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Kurt A. Polzin

Bio: Kurt A. Polzin is an academic researcher from Marshall Space Flight Center. The author has contributed to research in topics: Pulsed inductive thruster & Propellant. The author has an hindex of 15, co-authored 147 publications receiving 1053 citations.


Papers
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TL;DR: The use of electric propulsion (EP) on satellites for commercial, defense, and space science missions has been increasing in recent decades, from the first successful operation in 1964 aboard the Zond-2 spacecraft to the present day as mentioned in this paper.

181 citations

Journal ArticleDOI
TL;DR: 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 microN to 1 N has been developed and tested as discussed by the authors.
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 microN to 1 N has been developed and tested. The design features 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-contact, 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 connections, which can exert undesirable 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 measurements were carried out on a cylindrical Hall thruster that produces mN-level thrust. The measurements were very repeatable, producing results that compare favorably with previously published performance data, but with considerably smaller uncertainty.

98 citations

Journal ArticleDOI
TL;DR: In this article, the authors defined magnetic induction as the first ionization potential, and defined the following parameters: B, B = magnetic induction, T C = capacitance, F E = electric field, V=m E0 = initial energy, J e0 = specific energy, S j = current density, A=m _ L = dynamic impedance, H=s LC = coil inductance, H L 0 = initial inductance and H L0 = inductance per unit length.
Abstract: Nomenclature B, B = magnetic induction, T C = capacitance, F E = electric field, V=m E0 = initial energy, J e0 = specific energy, J=kg I = current, A Ibit = impulse bit, N s Isp = specific impulse, s j = current density, A=m _ L = dynamic impedance, H=s LC = coil inductance, H L0 = initial inductance, H L0 = inductance per unit length, H=m L = inductance ratio M = mutual inductance, H; molecular mass, kg mbit = mass bit, kg=pulse mc = critical mass, kg Q1 = first ionization potential, J r = radial coordinate, m Re = external resistance, Rp = plasma resistance, t = time, s ue = exhaust velocity, m=s v = velocity, m=s Vp = plasma voltage, V V0 = initial charge voltage, V z = axial coordinate, m z0 = electromagnetic stroke length, m = dynamic impedance parameter L = inductance change, H = resistivity, m; efficiency, % = nonpropulsive energy fraction A = linear mass density, kg=m = magnetic flux, W 1, 2 = critical resistance ratios

81 citations

Journal ArticleDOI
TL;DR: In this paper, a model of pulsed inductive plasma thrusters consisting of a set of coupled circuit equations and a one-dimensional momentum equation has been non-dimensionalized leading to the identification of several scaling parameters.
Abstract: A model of pulsed inductive plasma thrusters consisting of a set of coupled circuit equations and a one-dimensional momentum equation has been nondimensionalized leading to the identification of several scaling parameters. Contour plots representing thruster performance (exhaust velocity and efficiency) were generated numerically as a function of the scaling parameters. The analysis revealed the benefits of underdamped current waveforms and led to an efficiency maximization criterion that requires the circuit's natural period to be matched to the acceleration timescale. It is also shown that the performance increases as a greater fraction of the propellant is loaded nearer to the inductive acceleration coil

50 citations

Journal ArticleDOI
TL;DR: In this article, the performance of a cylindrical Hall thruster operating at 0 (100 W) input power level was evaluated and the authors reported the measured performance (I(sub sp, thrust and efficiency) of the Hall thrusters.
Abstract: Recent mission studies have shown that a Hall thruster which operates at relatively constant thrust efficiency (45-55%) over a broad power range (300W - 3kW) is enabling for deep space science missions when compared with slate-of-the-art ion thrusters. While conventional (annular) Hall thrusters can operate at high thrust efficiency at kW power levels, it is difficult to construct one that operates over a broad power envelope down to 0 (100 W) while maintaining relatively high efficiency. In this note we report the measured performance (I(sub sp), thrust and efficiency) of a cylindrical Hall thruster operating at 0 (100 W) input power.

