Spatiotemporal profile of emission from oscillating dc micro discharges
  The axial light distributions in parallel-plate dc microdischarges in argon show similar behavior to large scale discharges. Between the low-current Townsend mode and the high current glow mode exists a large region of currents where different oscillations appear and the dynamic Volt-Ampere characteristic shows hysteresis behavior. During the oscillations the maximum peak intensity moves closer to the cathode, which is characteristic for the abnormal glow regime even though the average current is considerably smaller. 
T. Kuschel, N. \v{S}koro, D. Mari\'c, I. Stefanovi\'c, G. Malovi\'c,   J. Winter, and Z. Lj. Petrovi\'c
physics.plasm-ph