Density enhancement of an RF plasma in a magnetic quadrupole

A new method for the effective confinement of a low pressure gas discharge has been proposed by Christiansen and Jacoby. The principal component is a magnetic quadrupole superimposed upon an RF-driven gas discharge plasma. It has been suggested to use the device as an ion source for accelerator applications and as a plasma target to investigate the interaction of heavy ion beams with a magnetically confined plasma. A complete experiment including a capacitively coupled radio frequency (CCRF) discharge and an electric quadrupole magnet was set up and investigated by applying spectroscopic diagnostic methods. The plasma parameters for the magnetically confined CCRF discharge were measured using a Ar : He gas mixture. The electron temperature and the electron density as a function of the gas pressure and the magnetic field could be determined. A maximum of the mean electron temperature was identified as due to collisionless heating. Further, an ion beam was extracted and the mean electron density derived. The confinement of the plasma at low pressures between 0.4 and 1 Pa has also been obtained with an electron density of 3 x 10(17) m(-3).