Polywell

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File:Polywell WB-6 complete.jpg
WB-6, assembled

The polywell is a plasma confinement concept that combines elements of inertial electrostatic confinement and magnetic confinement fusion, intended ultimately to produce fusion power. The name polywell is a portmanteau of "polyhedron" and "potential well."

The polywell consists of electromagnet coils arranged in a polyhedral configuration and positively charged to between several 10s and low 100s of kilovolts. This charged magnetic polyhedron is called a MaGrid. Electrons are introduced outside the "quasi-spherical" MaGrid and are accelerated into the MaGrid due to the electric field. Within the MaGrid, magnetic fields confine most of the electrons and those that escape are retained by the electric field. This configuration traps the electrons in the middle of the device focusing them near the center which produces a virtual cathode (negative electric potential). The virtual cathode is used to accelerate and confine the ions to be fused which, except for minimal losses, never reach the physical structure of the MaGrid. It was developed by Robert Bussard under a US Navy research contract as an improvement of the Elmore-Tuck-Watson fusor which is an inverted potential Farnsworth-Hirsch fusor.

Design

Problems with Farnsworth-Hirsch fusors

A traditional Farnsworth-Hirsch fusor consists of a vacuum chamber containing a positively charged outer grid and a negatively charged inner grid; essentially a large vacuum tube with spherical grids. Fusible atomic nuclei are injected as ions into the system and accelerated toward the inner grid. Most of the time, the ions pass through the grid and enter the core where they either impact or miss other ions. On a miss (or non-fusing impact), the nuclei move outwards and pass through the inner grid which decelerates them and then reaccelerates them inward wherein they return through the core. Occasionally, given long enough, nuclei strike either the grid or another high-energy nucleus. Most strikes with other nuclei do not result in fusion, but occasionally fusion results.

A benefit with the Farnsworth-Hirsch fusor is that without the motion of electrons and magnetic fields, there are no synchrotron losses and (if the grid is kept cool to reduce thermionic emission) low levels of bremsstrahlung radiation.[1]

The fundamental problem with this traditional system is with the grid itself. Far too often, nuclei strike the grid. This damages the grid, wastes the energy that went into ionizing and accelerating the particle, and most critically, heats the grid. Even if the former problems were not critical, having a fine mesh grid in a reactor producing enough power to be used as a power plant would almost certainly mean that it would be rapidly vaporized.

Problems with Elmore-Tuck-Watson fusors

An Elmore-Tuck-Watson fusor inverts the charges on the grids. It consists of a vacuum chamber containing a negatively charged outer grid (which may be the chamber) and a positively charged inner grid. Electrons are injected into the system and accelerated toward the inner grid. Most of the time, the electrons pass through the grid, through the core, and through the inner grid again, which then decelerates them and reaccelerates them inward wherein they return through the core. As they pass repeatedly through the core, they generate a negatively charged zone, a potential well, which is call a virtual cathode. Fusible atomic nuclei are then introduced inside the positive grid where they are ionized. The virtual cathode accelerates the ions toward the center where they oscillate within the potential well. Since the ions never (in theory) reach the grid, they never lose their energy to such impacts and continue to oscillate through the core. Given enough oscillations, the ions strike other high-energy ions and fuse. The fundamental problem with this variation system is still the grid itself. Far too often the electrons strike the grid. Thus the Elmore-Tuck-Watson fusor has the same basic problems as the Farnsworth-Hirsch fusor.

The polywell approach

Like the Elmore-Tuck-Watson (ETW) fusor, the polywell confines positive ions through their attraction to the negative potential well which is created by the electrons that are held inside a positively charged grid. However, to avoid the losses related to the electrons striking the grid, the Polywell uses magnetic fields to shield the grid. The magnetic fields are configured in a way that adds to the confinement of the electrons so that there are many more electrons inside the core than outside.

The reactor volume is defined by the coils producing the magnetic field. The coils are held at a positive potential relative to the surrounding outer grid which may or may not be the walls of the vacuum chamber. This provides the same function as the positive and negative grids in the ETW fusor which is to restrain and return any electrons that escape the core. The charged coils are known as MaGrids, from "Magnetic Grids".

