Recently, we have seen multiple initiatives that were launched to push down the scale and cost of a fusion reactor, in attempts to work towards a commercial reactor that is cost effective.
Dennis Whyte and a team at MIT add one more compact tokamak design in a paper in the journal Fusion Engineering and Design. Key element of the design are new commercially available high-temperature superconductor tapes (as also used by for example Tokamak Energy), to produce high-magnetic field coils. The stronger magnetic field allows a smaller device size, making the device cheaper and opening the road to other reactor design improvements.
A cutaway view of the proposed ARC reactor.
Whyte says the acronym (“Affordable, Robust, Compact”) is not a reference to Iron Man’s power source...
We summarize the proposed features of this ARC reactor:
- The tokamak will have a major radius of 3.3m, which is half the size of ITER. In such small reactor designs, having a high magnitude magnetic field is essential to achieve sufficient confinement and stability, when trying to achieve large fusion powers (525 MW is targeted for ARC).
- ARC will use recently developed high-temperature barium copper oxide (REBCO) superconducting tapes to enable a large on-axis magnetic field (9.2 T). As a result the superconducting device might not only offer access to high plasma gain, but also enable net electric gain.
- The use of the REBCO tapes allows the use of resistive joints in the superconducting coils. As a result, the toroidal field coils can be made demountable, which can provide a dramatically different and perhaps more attractive modular maintenance scheme.
- The use of lower hybrid waves launched from the high field side of the tokamak as current drive will be explored. This is shown in modeling to increase the current drive efficiency and will reduce damage to the launcher.
- For cooling and tritium breeding, fluorione lithium beryllium (FLiBe) will flow through the double-walled vacuum vessel.
- ARC will explore the use of the I-mode regime. This mode is characterized by the L-mode like particle confinement time and the H-mode like energy confinement. It may be an attractive regime because it may allow for easier control of density and impurities, critical control features for burning plasmas.
For the full article, we refer to: