Rotating Field Confinement of Pure Electron Plasmas Using Trivelpiece-Gould Modes

A “rotating wall” electric field is shown to give steady-state confinement of a column of $3\times {10}^9$ electrons in a Penning-Malmberg trap at 4 tesla. By increasing the frequency of the rotating drive, a central-density compression by a factor of 20 has been obtained. For both dipole and quadrupole drives (i.e., $m_{\theta }=1\mathrm{}$ and 2), the compression rate depends on drive frequency, exhibiting peaks associated with $k_z\ne 0$ Trivelpiece-Gould plasma modes. The drive also causes plasma heating, but cyclotron radiation cooling keeps the temperature low enough that background gas ionization is negligible.