Ions are added at a density nearly equal to that of the electrons to produce a quasi-neutral plasma, but a slight excess of electrons maintains the negative potential well.[2] While this concept differs from the original ETW fusor in that it uses magnetic fields, it also differs from traditional magnetic confinement because the fields do not need to confine ions — only electrons, which is much easier.[3][4][5]

The polywell has electrons and ions existing in the same volume. While this avoids the limit on the fusor power density due to space charge effects, but it also introduces bremsstrahlung, which can be an important energy loss channel.[citation needed]

In most experiments to date, the patented MaGrid arrangement has been approximated by a symmetrical arrangement of discrete, circular coils, all pointing toward (or all away from) the center. The magnetic field vanishes at the center by symmetry, and the magnetic flux that enters the volume through the coils leaves it again through the spaces between the coils. This configuration confines electrons to the central volume by a magnetic mirror with a large field ratio or, under some conditions, a magnetic cusp. Bussard claimed[6] that the patented magnetic field has only point cusps but acknowledged that the circular coils produce line-like cusps at the closest approaches of the coils.

Polywell Geometry

cuboctahedron

If the configuration is looked at as solenoids on the faces of a polyhedron, then the polyhedron chosen must have an even number of faces at each vertex, so that the polarity of the solenoids can alternate. Infinitely many polyhedra satisfy this property, for example all antiprisms, 2n-agonal bipyramids, and all rectified (a.k.a. fully truncated) polyhedra. As can be seen from the picture above, the WB-6 coils can be mapped onto the red faces of the cuboctahedron to the right. Bussard's planned WB-7 would have been similar except it would have used "square plan form magnets" rather than circular and would have approximated the patented configuration more exactly. WB-8 would have been a pentagonal plan form magnet faced icosidodecahedron. Work at EMC2 since Dr. Bussard's death has resulted in different machines being assigned those numbers.

These geometries have several interesting properties. The shape of the magnetic potential well is the dual polyhedron of the machine. Each polyhedron could be constructed two different ways from circular coils. The edges of the polyhedron could also be wired directly as with Bussard's NPG polyhedral grid (there is an eulerian path because all vertices are even), but this is probably undesirable because every line passing through the center and a vertex will by symmetry have zero magnetic field.

Polywell Results

Despite initial difficulties in spherical electron confinement, at the time of the 2005 research project's termination, Bussard had reported a fusion rate of 109 per second running D-D fusion reactions at only 12.5 kV (based on detection of a total of nine neutrons in five tests,[7][8] giving a wide confidence interval). He claimed that the fusion rate achieved by WB-6 is roughly 100,000 times greater than that Farnsworth managed to achieve at similar well depth and drive conditions.[9][10] By comparison, researchers at the University of Wisconsin–Madison have claimed a neutron rate of up to 5×109 per second at voltages of 120 kV with an electrostatic fusor without magnetic fields.[11]

Bussard claimed that, assuming superconductors are used for the coils, the only significant energy loss channel is through electron losses proportional to the surface area. He also claimed that the density would scale with the square of the field (constant beta conditions), and the maximum attainable magnetic field would scale with the radius (technological constraints). Under those assumptions, the fusion power produced would scale with the seventh power of the radius, and the energy gain would scale with the fifth power. While Bussard had not publicly documented the physical reasoning underlying this estimate,[12] if true, it would enable a model only ten times larger to be useful as a fusion power plant.[7]

Comparison to conventional confinement concepts

The polywell is related to various other plasma confinement concepts, but differs markedly from all of them. It is most closely related to the fusor, which, like the polywell, confines ions by an inwardly directed electric field and requires a grid of solid-state electrodes within the plasma vessel. Both concepts intend to operate with a highly non-thermal, ideally mono-energetic, distribution of ion energies[4]. If the ion energies can be held near the optimum value, the fusion rate for a given plasma pressure can be a few times higher than the maximum rate possible for ions with a thermal distribution. On the other hand, collisions and collective instabilities have a tendency to restore a thermal distribution, so that it generally costs power to maintain a mono-energetic distribution.

The polywell differs from the fusor in that the electrons are magnetically confined, so that it is also related to magnetic confinement fusion, most closely to magnetic mirrors. In common with magnetic mirrors is the field minimum in the central region, the confinement (in part) by the mirror effect, and (at least to some extent) a non-thermal distribution of the electron energies. In some mirror configurations, the field in the center is a minimum in every direction, as it is in the central region of a polywell. The magnetic field in such a case is said to have "good curvature" because a certain class of fluctuations are stable in a plasma contained by such a field. In contrast to mirror machines, the polywell does not just have a minimum in the field strength in the center, the field vanishes entirely there. Also the polywell does not have a magnetic axis, but rather a polyhedral symmetry.

