Pulsed thrust measurements using laser interferometry

Cubbin, E. A.; Ziemer, John; Choueiri, Edgar Y.; Jahn, R. G.

doi:10.1063/1.1148116

Cited by 78 publications

(33 citation statements)

References 9 publications

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“…There are two thrust measurement systems typically used for the characterization of electric propulsion technologies: the torsion balance and pendulum thrust stand. The torsion balance is used routinely to determine the thrust produced by pulsed discharges [1][2][3] and has also been used for steady state systems. 4,5 Its mechanical structure allows a rapid response to an applied impulse and thrusts of the order of nano Newtons have been measured to ±2% error; 6 however, a damping system is required which adds to the system complexity.…”

Section: Introductionmentioning

confidence: 99%

Impact of plasma noise on a direct thrust measurement system

Pottinger

Lamprou

Knoll

et al. 2012

Review of Scientific Instruments

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In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.

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Section: Introductionmentioning

confidence: 99%

Impact of plasma noise on a direct thrust measurement system

Pottinger

Lamprou

Knoll

et al. 2012

Review of Scientific Instruments

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“…It is worth mentioning that, for the same discharge voltage, coil currents and propellant flows, values of the discharge current measured at the EPPDL vacuum facility 13 were generally about 10% lower than those measured at the PPPL Small Hall Thruster facility. This apparently was due to the fact that the operating background pressure of Xe (about 1×10 -5 Torr for the total propellant flow rate of 0.8 mg/s) was typically 5-7 times lower than that at the PPPL facility.…”

Section: Methodsmentioning

confidence: 99%

“…The EPPDL thrust stand 13 was designed to measure accurately impulse bits for pulsed plasma thrusters (PPTs) within the range of 10 -4 -10…”

Section: Methodsmentioning

confidence: 99%

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Parametric investigation of miniaturized cylindrical and annular Hall thrusters

Smirnov¹,

Raitses²,

Fisch³

2002

Journal of Applied Physics

118

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Conventional annular Hall thrusters become inefficient when scaled to low power. An alternative approach, a 2.6-cm miniaturized cylindrical Hall thruster with a cusp-type magnetic field distribution, was developed and studied. Its performance was compared to that of a conventional annular thruster of the same dimensions. The cylindrical thruster exhibits discharge characteristics similar to those of the annular thruster, but it has a much higher propellant ionization efficiency. Significantly, a large fraction of multicharged xenon ions might be present in the outgoing ion flux generated by the cylindrical thruster. The operation of the cylindrical thruster is quieter than that of the annular thruster. The characteristic peak in the discharge current fluctuation spectrum at 50-60 kHz appears to be due to ionization instabilities. In the power range 50-300 W, the cylindrical and annular thrusters have comparable efficiencies (15-32%) and thrusts (2.5-12 mN). For the annular configuration, a voltage less than 200 V was not sufficient to sustain the discharge at low propellant flow rates. The cylindrical thruster can operate at voltages lower than 200V, which suggests that a cylindrical thruster can be designed to operate at even smaller power. * Electronic mail: asmirnov@pppl.gov 2

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“…[1][2][3] Generally, the impulse generated by a device is investigated by measuring the maximum deflection of the balance caused by a given impulse. [2,3] There are two major shortcomings of this approach.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Time-Dependent Forces on a Nano-Newton-Second Impulse Balance

D’Souza¹,

Ketsdever²

2004

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A torsional impulse balance has been developed as a new diagnostic tool to study fundamental physical processes in micropropulsion systems and laser-surface interactions. The impulse balance has been designed and tested with a robust calibration system to measure impulsive forces with resolution as low as several nano-Newton-seconds. The behavior of the impulse balance was thoroughly studied and characterized. A simple analytical model of the balance's motion was developed from the general equation of motion of an underdamped, harmonically oscillating system. Also, two distinct methods of analyzing the experimental data from the nanoimpulse balance have been investigated. The first method resolves the total impulse as a function of the balance's maximum deflection. The second method enables the determination of the impulse and/or force applied as a function of time from the balance's time-resolved motion.A calibration scheme employing electrostatic actuation techniques is used to experimentally validate the model and impulse measurement techniques. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

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Pulsed thrust measurements using laser interferometry

Cited by 78 publications

References 9 publications

Impact of plasma noise on a direct thrust measurement system

Impact of plasma noise on a direct thrust measurement system

Parametric investigation of miniaturized cylindrical and annular Hall thrusters

Investigation of Time-Dependent Forces on a Nano-Newton-Second Impulse Balance

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