Radial compression and inward transport of positron plasmas using a rotating electric field

It has recently been demonstrated that positron plasmas confined in a Penni ng-Malmberg trap can be compressed radially by applying a rotating electric field [Phys. Rev. Lett. 85, 1883 (2000)]. A more complete description of t he original experiments is presented, together with the results of new meas urements. Good coupling of the rotating electric field is observed over a b road range of frequencies. The heating caused by the rotating field is coun teracted by cooling using a polyatomic gas. Rapid compression rates n/n sim ilar to 15 s(-1) can be achieved, with central density increases of a facto r of 20 or more. The good coupling and high compression rates can be explai ned in terms of excitation of heavily damped Trivelpiece-Gould modes, or al ternatively as coupling directly to particle bounce resonances. Potential i mprovements and applications are discussed, including the production of hig h-density positron plasmas and brightness-enhanced positron beams. (C) 2001 American Institute of Physics.