The most actively developed plasma confinement concept at this time is the tokamak, the concept behind ITER. A net power fusion reactor based on the tokamak concept, if possible, would certainly be a large and complex machine. The advocates of the polywell predict that a polywell reactor of similar power would be much smaller and simpler. The tokamak has a toroidal geometry with nested flux surfaces, so that both ions and electrons can only be lost by transport across magnetic field lines (primarily as a result of instabilities with very short wavelengths). The confinement of particles in a polywell is more complex, involving both magnetic and electric fields, transport of particles both across and along magnetic field lines, and different processes for the ions than for the electrons.

Possibility of net power

Bussard believed that this device can run with net energy production on boron-11 and proton fuel. Todd Rider calculates that bremsstrahlung losses with this fuel relative to the fusion production will be 1.20:1.00.[13] Bussard said that his calculation of the losses are about 5% of this, and therefore, greater gains than unity are possible.[14]

According to Bussard the high speed and therefore low cross section for Coulomb collisions of the ions in the core makes thermalizing collisions very unlikely, while the low speed at the rim means that thermalization there has almost no impact on ion velocity in the core.[7]

Another paper on the feasibility of IEC fusion, using the full bounce-averaged Fokker-Planck equation operator, concluded that IEC systems could produce large fusion energy gain factors (Q values). However, a deuterium-tritium reaction was necessary to minimize operating potential and Bremsstrahlung losses in order to reach large Q.[15]

History

File:Polywell WB-2.jpg
WB-2
File:Polywell WB-3.jpg
WB-3
File:Polywell WB-6 coils.jpg
WB-6 during assembly with coils showing

In the late 1960s there were several investigations of polyhedral magnetic fields as a possibility to confine a fusion plasma.[16][17] The first proposal to combine this magnetic configuration with an electrostatic potential well in order to improve electron confinement was made by Lavrent’ev in 1975.[18]

The idea was picked up by Robert Bussard in 1983, a link acknowledged in the references cited by his 1989 patent application[6], though in 2006 he appears to claim to have re-discovered the idea independently.[19] Research was funded by the Department of Defense beginning in 1987, and the United States Navy began providing low-level funding to the project in 1992.[20] Bussard, who had formerly been an advocate for Tokamak research, became the premiere advocate for and researcher on the concept, so that the idea is now indelibly associated with his name. In 1995 he sent a letter to the United States Congress stating that he had only supported Tokamaks in order to get fusion research sponsored by the government, but he now believed that there are better alternatives to Tokamaks.

Polywell models were produced through an iterative process, ranging from WB-1 through WB-6 (with WB-7 and 8 planned, but not constructed by Bussard's team; see FY2008-9 sections below for details on current WB-7 and WB-8 models). Early designs consisted of tightly welded stainless steel cubes of electromagnets, wound on square-cross section spools. These designs suffered from "funny cusp" losses at the joints between magnets, and from the magnetic field clipping the corners of the spools. The losses into the metal severely hurt their performance, leading to lower electron trapping performance than predicted. Later designs (starting with WB-6) began spacing electromagnets apart instead of touching, and changed to circular cross sections instead of square, reducing the metal surface area unprotected by magnetic fields. These changes dramatically improved system performance, leading to a great deal of electron recirculation and the confinement of electrons into a progressively tighter core. Until 2005 all of the reactors have been 6-magnet designs built as a cube (or more specifically as a truncated cube). Bussard's WB-8 was planned to be a higher-order polyhedron, with 12 electromagnets (this design was not used in the actual WB-8 machine).

