Performance of a 15-centimeter diameter, hollow-cathode Kaufman thrustor

9th Electric Propulsion Conference

1972

Self Cite

Thruster performance and stability over a range of beam currents is a function of the hollow cathode propellant flow which depends in part on the baffle geometry. Variable magnetic baffles have been used to allow a change in baffle geometry to Improve thruster performance and stability. Test results of a 30-cm thruster with magnetic baffle are presented. Thruster performance characteristics are analyzed to show how the magnetic baffle field strength can improve performance at a fixed beam current, as well as increase the range of ion beam current for throttling.

Section: Resultsmentioning

confidence: 99%

A 30-cm diameter bombardment thruster with a variable magnetic baffle

9th Electric Propulsion Conference

1972

Self Cite

“…The hollow cathode has demonstrated lifetimes of more than 2000 hr, 5 with projected lifetimes of 10,000 hr. The capability of pretesting a flight-type hollow cathode and the low cathode power requirements are distinct advantages compared to the oxide magazine cathode.…”

Section: Fig 3 Locations Of Ta Ribbon Cathodes (Edge Views) Tested Imentioning

confidence: 99%

“…This dimension was reduced from 6.35-to 3.8-cm diam. A comparison of an oxide magazine cathode thruster and a hollow cathode thruster (with a reduced diameter pole piece) as described by Bechtel et al 5 is shown in Fig. 11.…”

Section: Fig 3 Locations Of Ta Ribbon Cathodes (Edge Views) Tested Imentioning

confidence: 99%

Discharge chamber optimization of the Sert II thruster.

Journal of Spacecraft and Rockets

1968

An experimental investigation was conducted to determine the optimum discharge chamber configuration of a 15-cm-diam, mercury-bombardment thruster for the SERT (Space Electric Rocket Test) II mission. The experimental thruster used a thermionic, oxide magazine cathode and permanent magnets. A systematic variation of the magnetic field shape and strength, propellant introduction mode, and ion extraction system determined the final configuration which provided thruster operation at 0.25 amp beam current and 3000 v net accelerating potential at propellant utilization efficiencies in excess of 90% for some operating conditions. Discharge chamber energy losses were 205 ev per beam ion, excluding cathode power, at a propellant utilization efficiency of 85%. A change from an oxide magazine to a hollow cathode in the present SERT II thruster caused a change in only one of the parameters optimized in this, investigation.

“…Such thruster operation is characteristically accompanied by poor thruster performance. 3 Operation at AF/ > 32 v was possible only by reducing the total propellant flow to far less than a scaled value. Although the performance at reduced propellant flows was the best for this thruster configuration, it still falls well below the 15-cm thruster performance in both propellant utilization efficiency t]u and discharge losses e/.…”

Section: Direct Scaling Effects and L/dmentioning

confidence: 99%

“…3 All dimensions of the discharge chamber were doubled with the exception of the screen pole piece, which was unchanged. The previously described two-grid system was used.…”

Section: Direct Scaling Effects and L/dmentioning

confidence: 99%

Performance and control of a 30-cm-diam, low-impulse, Kaufman thruster

Journal of Spacecraft and Rockets

1970

An experimental investigation was conducted to develop a 30-cm-diam, mercury bombardment thruster for potential space applications. Thruster operating efficiencies were improved by variation of the discharge-chamber geometry and magnetic field shape. A single, glass-coated system was used to achieve efficient thruster operation at lower specific impulse than previous bombardment thrusters. Propellant utilization efficiencies greater than 90% and discharge losses less than 200 ev/ion were attained. Estimated over-all thruster efficiency was about 58% at a specific impulse of 2200 sec. The investigation included a control system that afforded enough flexibility to throttle the ion beam current over a range of 2 to 1. This was accomplished without compromising expected lifetime of thruster components. NomenclatureA 0 -annular open area between distribution pole piece and baffle, cm 2 d = diameter, cm / sp = specific impulse, sec J = neutral propellant flow, equivalent amp L/D = thruster-length/anode-diameter ratio I = length, cm AV = potential voltage, v 7] = efficiency e = energy loss per beam ion, ev/ion Subscripts B = baffle / = discharge chamber OK,OM,OT = cathode, main, and total (flow), respectively P = distributor pole piece p = power (efficiency) SC = screen collar T = total U -propellant utilization