March 18, 2009

General Fusion Research Update

General Fusion is using the MTF (Magnetized Target Fusion) approach but with a new, patent pending and cost-effective compression system to collapse the plasma. They describe the injectors at the top and bottom of the above image in the new research paper. The goal is to build small fusion reactors that can produce around 100 megawatts of power. The company claims plants would cost around US$50 million, allowing them to generate electricity at about four cents per kilowatt hour.

If there are no funding delays, then in 2010-2011 for completion of the tests and work for an almost full scale version (2 meters instead of 3 meter diameter).

The third phase for General Fusion is to raise $50 million for a net energy gain device with a target date of 2013 if the second/third phase are roughly on schedule.

If they get $300-500 million for commercialization, the first commercial scale unit could be 2016-2018.

Note: Any fusion power system would have applications for space. Lowering energy costs helps with space. Better and lighter power systems are good for space colonies and industrialization.

General Fusion will build a ~3 meter diameter spherical tank filled with liquid metal (lead-lithium mixture). The liquid is spun to open up a vertical cylindrical cavity in the center of the sphere (vortex). This vortex flow is established and maintained by an external pumping system; the liquid flows into the sphere through tangentially directed ports at the equator and is pumped out radially through ports near the poles of the sphere. Two spheromaks (self confined magnetized plasma rings) composed of the deuterium-tritium fuel are then injected from each end of the cavity. They merge in the center to form a single magnetized plasma target. The outside of the sphere is covered with pneumatic rams. The rams use compressed gas to accelerate pistons to ~50 m/s. These pistons simultaneously impact a set of stationary anvil pistons at the surface of the sphere, which collectively launch a high pressure spherical compression wave into the liquid metal. As the wave travels and focuses towards the center, it becomes stronger and evolves into a strong shock wave. When the shock arrives in the center, it rapidly collapses the cavity with the plasma in it. At maximum compression the conditions for fusion are briefly met and a fusion burst occurs releasing its energy in fast neutrons. The neutrons are slowed down by the liquid metal causing it to heat up. A heat exchanger transfers that heat to a standard steam cycle turbo-alternator to produce electricity for the grid. Some of the steam is used to run the rams. The lithium in the liquid metal finally absorbs the neutrons and produces tritium that is extracted and used as fuel for subsequent shots. This cycle is repeated about one time per second.

General Fusion report on the development of compact toroid (CT) accelerators to create the target plasma for magnetized target fusion (MTF) devices. Due to the requirements of high initial density of *10^17 cm-3, strong internal fields of 5–10 T, and base temperatures of [100 eV, a design based on conical compression electrodes is an effective avenue to pursue. Progress is being made at General Fusion Inc, (Vancouver, Canada) to develop a pair of large CT accelerators for generating an MTF target plasma. In this design, tungsten coated conical electrodes (with a formation diameter of 1.9 m, a radial compression factor of 4, and overall accelerator length of 5 m) will be used to achieve ohmic heating and acceleration of the CT, yet with low wall sputtering rates. A pair of these accelerators can be synchronized and shot at one another, producing a collision and reconnection of the two CTs within the center of an MTF chamber. Depending on the choice of relative helicities, the two CTs will merge to form either a spheromak-like or an FRC-like plasma. [FRC is field reversed configuration.

An FRC (field reversed configuration) is an elongated plasma ellipsoid conducting an azimuthal current which reverses the direction of an externally applied magnetic field. The resultant field provides for toroidal plasma confinement without requiring a toroidal vacuum vessel or coil set.

Experimental Results from the First Proof of Concept System

General Fusion proposes a new MTF concept requiring precise pneumatic impact drivers. We have built one such driver and achieved so far an open loop impact velocity of 17 m/s. Impact velocity approaching 100 m/s with precise close loop control will be required

General fusion had raised $7 million out of a needed $10 million for the second round.

General Fusion pictures and Video

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