An oscillator circuit to produce a radio-frequency discharge and   application to metastable helium saturated absorption spectroscopy
  We present an rf gas discharge apparatus which provides an atomic frequency reference for laser manipulation of metastable helium. We discuss the biasing and operation of a Colpitts oscillator in which the discharge coil is part of the oscillator circuit. Radiofrequency radiation is reduced by placing the entire oscillator in a metal enclosure. 
F. Moron, A. L. Hoendervanger, M. Bonneau, Q. Bouton, A. Aspect, D.   Boiron, D. Cl\'ement and C. I. Westbrook
physics.atom-ph