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This Defense Intelligence Agency reference document, dated 10 March 2010, covers inertial electrostatic confinement (IEC) fusion. It was produced in FY 2009 under the DIA's Advanced Aerospace Weapon System Applications (AAWSA) program. The report focuses on work at the University of Illinois Urbana-Champaign and reviews IEC basics, experiments, theory and applications such as neutron sources, explosives detection and space propulsion. It concludes by proposing a breakeven experiment for p-11B fusion that uses a hydrogen plasma simulation.
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UNCLASSIFIED/ ,<F9A: 9FFI~l.11k WE&i 9Hllf Section I. IEC Background and Basics Before considering detail, it is helpful to obtain a rough idea of how inertial electrostatic confinement (IEC) fusion works. Gas ~ccd I in~ Spherical Vacuum . Chamber !!1~h-\'olta~c FeeJlhrough H,gh-Voltagc Power Suppl} To Vacuu ""·' Figure 1.1. An UIUC Spherical IEC. The plasma discharge between the grid and vacuum wall creates an ion source that is extracted and directed towards the center by the highly charged negative grid. A photograph of a typical !EC chamber is shown in the center. A photograph of the discharge through the view port shows the "Star Mode" discharge where ion beams are created that pass through the grid openings. This is important for long run times since 10n bombardment of the grids, hence grid wire sputtering, is m1nim1zed. For this purpose the experimental IEC device of Figure 1.1 is considered. As shown, this "gridded" type IEC has a spherical mesh grid suspended on a high voltage feed-through in the center of a metal vacuum vessel. The fusion "fuel", e.g. deuterium gas, is first fed into the chamber originally prepared at high vacuum, e.g. 10- 7 Torr. The fuel gas brings the pressure up into the 10's of Torr region. Then the voltage on the grid is raised into the many (-) kV range, creating a plasma discharge between the high voltage grid and chamber wall (electrically grounded). The high negative voltage on the grid serves to extract the ion from the plasma, accelerating them towards the center of the grid where in principle they interact and fuse. In practice however, the scattering cross section is larger than the fusion cross section. Thus many ions scatter without reacting (fusing). Many "near misses" essentially pass straight through the center of the plasma core and exit. This dominance of scattering over fusion reactions is the central issue of all fusion confinement approaches, forcing use of strong confinement so the ions have many passes and hence a good probability of fusing before being lost from the fusion reaction chamber. In the IEC multiple passes occur because the ions are trapped in a potential "well" created by the buildup of positive charge due to the large flow of the accelerated ions into a small "core" region in the center of the negative grid. Viewed in another way, the ions extracted from the region between the grid and the wall can scatter and pass back through the grid, but can only return to the same potential surface they were born on. Thus they cannot reach the vessel wall, but instead lose their kinetic energy, stop, and are accelerated by the grid potential back into the center of the grid. This then provides many "recirculations" through the center of the grid volume where they have a finite probability of fusing. If not for the existence 1 UNCLASSIFIED/ ,sralil 8FFI&lallb 1!181! ·••LY
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 72 pages are in the text index: search them above, or from the library's search.