Documents / Report
This Defense Intelligence Agency reference document, dated 1 November 2010, is one of a series of advanced technology reports produced in FY 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program. It covers fusion plasma physics, confinement methods, and propulsion concepts that use aneutronic fuels such as hydrogen and boron-11. It concludes that such thrusters may soon replace satellite ion thrusters. It also finds that they will not be practical beyond the solar system without breakthrough propulsion physics.
UNCLASSIFIED//F811. 8FFll!l*L 1!1!11! t!IHL"i' double layer designs, and the VASIMR thruster. Such systems typically have larger specific impulses (up to ~10,000 seconds) but have lower thrust per kW expended. Magnetoplasmadynamic Thrusters The magnetoplasmadynamic (MPD) thruster uses a gaseous fuel that is ionized in one chamber and then fed into an acceleration chamber. Electric and magnetic fields then propel the plasma through the exhaust chamber. The specific impulse and thrust both increase with power input, while the thrust per kW decreases. Exhaust velocities can reach 110,000 m/s, about 20 times greater than liquid rockets. Electrodeless Plasma Thrusters In this design, the plasma is accelerated by magnetized ponderomotive forces, for which nonuniform static magnetic fields and high-frequency electromagnetic fields are applied. The ponderomotive force accelerates positive ions and electrons in the same direction; thus, no dedicated exhaust neutralizer is needed. Since there are no grids and there is no physical contact between the plasma and electrodes, corrosion and spacecraft contamination issues are minimized. Because of the multiple stages involved, the thruster at constant power can also be varied to deliver either higher specific impulse and/or higher thrust. One form of electrodeless thruster is the Pulsed Inductive Thruster (or PIT). A PIT uses perpendicular electric and magnetic fields to accelerate an ionized gas. Capacitors release an approximately 10-μsec pulse of electric current, which generates a radial magnetic field. A circular electrical field is thus induced in the gas, causing ions to travel in the direction opposite that of the original current pulse. Since this motion is perpendicular to the magnetic field, the ions are then accelerated outward to provide thrust. Helicon Double Layer This design introduces gas into a tube (open at one end), which is then converted into a high-density plasma through the use of a helical antenna. Solenoid coils are also used to confine the created plasma. In the case of the helicon double layer, the plasma is then accelerated to supermagnetosonic speeds by traversing an electric double layer, which is created very close to the open end of the tube by a rapidly expanding magnetic field. The European Space Agency (ESA) has tested this design using argon gas and found that the double layer is stable enough to reliably accelerate ions. ESA is currently pursuing this technology for possible use in future missions. VASIMR Thruster The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an electromagnetic thruster for spacecraft propulsion. This design is an electrodeless configuration and operates in three stages. The first stage uses RF helicon antennas to transform the gas into a plasma. The second stage uses an ion cyclotron resonance frequency (again in the radio band) to energize the plasma. The third stage uses electromagnets to create a magnetic nozzle, which converts the thermal energy of the plasma into thrust. Magnetic shielding protects all parts of the VASI MR from direct contact with the contained plasma, mitigating corrosion. The method for heating plasma in VASIMR was originally developed as a result of research into nuclear fusion. With the energy used for RF heating and the amount of propellant delivered for plasma generation, VASIMR is 15 UNCLASSIFIED/ )F8A 8FFI&I.«1k Wfi&i a••k>/
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 36 pages are in the text index: search them above, or from the library's search.