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Special Topic Article Recent trends of nuclear fusion research by companies 3. Nuclear Fusion Research by Tri Alpha Energy
GOTA Hiroshi1) and BINDERBAUER Michl W. Tri Alpha Energy, Inc. 1)hgota@trialphaenergy.com
(Date Submitted: 10/27/2016)
Tri Alpha Energy’s research has been devoted to producing a high temperature, stable, long-lived field-reversed configuration (FRC) plasma state by colliding and merging two oppositely directed compact toroids and neutral-beam injection (NBI). The ultimate goal is to develop and operate a high-beta, magnetically-confined fusion reactor without neutron emission using advanced fuels such as p-11B. Recently, the C-2/C-2U experiments have demonstrated drastic improvements in particle and energy confinement properties of FRC’s, and the plasma performance obtained via ~10 MW NBI has achieved plasma sustainment of up to 5 ms and plasma (diamagnetism) lifetimes of 10+ ms. Those achievements and scientific advances are striking breakthroughs, and encourage further improvements / advances in the future.
Keywords:
field-reversed configuration, compact toroid, neutral-beam injection, plasma sustainment, aneutronic fusion, advanced fuel
3.1 TAE's Corporate Research Background
Tri Alpha Energy (TAE), located in Southern California, United States of America, was established in 1998 as a private company aiming for the development and steady operation of commercial fusion reactors and is currently one of the world's largest privately funded fusion-research companies [1]. The company was established by the late Professor Norman Rostoker of the University of California at Irvine (UCI), Professor Henk Monkhorst of the University of Florida (UF) and Dr. Michl Binderbauer. TAE still maintains their concept/vision and system of industry-academia collaboration. TAE's vision of a magnetically confined fusion reactor is based on utilizing the field-reversed configuration (FRC) [2, 3] as the core plasma and performing plasma heating and current driven by neutral-beam injection (NBI). The system eventually generates 8.7 MeV of energy from nuclear fusion by reacting hydrogen (p) and boron (11B). Appropriately, due to the generation of three alpha particles (3x 4He) from the p-11B nuclear fusion reaction, the company was named Tri Alpha Energy.
While the D-T fuel is mainly considered for use in fusion reactor development and for steady operation of large fusion devices, TAE’s approach is to adopt advanced fuels such as p-11B (D-3He is also possible) with the ultimately aim of a safe fusion reactor that does not generate neutrons in its primary fusion reaction, which have a negative impact on our human bodies. This approach also has many technological advantages that make it easier to design, develop and operate the reactor because there is little to no concern about neutron induced damage. However, the conditions for fusion reactions/burning plasmas are more difficult than those for D-T and D-D reactions; to achieve those final condition and realize steady-state operation is a future task.
Concerning the magnetic confinement concept and characteristics of FRCs, the attractiveness and advantages of adopting it as a fusion plasma
core, have been featured in this journal [4, 5] and in other scientific journals as review articles [2, 3]; an FRC-based fusion reactor concept called "ARTEMIS" was also proposed in the past [6]. In FRCs, the configuration is established solely by the poloidal magnetic field formed by the toroidal self-current. Plasma beta (ratio of plasma pressure to external magnetic pressure) is close to 100%, so FRCs can be compact, highly magnetically efficient and attractive as fusion reactor plasma. In addition, since the closed magnetic field line structure exists independently of the open magnetic field lines outside the FRC (separatrix), FRCs can be easily translated in the axial direction. Direct energy conversion is also enabled by using natural divertors at both ends of the device. At TAE, using a FRC core that essentially combines these attractive features, the plasma is sustained and heated by fast ions having a large Larmor radius generated by NBI. Eventually the aim is to use advanced fuels to achieve fusion reactions and break even.
Although the FRC research community in general of smaller scale than that of tokamaks and helical devices, which together form the mainstream of magnetic confinement efforts worldwide, experimental and theoretical research on FRC’s has been actively conducted in Japan and the U.S., including at TAE. Steady progress towards a viable fusion core plasma is the present situation. In recent years, experimental results of C-2/C-2U at TAE have shown remarkable progress, such as suppression of plasma instabilities and improvements in particle and energy confinement characteristics. Those have been the big concern and focus of the FRC research community for a long time [7-11]. By increasing the input power of the NBI system, the equilibrium FRC plasma lifetime was extended to 5+ ms (plasma/diamagnetism lifetime >10 ms) [12]. We call this improved FRC plasma state a High-Performance FRC (HPF) [10]. The HPF plasma state maintained via fast ions through a high power (10+ MW) NBI system is called an Advanced Beam-Driven FRC [12].
In the following sections, we describe TAE’s main experimental results obtained in the C-2/C-2U devices, together with an overview of the
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