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This post examines a Google talk given by Dr. Robert W. Bussard in 2006. At the time of posting, the video was online at
In this video, Dr. Bussard discusses his Polywell inertial confinement (IEC) system for nuclear fusion. The Polywell is his improvement on the Farnsworth Fusor style of reactor. A Farnsworth Fusor (also known simply as a Fusor; see Fusor.net for specifications and build instructions) uses an anode grid to attract fusible ions to a center point, where they collide and fuse. The Fusor, designed in the sixties, never achieved energy positive nuclear fusion. The reason for this, as reported by Dr. Bussard, is that the ions passed through the grid many times before finally connecting with another ion. During their travels through the grid openings, many ions collided with the metal grid itself, causing damage to the grid and energy loss to the system. In the picture below, the inner grid is the anode and the outer is the cathode, encouraging the positive ions towards the interior.
Dr. Bussard attempted to remedy this problem by replacing the anode grid with an electron core. He realized that a cloud of electrons could be magnetically confined and used to attract positive ions. By building a pseudo-spherical confinement system, essentially magnetic bottles in x,y, and z directions, he hoped to minimize electron (and, by connection, ion) losses and maximize the reaction rate. (Below: Polywell)
Dr. Bussard believes that his style of fusion reactor is a more viable system than the currently popular tokamak design. A tokamak reactor confines a plasma in a torus using curved magnetic bottles and then induces a current in the plasma. This confinement scheme causes the ions to make small spirals within the torus. Dr. Bussard claims that with each collision of fusible ions causes each member involved to move a distance equal to the radius of this spiral. Over the many (~1000) interactions that will occur before ions finally fuse, many ions will collide with the walls of the tokamak. Bussard claims that his system will retain a higher number of ions than the tokamak reactors, and will therefore be more efficient.
Bussard’s team claims that the Polywell will also be cheaper to build and test than a tokamak. They claim that the difference in price is the difference between billions and millions of dollars. Despite the cheaper price of Polywell reactors, and Bussard’s ardent praise of their viability, Bussard and his team have trouble finding funding after being cut from the Department of Defense during a management shift.
The majority of the video is a series of explanations of the various models built by Bussard and his team. He explains several different ideas and experiments. For example, they found that round (along the circumference of the ring) magnets make a tremendous impact on the energy efficiency of the device. They also managed to use a 90$ microwave to ionize neutral particles, making them easier to deal with magnetically. They subsequently found out that the gargantuan voltage required in use of the device could cause massive arcing and ionization on its own. They found this arcing quite detrimental to their energy efficiency and also found that ionizing neutral particles flooded their core and inhibited fusion. This lead them to abandon their microwave sourced magnetron and to insulate every possible part within and near the device.
Dr. Bussard was a brilliant scientist who passed away in 2007. His work remains unfinished and incomplete.