Funding became tighter and tighter. According to Bussard, "The funds were clearly needed for the more important War in Iraq."[10] An extra $900k of Office of Naval Research funding allowed the program to continue long enough to reach WB-6 testing in November 2005. The last-produced model, WB-6, produced a fusion rate of 109 per second. Drive voltage on the WB-6 tests was about 12.5 kV, with a resulting potential well depth of about 10 kV, thus deuterons arriving in the center of the machine will have a kinetic energy of 10 keV. By comparison, a Fusor running deuterium fusion at 10 kV would produce a fusion rate difficult to detect at all. Hirsch reported a fusion rate this high only by driving his machine to 150 kV and by using deuterium-tritium fusion (a much easier reaction). While the pulses of operation in WB-6 were sub-milliseconds, Bussard felt the conditions should represent steady state as far as the physics are concerned. Most critically, the models of the system indicate that a full-sized model, costing approximately $150–200M (depending on the fuel), should be an effective power plant, producing notably more energy than it consumes. A last-minute test of WB-6 ended prematurely when the insulation on one of the hand-wound electromagnets burned through, destroying the device. With no more funding during 2006 and partly 2007, the project's military-owned equipment was transferred across town to SpaceDev, which also hired three of the team's researchers.[10]

After the transfer, Bussard tried to attract new investors, giving talks trying to raise interest in his design. A talk at Google headquarters had the title, "Should Google Go Nuclear?"[21] An informal overview of the last decade of work was presented at the 57th International Astronautical Congress in October 2006.[7]

Dr. Bussard formed EMC2 Fusion Development Corporation, [1] a non-profit organization, to seek funding for continuation of the project.

Recent Navy Funded Work

With the success of WB-6, Bussard believed that the system had demonstrated itself to the degree that no intermediate-scale models would be needed, and noted, "We are probably the only people on the planet who know how to make a real net power clean fusion system"[9] He proposed to rebuild WB-6 more robustly to verify its performance. After conducting and publishing the results of dozens of repeatable tests, he planned to convene a conference of experts in the field in an attempt to get them behind his design. Assuming his design had been backed, the project would have immediately moved toward a full-scale demo plant. The first step in that plan was to design and build two more small scale designs (WB-7 and WB-8) to determine which full scale polyhedral potential well would be best. He wrote “The only small scale machine work remaining, which can yet give further improvements in performance, is test of one or two WB-6-scale devices but with “square“ or polygonal coils aligned approximately (but slightly offset on the main faces) along the edges of the vertices of the polyhedron. If this is built around a truncated dodecahedron, near-optimum performance is expected; about 3-5 times better than WB-6.” [7]

Bussard noted that, "Thus, we have the ability to do away with oil (and other fossil fuels) but it will take 4-6 years and ca. $100-200M to build the full-scale plant and demonstrate it."[9]

Bussard said "Somebody will build it; and when it's built, it will work; and when it works people will begin to use it, and it will begin to displace all other forms of energy."[22]

FY 2008 Work

In August 2007, EMC2 received a $1.8M U.S. Navy research contract to continue the reactor development.[23] Prior to Bussard's death in October, 2007,[24] Dolly Gray, who co-founded EMC2 with Bussard in 1985, and served as its president and CEO, helped assemble the small team of scientists in Santa Fe to carry on his work. The group is led by Richard (Rick) Nebel and includes Jaeyoung Park; (both Nebel and Park are physicists on leave from the Los Alamos National Laboratory (LANL)); Mike Wray, the physicist who ran the key 2005 tests; and Kevin Wray, who is the computer specialist for the operation.

What is now called WB-7, the more robust version of the WB-6 fusion device, was constructed at a machine shop in San Diego and shipped to Santa Fe to the EMC2 testing facility. The device, like previous ones, was designed by engineer Mike Skillicorn. This WB-7 however was not the “square” coil suggested by Dr. Bussard.

WB-7, achieved "1st plasma" in early January, 2008.[25][26]

No specific information has been published at this moment, due to a publishing embargo on research data maintained by US Navy.[27] The previous project, led by the late Dr. Bussard, had been under an embargo for 11 years between 1994 and 2005 when that series of contracts with the US Navy ended.

In August 2008, the team finished the first phase of their experiment and were waiting for the peer review of their results and a verdict from their federal funders on whether the experiment should proceed to the next phase. Dr. Nebel has said "we have had some success", referring to the team's effort to reproduce the promising results obtained by Dr. Bussard. "It's kind of a mix", Dr. Nebel reported. But he stated that the team has "a plan to go forward." "We're generally happy with what we've been getting out of it, and we've learned a tremendous amount" he also said.[28]

FY 2009 Work

In September 2008 the Naval Air Warfare Center, Weapons Division, China Lake, CA publicly pre-solicited a contract for research on an Electrostatic "Wiffle Ball" Fusion Device[29]. the pre-solicitation was targeted toward EMC2 as preferred supplier.

