Electron heating mode transitions in a low pressure capacitively coupled oxygen discharge

• Using particle-in-cell Monte Carlo collision simulations we have demonstrated an electron heating mode transition from drift-ambipolar (DA) mode to α-mode in the capacitively coupled oxygen discharge as the operating pressure and/or electrode separation are increased. Here we explore further the transition as pressure and electrode separation are varied. At fixed electrode spacing of 45 mm when operating at low pressure (10 mTorr) the electron heating is a combination of DA- and α-mode heating while at higher pressures (>30 mTorr) electron heating in the sheath regions dominates. When varying the electrode spacing from 25 to 60 mm at fixed operating pressure at the higher pressures (50 mTorr) the electron heating is a combination of DA- and α-mode heating for small electrode spacing and it transitions to pure α-mode heating as the electrode spacing is increased. We relate the transition to increased electronegativity and generation of drift and ambipolar electric field within the electronegative core when the discharge pressure is low or electrode spacing is small.

Subject headings

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Keyword

cpacitively coupled discharge

detachment

electron heating

oxygen

particle-in-cell Monte Carlo collision

Chemical bonds

Electrodes

Electronegativity

Electrons

Monte Carlo methods

Plasma heating

Ambipolar electric fields

Capacitively coupled

Discharge pressures

Electrode separation

Monte Carlo collision

Operating pressure

Electric discharges

Publication and Content Type

ref (subject category)

art (subject category)