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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 21 November 2010, was produced in FY 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program. It reviews propulsion concepts that use plasmas and magnetohydrodynamics. It finds the Ajax MHD energy bypass concept meaningless below Mach 12 but calls a reverse energy bypass with a Virtual Cowl potentially practical. It also predicts that electric propulsion will become standard for spacecraft.
“Jet Propulsion Laboratory”4 pages
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Electromagnetic thrusters use electromagnetic body forces (ExB) of Lorentz
force to accelerate a propellant plasma as shown in Figure 4. 16, 17 The electric
field is applied using electrodes within the thruster. The Lorentz or ExB force
accelerates both positively charged ions and negatively charged electrons or
negative ions in the same direction. The magnetic field can either be applied
externally (applied field thruster) or generated by a very high current (typically
thousands of amps) plasma discharge (self-field thruster). The current also
serves to ionize the propellant. It is the interaction of the electric and magnetic
fields that pushes the plasma out of the thruster at high velocity via the Lorentz
force that acts mutually perpendicular to the electric and magnetic fields.
Spacecraft electromagnetic thrusters are capable of processing much higher
power densities (50 kW to tens of MW) and much higher thrust densities than
electrostatic thrusters (hundreds to thousands of N/m2).
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Figure 4. Electromagnetic Accelerator Field Configuration and Self-Field
Electromagnetic Spacecraft Thrusters. Left: Illustration of the electric and magnetic field
configuration. Center: Photograph of a MW-class pulsed magnetoplasmadynamic {MPD)
thruster being tested at Princeton University. Right: Photograph of a 50-kW steady-state MPD
thruster being tested at Princeton University.
An example of an air-breathing electromagnetic accelerator system for high-
speed and high-altitude flight is shown in Figure 5. Air enters through the inlet
on the left. The center section both accelerates the flow via electromagnetic body
forces and heats the gas through Ohmic heating. The gas is then further
accelerated using a diverging gas-dynamic nozzle.
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.