In October 2008 the US Navy publicly pre-solicited two more contracts[30][31] also targeted toward EMC2 as preferred supplier. These two tasks were to develop better instrumentation and to develop an ion injection gun. Rick Nebel commented "This isn't a big deal. This is small, interim funding. It's called staying alive until they make a decision."[32] Other than Dr. Nebel's comments, there is no direct evidence that these pre-solicitations ever went to award.

In December 2008, following many months of review by the expert review panel of the submission of the final WB-7 results, Dr Richard Nebel commented that "There's nothing in there [the research] that suggests this will not work," but that "That's a very different statement from saying that it will work."

Stephen Chu, Nobel laureate and as of 2009 United States Secretary of Energy, answered a question about Polywell at a talk at Google in 2007, saying "So far, there's not enough information so [that] I can give an evaluation of the probability that it might work or not...But I'm trying to get more information."[33]

In January 2009 the Naval Air Warfare Center pre-solicited another contract for "modification and testing of plasma wiffleball 7"[34] which appears to be funding to install the instrumentation developed in a prior contract, install a new design for the connector (joint) between coils, and operate the WB-7 with the modifications. The modified unit is now called WB-7.1. This pre-solicitation started as a $200k contract but the final award was for $300k, which suggests that the earlier pre-solicitations were included in this one.

In April 2009, the DoD published a plan to provide Polywell a further $2 million in funding as part of the American Recovery and Reinvestment Act 2009. The citation in the legislation was labelled as Plasma Fusion (Polywell) - Demonstrate fusion plasma confinement system for shore and shipboard applications; Joint OSD/USN project.[35] The citation occurs 166 pages into the document, and suggests development of the device for 'Domestic Energy Supply / Distribution'.

In May 2009, Richard Nebel was interviewed in a popular science/futurism blog. He stated: "We are hoping to have a net energy production product within six years. It could take longer, but this definitely won't be a 50 year development project. [...] So if the concept works we could have a commercial plant operating as early as 2020."[36]

In September 2009, the FBO (Federal Business Opportunities web site) confirmed the award of Recovery Act funding under Navy contract in the amount of $7.86M for the construction and testing of WB-8, the next Polywell prototype. This device will have an eightfold increase in magnetic field strength compared to previous WB series devices, with the expectation of higher performance. Of particular importance within the Navy contract is the option for an additional $4.46M for ...based on the results of WB8 testing, and the availability of government funds the contractor shall develop a WB machine (WB8.1) which incorporates the knowledge and improvements gained in WB8. It is expected that higher ion drive capabilities will be added, and that a “PB11” reaction will be demonstrated.[37]

In September 2009, the US Department of Defense announced this award as required by law. The announcement stated that the funding was provided for research, analysis, development, and testing in support of the Plan Plasma Fusion (Polywell) Project. Efforts under this Recovery Act award will validate the basic physics of the Plasma Fusion (Polywell) concept, as well as provide the Navy with data for potential applications of polywell fusion. [38] The basic contract for WB-8 is expected to be completed by April 2011. The optional contract for WB-8.1 has a completion date of 31-Oct-2012.