44 citations


Cited by
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TL;DR: While the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice), and I believe that the Handbook can be useful in those laboratories.
Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

2,493 citations

Journal ArticleDOI
TL;DR: A short review of electric propulsion technologies for satellites and spacecraft can be found in this paper, where momentum conservation and the ideal rocket equation, specific impulse and thrust, figures of merit and a comparison with chemical propulsion are discussed.
Abstract: This contribution presents a short review of electric propulsion (EP) technologies for satellites and spacecraft. Electric thrusters, also termed ion or plasma thrusters, deliver a low thrust level compared to their chemical counterparts, but they offer significant advantages for in-space propulsion as energy is uncoupled to the propellant, therefore allowing for large energy densities. Although the development of EP goes back to the 1960s, the technology potential has just begun to be fully exploited because of the increase in the available power aboard spacecraft, as demonstrated by the very recent appearance of all-electric communication satellites. This article first describes the fundamentals of EP: momentum conservation and the ideal rocket equation, specific impulse and thrust, figures of merit and a comparison with chemical propulsion. Subsequently, the influence of the power source type and characteristics on the mission profile is discussed. Plasma thrusters are classically grouped into three categories according to the thrust generation process: electrothermal, electrostatic and electromagnetic devices. The three groups, along with the associated plasma discharge and energy transfer mechanisms, are presented via a discussion of long-standing technologies like arcjet thrusters, magnetoplasmadynamic thrusters, pulsed plasma thrusters and ion engines, as well as Hall thrusters and variants. More advanced concepts and new approaches for performance improvement are discussed afterwards: magnetic shielding and wall-less configurations, negative ion thrusters and plasma acceleration with a magnetic nozzle. Finally, various alternative propellant options are analyzed and possible research paths for the near future are examined.

380 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight the most promising developments reported at the 2017 International Workshop on Micropropulsion and Cubesats (MPCS-2017) by leading world-reputed experts in miniaturized space propulsion systems.
Abstract: Rapid evolution of miniaturized, automatic, robotized, function-centered devices has redefined space technology, bringing closer the realization of most ambitious interplanetary missions and intense near-Earth space exploration. Small unmanned satellites and probes are now being launched in hundreds at a time, resurrecting a dream of satellite constellations, i.e., wide, all-covering networks of small satellites capable of forming universal multifunctional, intelligent platforms for global communication, navigation, ubiquitous data mining, Earth observation, and many other functions, which was once doomed by the extraordinary cost of such systems. The ingression of novel nanostructured materials provided a solid base that enabled the advancement of these affordable systems in aspects of power, instrumentation, and communication. However, absence of efficient and reliable thrust systems with the capacity to support precise maneuvering of small satellites and CubeSats over long periods of deployment remains a real stumbling block both for the deployment of large satellite systems and for further exploration of deep space using a new generation of spacecraft. The last few years have seen tremendous global efforts to develop various miniaturized space thrusters, with great success stories. Yet, there are critical challenges that still face the space technology. These have been outlined at an inaugural International Workshop on Micropropulsion and Cubesats, MPCS-2017, a joint effort between Plasma Sources and Application Centre/Space Propulsion Centre (Singapore) and the Micropropulsion and Nanotechnology Lab, the G. Washington University (USA) devoted to miniaturized space propulsion systems, and hosted by CNR-Nanotec—P.Las.M.I. lab in Bari, Italy. This focused review aims to highlight the most promising developments reported at MPCS-2017 by leading world-reputed experts in miniaturized space propulsion systems. Recent advances in several major types of small thrusters including Hall thrusters, ion engines, helicon, and vacuum arc devices are presented, and trends and perspectives are outlined.

225 citations

Journal ArticleDOI
TL;DR: The thrust stand design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust, and incorporates an in situ calibration rig.
Abstract: This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust. The thrust stand position serves as the input to the null-circuit feedback control system and the output is the current to an electromagnetic actuator. Mechanical oscillations are actively damped with an electromagnetic damper. A closed-loop inclination system levels the stand while an active cooling system minimizes thermal effects. The thrust stand incorporates an in situ calibration rig. The thrust of a 3.4 kW Hall thruster is measured for thrust levels up to 230 mN. The uncertainty of the thrust measurements in this experiment is +/-0.6%, determined by examination of the hysteresis, drift of the zero offset and calibration slope variation.

113 citations