Studies of an inductively coupled plasma

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:213007

Annaratone, B M; Chen, B H; Allen, J E ^[1]

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1. Univ. of Oxford (United Kingdom)

The high plasma density of inductive plasmas has recently become utilised in numerous applications. These include the production of plasma for material processing, ion sources, creation of atomic gases and fighting. Characteristics typical of inductive plasmas are certainly present in commercial flat coil systems but are much more evident in the ordinary inductive coil. Here the currents induced in the plasma can determine the formation of a partially or fully developed H regime. In this experiment the plasma was obtained in a {Phi} = 38mm tube around which a 7 turns, 70mm coil was wrapped. The coil was fed with a 13.56 MHz current supplied by an RF generator in matched conditions. The power was increased up to 300W while the pressure of the argon in the tube was varied from 10{sup -3}1Torr. The range of parameters for the existence of the E and H regime is shown. Here the transition lines were obtained by scanning in RF voltage at constant pressure. The voltage was first increased going through the breakdown of an E discharge. Increasing further the voltage the H discharge appeared with a weak E discharge outside the coil. This transition showed a gradual change in the low pressure range but was very sudden for pressures above 10{sup -1} Torr. Decreasing the voltage the closed current induced in the H discharge produces a hysteresis and the H discharge is maintained for very low power. In fig. 1 the voltage before each transition is reported to represent the condition that caused the transition. For example in the E to H transition at constant power the voltage decreases suddenly as in a transformer where the secondary is suddenly closed.

• OSTI ID: 213007
• Report Number(s): CONF-950749--
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
66 PHYSICS
DISTRIBUTION FUNCTIONS
ELECTRON DENSITY
ELECTRON TEMPERATURE
INDUCTION
ION SOURCES
MEASURING METHODS
PLASMA
PLASMA DENSITY
PLASMA PRODUCTION