See also

References

  1. ^ Andrew Seltzman (2008-05-30). "Design Of An Actively Cooled Grid System To Improve Efficiency In Inertial Electrostatic Confinement Fusion Reactors" (PDF). www.rtftechnologies.org. Retrieved 2009-08-14.
  2. ^ US patent 5,160,695, Robert W. Bussard, "Method and apparatus for creating and controlling nuclear fusion reactions", issued 1992-11-03 
  3. ^ Krall, Nicholas A. (1995). "Forming and maintaining a potential well in a quasispherical magnetic trap". Physics of Plasmas. 2 (1): 146–158. doi:10.1063/1.871103. ISSN 1070664x Parameter error in {{issn}}: Invalid ISSN. /Forming_and_maintaining_a_potential_well_Krall_Bussard_1995.pdf. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); line feed character in |id= at position 330 (help)
  4. ^ a b Bussard, Robert W. (1991). "Some physics considerations of magnetic inertial-electrostatic confinement ;A new concept for spherical converging-flow fusion". Fusion Technology. 19 (2): 273–293. ISSN 07481896 Parameter error in {{issn}}: Invalid ISSN. /Some_physical_Considerations_Bussard_FusionTechnology_1991.pdf. {{cite journal}}: line feed character in |id= at position 330 (help)
  5. ^ Krall, Nicholas A. (1992). "The Polywell ;A spherically convergent ion focus concept". Fusion Technology. 22 (1): 42–49. ISSN 07481896 Parameter error in {{issn}}: Invalid ISSN. /Polywell_spherically_convergent_ion_focus_concept_Fusion_Technology_Krall_1992.pdf. {{cite journal}}: line feed character in |id= at position 330 (help)
  6. ^ a b US patent 4,826,646, Robert W. Bussard, "Method and apparatus for controlling charged particles", issued 1989-05-02 
  7. ^ a b c d e "The Advent of Clean Nuclear Fusion: Super-performance Space Power and Propulsion", Robert W. Bussard, Ph.D., 57th International Astronautical Congress, October 2–6, 2006
  8. ^ Final Successful Tests of WB-6, EMC2 Report, currently (July 2008) not publicly available
  9. ^ a b c Robert W. Bussard (2006-03-29). "Inertial Electrostatic Fusion systems can now be built". fusor.net forums. Retrieved 2006-12-03.
  10. ^ a b c SirPhilip (posting an e-mail from "RW Bussard") (2006-06-23). "Fusion, eh?". James Randi Educational Foundation forums. Retrieved 2006-12-03.
  11. ^ UW–IEC Project
  12. ^ Possibly he was assuming that the ion energy distribution is fixed, that the magnetic field scales with the linear size, and that the ion pressure (proportional to density) scales with the magnetic pressure (proportional to B²). The R7 scaling results from multiplying the fusion power density (proportional to density squared, or B4) with the volume (proportional toR³). On the other hand, if it is important to maintain the ratio of the Debye length or the gyroradius to the machine size, then the magnetic field strength would have to scale inversely with the radius, so that the total power output would actually be lower in a larger machine.
  13. ^ Fundamental limitations on fusion systems not in equilibrium p161
  14. ^ "Bremsstrahlung Radiation Losses in Polywell Systems", R.W. Bussard and K.E. King, EMC2, Technical Report EMC2-0891-04, July, 1991
  15. ^ "Energy gain calculations in Penning fusion systems using a bounce-averaged Fokker–Planck model", Chacon, Barnes, Miley and Knoll, Phys. Plasmas 7, 4547 (2000); DOI:10.1063/1.1310199
  16. ^ R.Keller and I.R.Jones, "Confinement d'un Plasma par un Systemem Polyedrique a' Courant Alternatif", Z. Naturforschung, Vol. 21 n, pp. 1085-1089 (1966), as cited by R.W.Bussard in U.S.Patent 4,826,646, "Method and apparatus for controlling charged particles", issued May 2, 1989, p.12.
  17. ^ "Spherical Multipole Magnets for Plasma Research", Sadowsky, M., Rev.Sci.Instrum. 40 (1969) 1545
  18. ^ "Electrostatic and Electromagnetic High-Temperature Plasma Traps", O.A.Lavrent’ev, Conference Proceedings, Electrostatic and Electromagnetic Confinement of Plasmas and the Phenomenology of Relativistic Electron Beams, Ann. N.Y. Acad. Sci. 251, (1975) 152-178, as cited by Todd H. Rider in "A general critique of inertial-electrostatic confinement fusion systems", Phys. Plasmas 2 (6), June 1995. Rider specifically stated that "Bussard has revived an idea originally suggested by Lavrent’ev".
  19. ^ Posted to the web by Robert W. Bussard (2006). "A quick history of the EMC2 Polywell IEF concept" (Microsoft Word document). Energy/Matter Conversion Corporation. Retrieved 2006-12-03. {{cite web}}: Unknown parameter |month= ignored (help)
  20. ^ Posted to the web by Robert W. Bussard. "Inertial electrostatic fusion (IEF): A clean energy future" (Microsoft Word document). Energy/Matter Conversion Corporation. Retrieved 2006-12-03.
  21. ^ Dr. Robert Bussard (lecturer) (2006-11-09). "Should Google Go Nuclear? Clean, cheap, nuclear power (no, really)" (Flash video). Google Tech Talks. Google. Retrieved 2006-12-03.
  22. ^ Hosted by Dr. David Livingston (2007-05-08). "The Space Show". Episode 709 with guests Dr. Robert W Bussard, Thomas A Ligon. {{cite episode}}: External link in |number= and |title= (help); Missing or empty |series= (help)
  23. ^ "Funding Continues for Bussard's Fusion Reactor". New Energy and Fuel. 2007-08-27. Note that this source is a blog and not necessarily reliable.
  24. ^ William Matthews (2007-11-06). "Fusion Researcher Bussard Dies at 79" (webpage). Online article. Defencenews.com. Retrieved 2007-11-06.
  25. ^ "Strange Science Takes Time". MSNBC. 2008-01-09.
  26. ^ "Fusion Quest Goes Forward". MSNBC. 2008-06-12.
  27. ^ There is this clause in the "SOLICITATION, OFFER AND AWARD" for the "plasma wiffleball development project", awarded on March 3, 2009, to Matter Conversion Corporation:

