Steady-State Confinement of Non-Neutral Plasmas Using Trivelpiece-Gould Modes Excited by a ''Rotating Wall''

Conference · Fri Dec 31 04:00:00 EST 1999

OSTI ID:783890

Anderegg, F; Hollmann, E M; Driscoll, C F

A ''rotating wall'' voltage varying as exp(im{sub {theta}}{theta}+ ik{sub z}z - i2{pi}ft) can give steady-state confinement of more than 10{sup 9} charges in a Penning-Malmberg trap at 4 Tesla. For both pure ion plasmas and pure electron plasmas, the torque exerted on the plasma by the rotating wall exhibits peaks at the frequencies of k{sub z} {ne} 0 Trivelpiece-Gould modes. As expected, modes with f > m{sub {theta}}fr (i.e. propagating faster than the plasma rotation) give positive torque and cause plasma compression; and modes with f < m{sub {theta}}fr give adverse torque and cause plasma expansion. The rotating wall drive also causes plasma heating, but cyclotron radiation (in the electron case) and collisions with background residual neutral gas (in the ion case) keep the temperature low enough that background ionization is negligible. The rotating wall ''slip'' is typically greater for electrons than for ions, because f - m{sub {theta}}fr is proportional to the plasma frequency {omega}{sub p}. This contrasts with the k{sub z} = 0 rotating wall perturbation which couples to crystallized ion plasmas with no slip. By increasing the frequency of the rotating wall, we observed a plasma central density compression of about a factor of 20. These techniques may be useful for a variety of trapping experiments.

• Research Organization: Department of Physics and Institute for Pure and Applied Physical Sciences; University of California at San Diego, La Jolla, CA (US)
• Sponsoring Organization: none (US)
• OSTI ID: 783890
• Report Number(s): none; ISBN 1-56396-913-0; ISSN 0094-243X; CODEN APCPCS; ISBN 1-56396-913-0; ISSN 0094-243X; CODEN APCPCS
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
COMPRESSION
CYCLOTRON RADIATION
ELECTRIC FIELDS
IONIZATION
LANGMUIR FREQUENCY
PLASMA CONFINEMENT
PLASMA EXPANSION
PLASMA HEATING
ROTATING PLASMA
ROTATION
SLIP
STEADY-STATE CONDITIONS
TRAPS