Robert W. Bussard

Robert W. Bussard (August 11 1928 – October 6 2007) was an American physicist who worked primarily in nuclear fusion energy research. He was the recipient of the Schreiber-Spence Achievement Award for STAIF-2004.^[1] He was also a fellow of the International Academy of Astronautics.

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Kiwi (Rover-A)

In 1956, Bussard designed the nuclear thermal rocket known as project Rover.

Two important monographs on nuclear propulsion were written by Bussard and DeLauer:

• Nuclear Rocket Propulsion^[2].

• Fundamentals of Nuclear Flight^[3].

Bussard Ramjet

In 1960, Bussard conceived of the Bussard ramjet, an interstellar space drive powered by hydrogen fusion using hydrogen collected with a magnetic field from the interstellar gas. Due to the presence of high-energy particles throughout space, much of the interstellar hydrogen exists in an ionized state (H II regions) that can be manipulated by magnetic or electric fields. Bussard proposed using a large magnet to "scoop" up the ionized hydrogen and funnel it into a fusion reactor, using the exhaust from the reactor as a rocket engine. Since it would pick up its fuel from space, there was no apparent upper limit to the speed such a craft could achieve.There is an upper limit set by unavoidable transverse radiation from the hydrogen captured in the fusion process, which limits the effective radius of action of the starship using such a drive to only a few hundred lightyears.

It appears the energy gain in the reactor must be extremely high for the ramjet to work at all; any hydrogen picked up by the scoop must be sped up to the same speed as the ship in order to provide thrust, and the energy required to do so increases with the ship's speed. Hydrogen itself does not fuse very well at all (unlike deuterium, which is rare in the interstellar medium), and so cannot be used directly to produce energy, a fact which accounts for the billion-year scale of stellar lifetimes. Accordingly, some other process would be required.

Since the time of Bussard's original proposal, it has been discovered that the region surrounding the sun has much lower density of interstellar hydrogen than was believed at that time. This is of concern only because it requires larger scoops to collect the fuel required. Other studies (see Magnetic sail) have contended that drag will exceed thrust from such scoop designs. However, these neglected the momentum-conserving aspect of mirror capture and mirror reflection in the collection and exhaust streams of such systems.

This theoretical device description was used with good understanding and elaboration on the advantages and limitations of such a drive in science fiction novels by Poul Anderson: Tau Zero and Larry Niven: Protector and other of his Known Space stories.

A highly fictionalized variation of this concept appears in the Star Trek series as part of the "warp drive" that allowed Starfleet ships to travel faster than the speed of light. In the series, Bussard Collectors or Bussard Ramscoops were in place on the front of the warp nacelles, where they could scoop in interstellar gases for use by the ships' propulsion and power systems.

Atomic Energy Commission

In the early 1970s Dr. Bussard became Assistant Director under Director Robert Hirsch at the Controlled Thermonuclear Reaction Division of what was then known as the Atomic Energy Commission. They founded the mainline fusion program for the United States: the Tokamak. In June 1995, Bussard claimed in a letter to all fusion laboratories, as well as to key members of the US Congress, that he and the other founders of the program supported the Tokamak not out of conviction that it was the best technical approach but rather as a vehicle for generating political support, thereby allowing them to pursue "all the hopeful (sic) new things the mainline labs would not try". Bussard's Letter

International Nuclear Energy Systems Corporation

With fellow researcher Bruno Coppi, Bussard later founded Inesco, a private firm funded in part by Penthouse Magazine publisher Bob Guccione. Inesco set out to build small power-producing Tokamak fusion reactors called Riggatrons using methods developed from the MIT Alcator research Tokamaks, and based on proven engineering heat/power capabilities from the aerospace industry.

The device was a very small, normal copper, water-cooled system, with a lifetime of about 30-60 days, before death by neutron destruction of the first wall (of the magnets). It was thought that the system could be made economically attractive even though it was short-lived, because the fusion core was so small and cheap that it could be replaced, like a giant light bulb - with relative (to conventional large-scale Tokamaks) ease and low cost.

A test site had been selected and approved by the authorities, but never implemented. Development had proved difficult and costly, so that funds could not be found to build the $200 million test facility and test system, ending the program. It was shortly co-opted by the Department of Energy which renamed the system and held 2 national and 1 international conferences on it. This line of development was then transferred to Princeton, as TNX or The Next Step. Under Princeton the program was expanded and given greater funding, but an efficient working system like that originally envisioned has proven elusive. It still survives today, now called CIT (Compact Ignition Torus) within the PPPL/DoE framework.

Energy Matter Conversion Corporation

Together with his wife, Dolly H. Gray, Bussard co-founded a company (Energy Matter Conversion Corporation (EMC²) in 1984, to exploit his invention (in 1983) of a new method of inertial electrostatic confinement fusion. This was initially funded privately, then by the DoD SDIO, DNA, DARPA contract funding. This was a variant of the electric configuration published by Elmere, Tuck and Watson in the late 1950s, which was an inversion of that used by Farnsworth and Hirsch in later work, Inertial Electrostatic Confinement (IEC) Farnsworth-Hirsch fusor.

In an Analog magazine article, fellow fusion researcher Tom Ligon described an easily-built demonstration fusor system along with some of Bussard's ideas for fusion reactors and incredibly powerful spacecraft propulsion systems, with which spacecraft could swiftly move throughout the solar system.^[4]

The Polywell

Main article: Polywell

Bussard worked on a promising new type of gridless IEC fusor, called the Polywell, and built and tested several (15) experimental devices, from 1994 through 2006. The U.S. Navy contract funding that supported the work expired while experiments were still small. However, the final tests of the last device, WB-6, reputedly solved the last remaining physics problem just as the funding expired and the EMC² labs had to be shut down.

Appeal for Funding

During 2006 and 2007, Bussard sought the large-scale funding necessary to design and construct a full-scale Polywell fusion power plant. His fusor design is feasible enough, he asserted, to render unnecessary the construction of larger and larger test models still too small to achieve break-even. Also, the scaling of power with size goes as the seventh power of the machine radius, while the gain scales as the fifth power, so there is little incentive to build half-scale systems; one might as well build the real thing.

On March 29 2006, Bussard claimed on the fusor.net internet forum that EMC² has developed an inertial electrostatic confinement fusion process that was 100,000 times more efficient than previous designs, but that the US Navy budget line item that supported the work was zero-funded in FY2006.^[5]

Bussard provided more details of his breakthrough and the circumstances surrounding the end of his Navy funding in a letter to the James Randi Educational Foundation internet forum on June 23.^[6]

From October 2, 2006 to October 6, 2006, Bussard presented an informal overview of the previous decade of his work at the 57th International Astronautical Congress.^[7] This was the first publication of this work in 11 years, as the U.S. Navy had put an embargo on publications of the research, in 1994.

Dr. Bussard presented much more details of his IEC fusion research at a Google Tech Talk on November 9 2006, of which a video was widely circulated.^[8]

Bussard presented more of his thoughts on the potential world impact of fusion power at a Yahoo! Tech Talk on April 10, 2007.^[9] (The video is only available internally for Yahoo employees.) He also spoke on the internet talk radio show The Space Show on May 8 2007.

He founded a non-profit organization to solicit tax-deductible donations to restart the work in 2007. The organization is EMC2 Fusion Development Corporation, web site is EMC2Fusion.org ^[10]

Death

Bussard died from cancer on October 6 2007 at age 79. ^[11] His work will continue as funding was arranged and received on August 21, 2007 and he was able to create a staff of physicists to continue.

References

See also

• Farnsworth Fusor