Abstract: A cooling system for use in a superconducting magnet comprising a high temperature superconductor, HTS, coil. The cooling system comprises a refrigeration unit, one or more coolant channels, and a pumping unit. The refrigeration unit is configured to cool a gas, wherein the gas is hydrogen or helium. The one or more coolant channels are configured to be placed in thermal contact with components of the superconducting magnet and to carry said gas. The pumping unit is configured to pump said gas through the coolant channels. The refrigeration unit and pumping unit are configured to maintain the gas at a pressure and temperature such that a Joule-Thompson coefficient of the gas is positive, and the coolant channel is configured to reduce the pressure of gas as it flows through the channel by one or more of a throttle, a valve, and choice and/or variance of a cross section of the coolant channel.

Abstract: There is described neutron shielding for a nuclear fusion reactor. The neutron shielding includes a cemented carbide or boride comprising a binder and an aggregate, the aggregate comprising particles of a carbide or boride compound.

Abstract: A tokamak comprising a toroidal containment vessel and a plasma initiation system. The toroidal containment vessel is configured to contain a plasma. The plasma initiation system comprises upper and lower poloidal field, PF, coil sets. Each PF coil set comprises at least one inner PF coil located outside of the containment vessel, an outer PF coil located inside the containment vessel, and shielding located between the outer PF coil and a location of the plasma during operation of the tokamak and configured to protect the outer PF coil from heat emitted by the plasma. The inner and outer PF coils are configured so as to form a PF null within the containment vessel between the inner and outer PF coils, such that the upper and lower PF coil pairs are operable to initiate a plasma in the containment vessel via double null merging.

Abstract: A toroidal field coil for generating a toroidal magnetic field in a nuclear fusion reactor includes a toroidal plasma chamber having a central column. The toroidal field coil has a plurality of windings configured to pass through the central column and around the outside of the plasma chamber. Each winding includes a cable having a plurality of stacked high temperature superconductor (HTS) tapes, each HTS tape including one or more layers of a high temperature superconductor material. With the toroidal field coil in place in the reactor, a face of each HTS tape is substantially perpendicular to a direction of maximal neutron flux during reactor operation as the cable passes through the center column.

Abstract: A toroidal field coil for generating a toroidal magnetic field in a nuclear fusion reactor comprising a toroidal plasma chamber having a central column. The toroidal field coil comprises a portion passing through the central column. The portion passing through the central chamber comprises: ?a low temperature superconductor, LTS, layer (21) formed from LTS; ?a high temperature superconductor, HTS, layer (22) formed from HTS and located radially outward of the LTS layer. ?a non-superconducting conductive layer (23) formed from electrically conducting, non-superconducting material and located radially outward of the HTS and LTS layers.

Abstract: There is disclosed an assembly for carrying electrical current in a coil of a magnet. The assembly comprises a pre-formed housing of thermally and electrically conductive material (e.g. copper) which comprises a channel configured to retain HTS tape. A plurality of layers of HTS tape are fixed within the channel. The channel has at least one pre-formed curved section.

Abstract: A method of protecting a superconducting magnet from quenches, the superconducting magnet having at least one primary coil comprising high temperature superconductor, HTS, material. A secondary HTS tape is provided, the secondary HTS tape being in proximity to and electrically insulated from the primary coil, and being configured to cease superconducting at a lower temperature than the primary coil during operation of the magnet. A loss of superconductivity in the secondary HTS tape is detected. In response to said detection, energy is dumped from the primary coil into an external resistive load.

Abstract: An efficient compact nuclear fusion reactor for use as a neutron source or energy source is described. The reactor comprises a toroidal plasma chamber and a plasma confinement system arranged to generate a magnetic field for confining a plasma in the chamber. The plasma confinement system is configured so that a major radius of the confined plasma is 1.5 m or less. The reactor is constructed using high temperature superconducting toroidal magnets, which may be operated at low temperature (77K or lower) to provide enhanced performance. The toroidal magnetic field can be increased to 5 T or more giving significant increases in fusion output, so that neutron output is very efficient and the reactor can produce a net output of energy.

Abstract: An efficient compact nuclear fusion reactor for use as a neutron source or energy source includes a toroidal plasma chamber and a plasma confinement system arranged to generate a magnetic field for confining a plasma in the chamber, where the plasma confinement system is configured so that a major radius of the confined plasma is 1.5 m or less and the toroidal magnetic field is operated 5 T or less and the plasma current is 5 MA or less, yet a-particles generated are confined in the plasma.