The next stage in the tuberculosis movement: A criticism and a suggestion

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Modeling the plasma plume of a hollow cathode

In this study, a numerical model is developed to simulate the xenon plasma plume from a thermionic hollow cathode employing an orifice plate used for propellant ionization and beam neutralization in an electrostatic space propulsion system. The model uses a detailed fluid model to describe the electrons and a particle-based kinetic approach is used to model the heavy xenon ions and atoms. A number of key assumptions in terms of physical modeling and boundary conditions of the simulations are assessed through direct comparisons with experimental measurements. For two of the three cathode operating conditions considered, good agreement with the measured data is obtained. The third condition appears to lie in a different physical regime where elevated electron and ion temperatures and decreased transport coefficients are required in the simulation to provide agreement between the model and the measured data. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71113/2/JAPIAU-95-7-3285-1.pd

The T6 Hollow Cathode: Measurements and Modeling

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76762/1/AIAA-2003-4171-765.pd

Grid erosion analysis of the T5 ion thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76419/1/AIAA-2001-3781-901.pd

Plume measurement and modeling results for a hollow cathode micro-thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77184/1/AIAA-2001-3795-876.pd

Annular Engine Development Status

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106479/1/AIAA2013-3892.pd

Development Status of High-Thrust Density Electrostatic Engines

Ion thruster technology offers the highest performance and efficiency of any mature electric propulsion thruster. It has by far the highest demonstrated total impulse of any technology option, demonstrated at input power levels appropriate for primary propulsion. It has also been successfully implemented for primary propulsion in both geocentric and heliocentric environments, with excellent ground/in-space correlation of both its performance and life. Based on these attributes there is compelling reasoning to continue the development of this technology: it is a leading candidate for high power applications; and it provides risk reduction for as-yet unproven alternatives. As such it is important that the operational limitations of ion thruster technology be critically examined and in particular for its application to primary propulsion its capabilities relative to thrust the density and thrust-to-power ratio be understood. This publication briefly addresses some of the considerations relative to achieving high thrust density and maximizing thrust-to-power ratio with ion thruster technology, and discusses the status of development work in this area being executed under a collaborative effort among NASA Glenn Research Center, the Aerospace Corporation, and the University of Michigan

High Thrust-to-Power Annular Engine Technology

Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan

Thrust Stand Characterization of the NASA Evolutionary Xenon Thruster (NEXT)

Direct thrust measurements have been made on the NASA Evolutionary Xenon Thruster (NEXT) ion engine using a standard pendulum style thrust stand constructed specifically for this application. Values have been obtained for the full 40-level throttle table, as well as for a few off-nominal operating conditions. Measurements differ from the nominal NASA throttle table 10 (TT10) values by 3.1 percent at most, while at 30 throttle levels (TLs) the difference is less than 2.0 percent. When measurements are compared to TT10 values that have been corrected using ion beam current density and charge state data obtained at The Aerospace Corporation, they differ by 1.2 percent at most, and by 1.0 percent or less at 37 TLs. Thrust correction factors calculated from direct thrust measurements and from The Aerospace Corporation s plume data agree to within measurement error for all but one TL. Thrust due to cold flow and "discharge only" operation has been measured, and analytical expressions are presented which accurately predict thrust based on thermal thrust generation mechanisms