High beta fusion reactor
The high-beta fusion reactor (also known as the 4th generation prototype T4) is a project being developed by a team led by Charles Chase of Lockheed Martin’s Skunk Works. The "high beta" configuration allows a compact fusion reactor design and speedier development timeline. It was first presented at the Google Solve for X forum on February 7, 2013.[1]
Lockheed Martin's plan is to "build and test a compact fusion reactor in less than a year with a prototype to follow within five years."[2]
Contents
History
The project began in 2010.[3]
In October 2014 Lockheed Martin announced that they will attempt to develop a compact fusion reactor that will fit "on the back of a truck" and produce 100 MW output - enough to power a town of 80,000 people.[4]
The chief designer and technical team lead for the Compact Fusion Reactor (CFR) is Thomas McGuire, who did his PhD dissertation[5][6] on fusors at MIT.[7] McGuire studied fusion as a source of space propulsion in graduate school in response to a NASA desire to improve travel times to Mars.[8][9][10]
Design
Lockheed Martin is using a combination of cusp confinement and magnetic mirrors to hold in the plasma. Cusps are sharply bent magnetic fields. Ideally, the plasma forms a sheath along the surface of the cusps and plasma will leak out through along the axis and edges of the sharply bent field.[11] This design attempts to recycle the plasma lost along the edges back into the cusps.
The CFR uses two mirror sets. A pair of ring mirrors is placed inside the cylindrical reactor vessel at either end. The other mirror set encircles the reactor cylinder. The ring magnets produce a type of magnetic field known as a diamagnetic cusp, in which the magnetic forces rapidly change direction and push the nuclei towards the midpoint between the two rings. The fields from the external magnets push the nuclei back towards the vessel ends.
One of the project's innovations is the use of superconducting magnets. They allow strong magnetic fields to be created with less energy than conventional magnets. The CFR has no net current, which Lockheed claims eliminates the prime source of plasma instabilities. The plasma also has a favorable surface-to-volume ratio, which improves confinement. The plasma's small volume reduces the energy needed to achieve fusion. The project plans to replace the microwave emitters that heat the plasma in their prototypes with neutral beam injection, in which electrically neutral deuterium atoms transfer their energy to the plasma. Once initiated, the energy from fusion maintains the necessary temperature for subsequent fusion events. The CFR's beta (ratio of plasma pressure to magnetic field pressure) is an order of magnitude greater than in tokamaks.[3]
Lockheed Martin is targeting a relatively small device that is approximately the size of a conventional jet engine. The prototype is approximately 1 meter by 2 meters in size. The company claims that this enables a much faster development cycle since each design iteration could be produced more quickly and at far lower cost than large-scale projects such as the Joint European Torus or ITER.[12]
Challenges
The ring magnets require protection from the plasma's damaging neutron radiation. Also plasma temperatures must reach many millions of Kelvin. The magnets have to be kept just above absolute zero to maintain superconductivity.[3]
The 'blanket' component that lines the reactor vessel has two functions: it captures the neutrons and transfers their energy to a coolant and forces the neutrons to collide with lithium atoms, transforming them into tritium to fuel the reactor. The weight of the blanket is a key element for mobile applications. The project estimates that it could weigh 300–1000 tons.[3]
Projects
T-4
Technical results presented on the T4 experiment by Dr. Tom McGuire in 2015 showed a cold, partially ionized plasma with the following parameters: peak electron temperature of 20 Electron volts, 1E-16 m-3 electron density, less than 1% ionization fraction, and 3 kW of input power. No confinement or fusion reaction rates were presented.
Two theoretical reactor concepts were presented by Tom McGuire in 2015. An ideal configuration weighing 200 metric tons with 1 meter of cryogenic radiation shielding and 15 Tesla Magnets. A conservative configuration weighing 2,000 metric tons, 2 meters of cryogenic radiation shielding, and 5 Tesla magnets was also presented.[13]
Patents
Lockheed Martin has applied for three patents US application 20140301518A1,US application 20140301519A1 and US application 20140301517A1.
Criticism
Physics professor and director of the UK's national Fusion laboratory Steven Cowley called for more hard data, pointing out that the current thinking in fusion research is that "bigger is better". Other fusion reactors achieve 8 times improvement in heat confinement when machine size is doubled.[14]
See also
- Beta (plasma physics)
- Fusor
- Inertial electrostatic confinement
- Magnetic mirror
- Polywell
- Fusion power
- ARC fusion reactor
References
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- ↑ McGuire, Thomas. "The Lockheed Martin Compact Fusion Reactor." Thursday Colloquium. Princeton University, Princeton. 6 Aug. 2015. Lecture.
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