Radial Plasma Dynamic in Sequential Pinches

• Published in: IEEE transactions on plasma science 2009-11, Vol.37 (11), p.2186-2190
• Main Authors: Kayama, M.E., Clemente, R.A., Honda, R.Y., Dobrowolsky, M.S.
• Format: Article
• Language: English
• Subjects: Density; Electric and magnetic measurements; Electric discharges; Exact sciences and technology; Fluctuations; Gases; Hydrogen; Implosions; Low pressure; Magnetic confinement; Magnetic fields; Magnetic-field measurement; Magnetism; Magnetohydrodynamics; Mathematical models; modeling; Oscillations; Oscillators; Other gas discharges; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma; Plasma confinement; Plasma diagnostic techniques and instrumentation; Plasma dynamics; plasma generation; plasma pinch; Plasma production and heating; Plasma properties; Plasma sources; Plasma temperature; Plasma waves; Probes; Waveforms
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2009.2031868

Plasma dynamic and confinement characteristics were investigated with magnetic probes in a theta pinch operating with oscillatory current waveform and hydrogen gas at pressure between 45 and 150 mtorr. Current-sheath implosion was evident after the third half cycle until sixth half cycle when the external current has practically decayed. Each cycle starts with a trapped reversed magnetic field residual from the previous half cycle. Probe-signal fluctuations due to radial hydromagnetic oscillations were also observed. A modified snowplow model including an initial bias field and a flux-loss term gives a reasonable description of the experimental results for plasma radial dynamic and internal trapped field. Typical equilibrium-density profiles are of a hollow type with maximum density around one-third of the discharge-tube radius. Estimations from these profiles show small variation of temperature and density among half cycles in discharges at low pressure. At high-pressure regime, the temperature strongly drops in subsequent half cycles, while the density increases.