of the Brillouin density limit has been achieved. Heating resonances and hysteresis in plasma parameters are also observed.