Efficient compact fusion reactor

#The present application relates to a compact fusion reactor operated at high toroidal field. In particular, though not exclusively, the invention relates to a spherical tokamak reactor suitable for use as an energy source or as a highly efficient neutron source

#The challenge of producing fusion power is hugely complex. Many alternative devices apart from tokamaks have been proposed, though none have yet produced any results comparable with the best tokamaks currently operating such as JET.

#World fusion research has entered a new phase after the beginning of the construction of ITER, the largest and most expensive (c15bn Euros) tokamak ever built. The successful route to a commercial fusion reactor demands long pulse, stable operation combined with the high efficiency required to make electricity production economic. These three conditions are especially difficult to achieve simultaneously, and the planned programme will require many years of experimental research on ITER and other fusion facilities, as well as theoretical and technological research. It is widely anticipated that a commercial fusion reactor developed through this route will not be built before 2050.

#Some preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

#FIG. 1 shows a comparison of Low Temperature Superconductor (LTS) (left side) with 1st and 2nd generation HTS. The HTS material offers similar performance in a given magnetic field but at higher and more convenient temperatures; however if cooled to low temperatures (e.g. the 4K used for LTS) it can carry substantially higher current than LTS.

#FIG. 2 shows the critical current as a function of magnetic field for an HTS sample at different temperatures;

#The present application is based on a very compact form of the tokamak, and employs a range of innovative features, including use of High Temperature Superconducting magnets. The ‘Efficient Compact Fusion Reactor’ (ECFR) is intended to provide a compact fusion power plant.

#Fusion neutrons are produced when a deuterium-tritium (D-T) or deuterium-deuterium (D-D) plasma becomes very hot so that the nuclei fuse together, releasing energetic neutrons. To date, the most promising way of achieving this is to use a tokamak; in the conventional tokamak approach to fusion (as embodied by ITER), the plasma needs to have high confinement time, high temperature, and high density to optimise this process.

#A tokamak features a combination of strong toroidal magnetic field BT, high plasma current Ip and usually a large plasma volume and significant auxiliary heating, to provide a hot stable plasma so that fusion can occur. The auxiliary heating (for example via tens of megawatts of neutral beam injection of high energy H, D or T) is necessary to increase the temperature to the sufficiently high values required for nuclear fusion to occur, and/or to maintain the plasma current.