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.
UNCLASSIFIEL,fl"e" Cl"l"!e1,it tl!!L CHE I The perennial challenge for developing such a device into a power reactor is the feat of manufacturing and compressing 10 such 1-mm DT fuel pellets per second. One significant problem is maintaining equal pressure on the pellets repeatedly to permit energy production. ELECTROSTATIC CONFINEMENT This simple method of confinement is composed of concentric spheres (or sometimes cylinders) acting as anode and cathode in a vacuum known as a Farnsworth-Hirsch Fusor or, more commonly, Inertial Electrostatic Confinement (IEC). As shown in Figure 5, the inner sphere (cathode) is not solid, but rather is composed of a wire grid. Ions entering the vacuum chamber between the anode and cathode are accelerated through a large potential difference toward the cathode. Passing through the cathode, the ions collide in the central region, with a small portion of the plasma population undergoing fusion. 1• 2, 3 However, using this simple setup, it has been argued that net energy production is not viable for anything other than deuterium-tritium fusion, in part because the fusion-collision cross section is several orders of magnitude smaller than the Coulomb-collision cross section. 4 An additional difficulty is that some of the plasma interacts directly with the cathode, contaminating the plasma with heavy sputtered ions. A method for mitigating this problem is to eliminate the cathode grid and instead use magnetic (and electrostatic) fields to create a virtual cathode composed of electrons. Such devices include the Polywell 5 and the Penning trap. 6 One such Penning trap design developed at Los Alamos injects electrons into the central region in such a manner as to produce a harmonic oscillator potential. Called a Periodically Oscillating Plasma Sphere (POPS), ions in this chamber then also undergo harmonic oscillations and can become phase-locked with the use of an externally applied radiofrequency electric field. 7, 8 This allows the ions to reach very high densities and temperatures as they collide at the center of the chamber. This promising design eliminates any power loss due to Coulomb collisions and substantially increases the efficiency of fusion-power generation. '·';.;' ,. ':-..,;,;,;,;,'-:. ',_'-" ''' '< '' ' ...~''::......z.:•,''"-"• ' 'IEC Fusor'i ,,-; ...',_,;,;,',_',_).'''2- , ' '' ~',,','''-"''-,'-..:. Figure S. IEC Fusor and Polywell Confinement Configurations UNCLASSIFIED/ /P:SR: err1e1111t ~!H! :SHLY 8
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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.