An electrothermal thruster that operates in a rapid-pulse mode at low power ( 85%of the initial stored energy is transferred to the arc in a unipolar pulse. The arc discharges occur in a cylindrical capillary upstream of a converging–diverging nozzle, and all of the energy additionoccurs in the subsonic region. Tests with heliumpropellant are conducted for two 20-deghalf-angle conicalnozzleswith area ratiosof 20 and230.Thrust levels from14 to 31mNaremeasured,andamaximumspeci c impulse of 313 s is achieved with 36% ef ciency at 119 W. A time-dependent, quasi-one-dimensional numerical model is developed to evaluate energy losses using a time-marching procedure, and comparisonwith experimental results is good. Heat transfer losses to the wall in the subsonic region are found to be the primary energy-loss mechanisms. Speci c impulse is strongly affected by wall temperature. Viscous effects become important as the speci c energy increases above 12 MJ/kg and the throat Reynolds number falls below 1 £ 103.
[1]
T. Peters.
Über den Zusammenhang des Steenbeckschen Minimumprinzips mit dem thermodynamischen Prinzip der minimalen Entropieerzeugung
,
1956
.
[2]
R. Burton,et al.
Experiments on a repetitively pulsed electrothermal thruster
,
1987
.
[3]
Francis M. Curran,et al.
An extended life and performance test of a low-power arcjet
,
1988
.
[4]
J. Anderson,et al.
A Time-Dependent Analysis for Vibrational and Chemical Nonequilibrium Nozzle Flows
,
1969
.
[5]
M. Kristiansen,et al.
The pulsed discharge arc resistance and its functional behavior
,
1989
.
[6]
R. Welle.
Space propulsion applications of helium arcjets
,
1997
.
[7]
William B. Maier,et al.
A lumped circuit model for transient arc discharges
,
1988
.
[8]
R. Burton,et al.
Energy-mass coupling in high-pressure liquid-injected arcs
,
1991
.
[9]
A. Kadish,et al.
Comparison of the AWA lumped-circuit model of electrical discharges with empirical data
,
1990
.