Smaller & Sooner: Exploiting High Magnetic Fields from New Superconductors for a More Attractive Fusion Energy Development Path

Abstract

The current fusion energy development path, based on large volume moderate magnetic B field devices is proving to be slow and expensive. A modest development effort in exploiting new superconductor magnet technology development, and accompanying plasma physics research at high-B, could open up a viable and attractive path for fusion energy development. This path would feature smaller volume, fusion capable devices that could be built more quickly than low-to-moderate field designs based on conventional superconductors. Fusion's worldwide development could be accelerated by using several small, flexible devices rather than relying solely on a single, very large device. These would be used to obtain the acknowledged science and technology knowledge necessary for fusion energy beyond achievement of high gain. Such a scenario would also permit the testing of multiple confinement configurations while distributing technical and scientific risk among smaller devices. Higher field and small size also allows operation away from wellknown operational limits for plasma pressure, density and current. The advantages of this path have been long recognized-earlier US plans for burning plasma experiments (compact ignition tokamak, burning plasma experiment, fusion ignition research experiment) featured compact high-field designs, but these were necessarily pulsed due to the use of copper coils. Underpinning this new approach is the recent industrial maturity of high-temperature, highfield superconductor tapes that would offer a truly ''game changing'' opportunity for magnetic fusion when developed into large-scale coils. The superconductor tape form and higher operating temperatures also open up the possibility of demountable superconducting magnets in a fusion system, providing a modularity that vastly improves simplicity in the construction, maintenance, and upgrade of the coils and the internal nuclear engineering components required for fusion's development. Our conclusion is that while tradeoffs exist in design choices, for example coil, cost and stress limits versus size, the potential physics and technology advantages of high-field superconductors are attractive and they should be vigorously pursued for magnetic fusion's development.

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

“…As a closing remark to this section, we recognize that along with the HEP community, the fusion community has consistently identified REBCO high-field magnets as a transformative enabling technology for the magnetic fusion devices towards energy generation [203][204][205][206][207][208][209]. With the strong synergy between the high-field accelerator and fusion magnets [19,142,210], the research needs discussed here can also be leveraged for the development of high-field fusion conductors and magnets (Table 2).…”

Nuclear Fusion Power Plants

“…Recent developments in magnet technology has seen the development of high-temperature superconductors (HTS) which can carry greater currents at Nuclear Fusion Power Plants http://dx.doi.org/10.5772/intechopen.80241 higher field than LTS, and with greater cryogenic efficiency, owing to the operating temperature ("high-temperature" is a misnomer that refers to potential high-performance magnet operation at 20-30 K, rather than 4 K). Development in HTS, which may lead to the development of more efficient smaller fusion reactors as they are capable of operating at higher field [22,27].…”

“…Delays to the public fusion program, combined with novel ideas, disruptive technologies, and an injection of private funding has led to the birth of a number of private-sector start-ups, all looking for a faster route to fusion [47]. Both Tokamak Energy Ltd in the UK, and Commonwealth Fusion Systems, a spin-out company from MIT in the US, are developing tokamak variants that operate on alternative high-performance plasma regimes that make use of the benefits of HTS magnets [22,27].…”

“…With this in mind, it could appear disingenuous to make the same statement here at the current time, but the realization Figure 6. Current timeline for the commercialization of nuclear fusion energy [15,22,27,43,44,48].…”

Preface to the Special Issue: Strategic Opportunities for Fusion Energy

“…Raman et al [9] describe deep particle fueling and momentum injection using compact tori (CT) and using off-axis current drive from electron Bernstein waves (EBW) in order to optimize the performance of the steadystate advanced tokamak and spherical tokamak. Whyte et al [10] describe how the recent industrial maturity of high-temperature, high-field superconductors open up the possibility of more compact fusion reactors and the design of demountable and modular magnets that vastly improves simplicity in the construction and maintenance of the coils and the internal components required for fusion. Pace et al [11] describe experiments that can be performed using today's research tokamaks to investigate the feasibility of enhanced fusion yield with spin polarized fuel.…”