Colloid Micro-Newton Thrusters for the space technology 7 mission

Ziemer, John; Randolph, Thomas; Franklin, G.; Hruby, Vlad; Spence, Douglas; Demmons, Nathaniel; Roy, Thomas; Ehrbar, Eric; Martin, Roy; Connolly, William

doi:10.1109/aero.2010.5446760

Cited by 33 publications

(17 citation statements)

References 10 publications

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“…The low absolute thrusts (≈ 10's of μN ) yet relatively high system masses [18] of electrospray thrusters can present challenges when attempting to obtain Direct Thrust Measurements (DTM) using a dedicated balance or other force transducer, leading to few examples in the literature. In Ref.…”

Section: Introductionmentioning

confidence: 99%

Comparing Direct and Indirect Thrust Measurements from Passively Fed Ionic Electrospray Thrusters

Courtney

Dandavino

Shea

2016

Journal of Propulsion and Power

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Highly ionic beams of several hundred μA per cm 2 have been measured from porous glass ionic liquid electrospray sources fabricated using a conventional mill. The thrust output from three prototype devices, two emitting the ionic liquid EMI-Im and one emitting EMI-BF 4, was measured directly using a precise balance. Thrusts up to 50 μN were measured when emitting EMI-Im in a bipolar, alternating potential configuration at less than 0.8 W input power and with propellant supplied from an internal reservoir. Measurements of mass spectra via Time of Flight spectrometry, angle resolved current distributions, ion fragmentation and energy deficits have been applied to accurately calculate thrust and mass flow rates indirectly from the same devices. For two of three cases, calculated and directly measured thrusts were in agreement to within a few μN at input powers from 0.1 W to 0.8 W . Emissions of EMI-BF4 are shown to yield nearly purely ionic beams supporting high propulsive efficiencies and specific impulses, ∼ 65 % and > 3200 s respectively at 0.5 W . Conversely, greater polydispersity was observed in EMI-Im emissions, contributing to reduced specific performance, ∼ 50 % propulsive efficiency and ∼ 1500 s specific impulse at 0.5 W .

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Section: Introductionmentioning

confidence: 99%

Comparing Direct and Indirect Thrust Measurements from Passively Fed Ionic Electrospray Thrusters

Courtney

Dandavino

Shea

2016

Journal of Propulsion and Power

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“…The gate signal, pulsated at the reference frequency, f ref , between 0 V and V gate = 3000 V or −3000 V depending on emission polarity, is generated using a high voltage pulse generator (DEI model PVX-4140) controlled by a signal generator, and the same control signal is used as reference input for the lock-in amplifier. The noise-floor of the thrust-stand output is typically around 10 included in Eq. (2) to take into account the transparency of the three-electrode assembly between the emitter and the plate.…”

Section: Thrust Measurement From An Electrospray Devicementioning

confidence: 99%

“…1,2 Several miniature thruster technologies, such as, cold-gas thrusters, 1,3 electrospray propulsion using liquid metals 4 or ionic liquids, [5][6][7][8][9][10][11] micro resisojets, 12,13 and micro pulsed plasma thrusters 13 are under investigation as prospective candidates targeting stable thrusts in the range of a few µN to several hundred µN. Several thrust-stands have been reported over the last few years for measuring thrust from these microthrusters with sub-µN resolutions.…”

Section: Introductionmentioning

confidence: 99%

A 10 nN resolution thrust-stand for micro-propulsion devices

Chakraborty

Courtney

Shea

2015

Review of Scientific Instruments

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We report on the development of a nano-Newton thrust-stand that can measure up to 100 µN thrust from different types of microthrusters with 10 nN resolution. The compact thrust-stand measures the impingement force of the particles emitted from a microthruster onto a suspended plate of size 45 mm × 45 mm and with a natural frequency over 50 Hz. Using a homodyne (lock-in) readout provides strong immunity to facility vibrations, which historically has been a major challenge for nano-Newton thrust-stands. A cold-gas thruster generating up to 50 µN thrust in air was first used to validate the thrust-stand. Better than 10 nN resolution and a minimum detectable thrust of 10 nN were achieved. Thrust from a miniature electrospray propulsion system generating up to 3 µN of thrust was measured with our thrust-stand in vacuum, and the thrust was compared with that computed from beam diagnostics, obtaining agreement within 50 nN to 150 nN. The 10 nN resolution obtained from this thrust-stand matches that from state-of-the-art nano-Newton thrust-stands, which measure thrust directly from the thruster by mounting it on a moving arm (but whose natural frequency is well below 1 Hz). The thrust-stand is the first of its kind to demonstrate less than 3 µN resolution by measuring the impingement force, making it capable of measuring thrust from different types of microthrusters, with the potential of easy upscaling for thrust measurement at much higher levels, simply by replacing the force sensor with other force sensors. C 2015 AIP Publishing LLC. [http://dx

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“…(2) Similarly, again referring to the situation shown in Figure 1, nonzero currents, IY or Iz , yield magnet dipole components that are orthogonal to the magnetic field and produce torque. Following the same argument as for the force and assuming that oscillatory torques can be ignored, the net torque is given by (3) So by controlling the currents in the three coils of the smaller structure one force component and two torque components can be varied, allowing partial positioning and orientation of these two entities relative to each other. (It should be recalled that for any force or torque felt by the smaller structure there is an opposite force or torque felt by the larger structure).…”

Section: F' =Ax {Ixnab(x)cos(2nf T)cos(2nf T+(/j))mentioning

confidence: 99%

“…Several proposals have been suggested for determining the location of the satellites, but the more difficult problem is developing a system that can hold the satellites at those desired locations and orientations. The two most common "solutions" are to use micro-thrusters [3], though these require propellant and will eventually be depleted, or to choose orbital patterns that minimize relative perturbations [4,5], but for highly precise positioning this is not adequate. Neither of these approaches solves the problem for long duration missions such as a multi-element telescope where the mirrors must be located and oriented to a tolerance less than an optical wavelength.…”

Section: Introductionmentioning

confidence: 99%

Alternating magnetic field forces for satellite formation flying

2013

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address: Mark.A.Nurge@nasa.gov Selected future space missions, such as large aperture telescopes and multi-component interferometers, will require the precise positioning of a number of isolated satellites, yet many of the suggested approaches for providing satellites positioning forces have serious limitations. In this paper we propose a new approach, capable of providing both position and orientation forces, that resolves or alleviates many of these problems. We show that by using alternating fields and currents that finely-controlled forces can be induced on the satellites, which can be individually selected through frequency allocation. We also show, through analysis and experiment, that near field operation is feasible and can provide sufficient force and the necessary degrees of freedom to accurately position and orient small satellites relative to one another. In particular, the case of a telescope with a large number of free mirrors is developed to provide an example of the concept. We. also discuss the far field extension of this concept.

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Colloid Micro-Newton Thrusters for the space technology 7 mission

Cited by 33 publications

References 10 publications

Comparing Direct and Indirect Thrust Measurements from Passively Fed Ionic Electrospray Thrusters

Comparing Direct and Indirect Thrust Measurements from Passively Fed Ionic Electrospray Thrusters

A 10 nN resolution thrust-stand for micro-propulsion devices

Alternating magnetic field forces for satellite formation flying

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