Abstract: A cable for carrying electrical current in a coil of a magnet. The cable comprises a stack of tape assemblies. Each tape assembly has a length and a width, such that the length is much larger than the width, and each tape assembly comprises an HTS layer of anisotropic high temperature superconductor. HTS material, wherein a c-axis of the HTS layer is at a non-zero angle to a vector perpendicular to the plane of the HTS layer. The tape assemblies are stacked as a series of pairs, each pair comprising first and second HTS tape assemblies and a copper layer therebetween. The tape assemblies in each pair are arranged such that the c-axis of the HTS layer of the first HTS tape assembly of each pair have reflective symmetry to the c-axis of the HTS layer of the second HTS tape assembly of each pair about a plane which is parallel to and equidistant from each HTS layer.

Abstract: A High Temperature Superconductor, HTS, magnet comprising a coil formed of nested concentric windings. Each winding comprises HTS material. The HTS magnet further comprises a conductor element comprising an electrical contact surface through which to supply electric current to a portion of at least one of the windings. The surface provides electrical contact between the conductor element and an axial edge of the coil substantially around the path of the at least one of the windings.

Abstract: A high temperature superconducting, HTS, current lead comprising an HTS cable including a plurality of HTS tapes, a braided sleeve around the HTS cable, and a stabiliser material impregnating the HTS cable and the braided sleeve, the stabiliser material having a melting point above 290K and below a thermal degradation temperature of the HTS tapes.

Abstract: A method of manufacturing an HTS coil is provided. The method comprises winding an ITS coil cable to produce a coil having a plurality of turns. During winding of a turn of the coil, one or more HTS shunt cables are placed adjacent to the previous turn of the coil along a first arc of the coil, and then the turn is wound such that the HTS shunt cable is sandwiched between the turn and the previous turn of the coil such that current can be shared between the HTS shunt cable and the HTS coil cable.

Abstract: A metal sealing ring (1) for forming a metal-to-metal seal between two opposing metal surfaces. The metal sealing ring (1) comprises a tubular metal body (3) and an inlet tube (7) extending from the body (3) for introducing an internal pressure into the body (3). The body is adapted to deform under the internal pressure against each of the opposing metal surfaces to form the seal (1).

Abstract: A method of controlling a plasma in a nuclear fusion reactor. The nuclear fusion reactor comprises sensors and plasma control inputs. An initial control model is provided, relating readings of at least a subset of the sensors to control of the plasma control inputs. A control loop is performed, comprising: operating the plasma control inputs in dependence upon the sensors according to the control model; determining correlations between readings of each of the sensors, and/or between readings of the sensors and states of the plasma control inputs; and adjusting the control model based on the determined correlations.

Abstract: A breeder blanket for generating tritium using neutrons produced by nuclear fusion of deuterium and/or tritium within a plasma confined within a fusion reactor. The breeder blanket comprises: a plasma-facing first wall; a breeder layer comprising lithium containing material for generating tritium from the neutrons; and neutron moderator material comprising metal hydride and/or deuteride arranged between the first wall and the lithium-containing material.

Abstract: A superconducting magnet comprising: a field coil comprising high temperature superconducting material and having a joint; a bypass resistance comprising a non-superconducting conductive material, wherein the bypass resistance is electrically connected to the field coil on both sides of the joint; wherein the joint is openable to break the field coil such that current flowing in the superconductor flows though the bypass resistance in order to dump energy from the field coil, and wherein the superconducting magnet is configured to open the joint in response to detection of a quench in the magnet.

Abstract: A method of detecting pre-quench conditions in a superconducting magnet comprising an HTS field coil. The field coil comprises a plurality of turns comprising HTS material and metallic stabilizer; and conductive material connecting the turns such that current can be shared radially between turns via the conductive material. Strain is monitored for the HTS field coil and/or support structures of the HTS field coil. The monitored strain is compared to an expected strain during normal operation of the magnet. In response to the comparison, it is determined whether the field coil is in pre-quench conditions. A similar method is provided where the magnetic field of the HTS field coil is monitored to detect pre-quench conditions, instead of the strain.

Abstract: A method of controlling a plasma in a nuclear fusion reactor. The nuclear fusion reactor comprises sensors and plasma control inputs. An initial control model is provided, relating readings of at least a subset of the sensors to control of the plasma control inputs. A control loop is performed, comprising: operating the plasma control inputs in dependence upon the sensors according to the control model; determining correlations between readings of each of the sensors, and/or between readings of the sensors and states of the plasma control inputs; and adjusting the control model based on the determined correlations.

Abstract: A segment of a field coil, a toroidal field coil, and a method of manufacturing is provided. The segment of a field coil is for use in a superconducting electromagnet. The segment includes an assembly for carrying electrical current in a coil of a magnet. The assembly includes a pre-formed housing comprising a channel configured to retain high temperature superconductor (HTS) tape, the channel including at least one pre-formed curved section. The assembly further includes a plurality of layers of HTS tape fixed within the channel. Wherein the pre-formed curved section has a radius of curvature which is less than a total thickness of the layers of HTS tape in that section divided by twice a maximum permitted strain of the HTS tape.

