No abstract

An electric propulsion thrust stand capable of supporting testing of thrusters having a total mass of up to 125 kg and producing thrust levels between 100 pN to 1 N has been developed and tested. The design €eatures a conventional hanging pendulum arm attached to a balance mechanism that converts horizontal deflections produced by the operating thruster into amplified vertical motion of a secondary arm. The level of amplification is changed through adjustment of the location of one of the pivot points linking the system. Response of the system depends on the relative magnitudes of the restoring moments applied by the displaced thruster mass and the twisting torsional pivots connecting the members of the balance mechanism. Displacement is measured using a non-contdct, optical linear gap displacement transducer and balance oscillatory motion is attenuated using a passive, eddy-current damper. The thrust stand employs an automated leveling and thermal control system. Pools of liquid gallium are used to deliver power to the thruster without using solid wire conenctions, which can exert undesirablc time-varying forces on the balance. These systems serve to eliminate sources of "zero-drift" that can occur as the stand thermally or mechanically shifts during the course of an experiment. An in-situ calibration rig allows for steady-state calibration before, during and after thruster operation. Thrust mcasuremcnls were carried out on a cylindrical I-Iall thruster that produces mN-level thrust. The measurements were very repeatablc, producing results that coniparc favorably with prcviously published performance data, but with considerably smaller uncertainty.l?4CS numbers:

No abstract

No abstract

No abstract