Negative differential voltage-current characteristics in low-current, low-pressure argon discharges

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

OSTI ID:212819

Phelps, A V ^[1]

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1. Univ. of Colorado, Boulder, CO (United States)

We compare the predictions of various models of negative differential voltage-current characteristics in low-current, low-pressure argon discharges with experiment over a wide range of pressure p and parallel-plane electrode separation d. Mechanisms considered include multi-step ionization processes, such as metastable atom-metastable atom and electron-metastable atom collisional ionization; space charge electric field enhanced processes, such as electron-atom ionization and field dependent ion- and photon-induced emission at the cathode; and thermal processes, such as gas and electrode heating. The discharge current densities considered in this paper are below those required for the onset of constrictions, i.e., in the Townsend or subnormal region. The pd values are 0.15 to 15 Torr cm and the corresponding electric field to gas density ratios E/n are 100 to 4000 Td. The upper limits to the discharge current densities available vary from 5 x 10{sup -8} A/cm{sup 2} at 100 Td to 10{sup -3} A/cm{sup 2} at 4000 Td. A critical feature of all of the data is the linear voltage decrease with increasing current, i.e., the negative differential voltage to current density ratio K is constant. The constancy of this ratio is a crucial test of proposed mechanisms.

• OSTI ID: 212819
• Report Number(s): CONF-950749--
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ARGON
CURRENT DENSITY
GLOW DISCHARGES
IONIZATION