    5252.204-9504 DISCLOSURE OF CONTRACT INFORMATION (NAVAIR) (JAN 2007) (a) The Contractor shall not release to anyone outside the Contractor’s organization any unclassified information (e.g., announcement of contract award), regardless of medium (e.g., film, tape, document), pertaining to any part of this contract or any program related to this contract, unless the Contracting Officer has given prior written approval. (b) Requests for approval shall identify the specific information to be released, the medium to be used, and the purpose for the release. The Contractor shall submit its request to the Contracting Officer at least ten (10) days before the proposed date for release. (c) The Contractor agrees to include a similar requirement in each subcontract under this contract. Subcontractors shall submit requests for authorization to release through the prime contractor to the Contracting Officer.

  28. ^ Posted to the web by Alan Boyle (2008). "Fusion effort in Flux" (HTML document). MSNBC. Retrieved 2008-09-08. {{cite web}}: Unknown parameter |month= ignored (help)
  29. ^ "A--Fusion Device Research, Solicitation Number: N6893608T0283" (HTML document). Federal Business Opportunities. 2008. Retrieved 2008-10-02. {{cite web}}: Unknown parameter |month= ignored (help)
  30. ^ "A--Polywell Fusion Device Research, Solicitation Number: N6893609T0011" (HTML document). Federal Business Opportunities. 2008. Retrieved 2008-11-07. {{cite web}}: Unknown parameter |month= ignored (help)
  31. ^ "A--Spatially Resolved Plasma Densities/Particle Energies, Solicitation Number: N6893609T0019" (HTML document). Federal Business Opportunities. 2008. Retrieved 2008-11-07. {{cite web}}: Unknown parameter |month= ignored (help)
  32. ^ "Found this during google search on Polywell Fusion" (Discussion forum). Talk-Polywell.org. 2008. Retrieved 2008-11-07. {{cite web}}: Unknown parameter |month= ignored (help)
  33. ^ "Fusion we can believe in?" (Science subsite of MSNBC.com). MSNBC.com. 2008. Retrieved 2008-12-18. {{cite web}}: Unknown parameter |month= ignored (help)
  34. ^ "A--Plasma Wiffleball, Solicitation Number: N6893609R0024" (HTML document). Federal Business Opportunities. 2009. Retrieved 2009-01-26. {{cite web}}: Unknown parameter |month= ignored (help)
  35. ^ "American Recovery and Reinvestment Act of 2009 - Department of Defense Expenditure Plans" (PDF Report to US Congress). Defencelink.mil. 2009. Retrieved 2009-05-05. {{cite web}}: Unknown parameter |month= ignored (help)
  36. ^ "Interview Dr. Richard Nebel of IEC/Bussard Fusion Project" (HTML document). Next Big Future. 2009. Retrieved 2009-05-05. {{cite web}}: Unknown parameter |month= ignored (help)
  37. ^ "Statement of work for advanced gaseous electrostatic energy (AGEE) concept exploration" (PDF document). United States Navy. 2009. Retrieved 2009-06-18. {{cite web}}: Unknown parameter |month= ignored (help)
  38. ^ "U.S. Department of Defense - Office of the Assistant Secretary of Defense (Public Affairs) - Contracts" (HTML document). United States Department of Defence. 2009. Retrieved 2009-09-13. {{cite web}}: Unknown parameter |month= ignored (help)

External links

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