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: A device comprising a high temperature superconductor, HTS, circuit; wherein the HTS circuit comprises: a quenchable section comprising HTS material and connected in series to other elements of the HTS circuit, the HTS material comprising a stack of HTS takes comprising at least one HTS tape; the device further comprising: a quenching system configured to quench the HTS material in the quenchable section; a quench protection system configured to detect temperature rises in the HTS circuit and, in response to detection of a temperature rise, cause the quenching system to quench the superconducting material in the quenchable section in order to dump stored magnetic energy from the HTS circuit into the quenchable section; wherein the HTS circuit is configured such that, when in use, the magnetic field on the or each HTS tape is substantially parallel to a a-b plane of the HTS tape, and the quenching system is configured to quench the HTS material by producing an additional magnetic field along the length of the

Abstract: A method of operating a nuclear fusion device. The nuclear fusion device comprises a toroidal plasma chamber and has poloidal field coils configured to form a plasma within the plasma chamber by one of merging compression and double null merging. A varying current is provided to the poloidal field coils. The varying current comprises a plurality of pulses. Each pulse comprises a plasma formation period having a rate of change of current which is opposite in sign to the current; and a merging period following the plasma formation period and having a current sufficiently low in magnitude as to allow plasmas within the chamber to merge into a single plasma. The current during the plasma formation period is varied such that the energy density of the single plasma immediately after merging is sufficient for fusion to occur.

Abstract: A poloidal field coil assembly for use in a tokamak. The poloidal field coil assembly comprises inner and outer poloidal field coils and a controller. The inner poloidal field coil is configured for installation inside a toroidal field coil of the tokamak. The outer poloidal field coil is configured for installation outside the toroidal field coil. The controller is configured to cause current to be supplied to the inner and outer poloidal field coils such that the combined magnetic field produced by the inner and outer poloidal field coils has a null at the toroidal field coil.

Abstract: A partially insulating layer for use in an HTS magnet coil. The partially insulating layer comprises an insulating body 401 having within it a set of linking tracks and a set of pickup tracks. Each linking track is electrically conductive and is electrically connected to first and second surfaces of the partially insulating layer, in order to provide an electrical path between said first and second surfaces. Each pickup track is electrically conductive and is inductively coupled to a respective linking track, and electrically isolated from the first and second surfaces. Each of the pickup tracks is configured for connection to a current measuring device in order to measure a current induced in the pickup track by a change in current flowing in the respective linking track.

Abstract: A tokamak plasma vessel. The tokamak plasma vessel comprises a toroidal plasma chamber, a plurality of poloidal field coils, an upper divertor assembly, and a lower divertor assembly. The plurality of poloidal field coils are configured to provide a poloidal magnetic field having a substantially symmetric plasma core and an upper and lower null, such that ions in a scrape off lay outside the plasma core are directed by the magnetic field past one of the upper and lower nulls to divertor surfaces of the respective upper and lower divertor assembly. Each of the upper and lower divertor assembly comprises a liquid metal inlet and a liquid metal outlet located below the liquid metal inlet. Each of the upper and lower divertor assembly is configured such that in use liquid metal flows from the liquid metal inlet to the liquid metal outlet over at least one divertor surface of the divertor assembly.

Abstract: A method of manufacturing an HTS coil is provided. The method comprises winding an HTS coil cable to produce a coil having a plurality of turns. During winding of a turn of the coil, one or more HTS shunt cables are placed adjacent to the previous turn of the coil along a first arc of the coil, and then the turn is wound such that the HTS shunt cable is sandwiched between the turn and the previous turn of the coil such that current can be shared between the HTS shunt cable and the HTS coil cable.

Abstract: There is described a magnet assembly comprising a superconducting coil, a cryogenic system, a DC voltage source, an SMPS, current leads, and a controller. The cryogenic system comprises a cryostat and is configured to maintain the superconducting coil at an operating temperature below the critical temperature of the superconductor. The DC voltage is source located outside the cryostat. The SMPS is located inside the cryostat and configured to supply power from the DC voltage source to the superconducting coil. The SMPS comprises a voltage step-down transformer having a primary and a secondary winding. The current leads connect the DC voltage source to the SMPS. The controller is configured to cause the SMPS to supply a first amount of power to the magnet in order to ramp up the magnet to operating current, and a second amount of power to the magnet during steady state operation of the magnet, wherein the first amount of power is greater than the second amount of power.

Abstract: A toroidal field coil comprising a central column, a plurality of return limbs, a quench protection system, and a cooling system. The central column comprises IITS material. Each return limb comprises a quenchable section, two IITS sections, and a quenching 5 system. The quenchable section comprises superconducting material, and is configured to contribute towards a magnetic field of the toroidal field coil. The IITS sections comprise IITS material. The IITS sections electrically connect the quenchable section to the central column and are in series with the central column and the quenchable section. The quenching system is associated with the quenchable section 10 and configured to quench the quenchable section.