A tokamak fusion reactor. The tokamak fusion reactor comprises a toroidal plasma chamber and a plasma confinement system arranged to generate a magnetic field for confining a plasma in the plasma chamber. The plasma confinement system comprises toroidal field magnets, which generate a magnetic field, B.sub.T0, in the centre of the plasma. The toroidal field magnets are configured such that, in use, the magnetic field, on conductor of the toroidal field magnets is at least 20 Tesla. The plasma confinement system is configured such that, in use, the plasma has: an aspect ratio, A, of 2 or less; an elongation, K, of at least 2; a major radius R.sub.0 of 3.5 meters or less; a normalised beta of at least 3; an engineering safety factor, q.sub.eng, of at least 2.0; wherein the engineering safety factor q.sub.eng is defined as: g.sub.eng=5 B.sub.T0R.sub.0K/A.sup.2I.sub.P where I.sub.p is the plasma current; a ratio of the fusion gain, Q.sub.fus to the fusion power, P.sub.fus, greater than 0.03 MW.sup.−1 at fusion power, P.sub.fus, less than 500 MW.

A superconducting magnet for producing part of a substantially toroidal field in a device is described. The magnet comprises: a set of conductors comprising one or more first conductors (31f) and one or more second conductors (32f), and a set of joints (33). Each of the joints (33) connects a region of a first conductor (31f) with a region of a second conductor (32f) to form a series of alternating first and second conductors corresponding to at least part of a winding of the magnet. Each of the joints (33) is positioned away from a midplane of the toroidal field. The joints (33) are positioned on alternating sides of the midplane. Each first conductor (3 If) passes through the midplane at a smaller distance from an axis of rotation of the toroidal field than does each second conductor (32f). Each of the regions is elongate and extends in a direction at least partly away from the midplane.

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.

Described are concepts directed toward systems, structures and techniques to create low-resistance, high current capacity, demountable solder joint connections. Such systems, structures and techniques may be used to simultaneously create low-resistance, high current capacity, demountable solder joint connections at multiple locations between no insulation (NI) superconductors and in particular between NI high temperature superconductors (HTS) such as may be used in NI-HTS magnets.

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.

The present invention discloses a simulation method for three-dimensional full-space plasma response in EAST tokamak. In numerical simulation of plasma response in an EAST tokamak device, firstly, single frequency waves with different frequencies and amplitudes are selected according to experiment needs, to design waveforms of an external perturbation current field; then selected single frequency current field waveforms are respectively used as driving terms to solve magnetohydrodynamic equations containing an external driving current field to solve the distribution of the single frequency magnetic response signals in a three-dimensional full space; and finally, multiple groups of the single frequency magnetic response signals are superimposed and converted into a time domain space to obtain the three-dimensional full-space distribution of plasma magnetic response signals at any time. The present invention realizes the corresponding full-space distribution of plasma at any time in the process of simulating EAST tokamak discharge experiments, and makes up for the deficiency that the distribution of full-space magnetic signals cannot be obtained by experimental measurement. The present invention has accurate simulation results and strong practicality, and is a stable and efficient numerical simulation method.

Examples of a system for generating and confining a compact toroid are disclosed. The system comprises a plasma generator for generating magnetized plasma, a flux conserver for receiving the compact toroid, a power source for providing current pulse and a controller for actively controlling a current profile of the pulse to keep plasma's q-profile within pre-determined range. Examples of methods of controlling a magnetic lifetime of a magnetized plasma by controlling a current profile of the current pulse are disclosed.

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.

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.

A cable for carrying electrical current in a coil of a magnet. The magnet comprises an HTS transport tape and a shunt assembly comprising two or more HTS shunt tapes arranged side-by-side across a face of the transport tape. Each of the transport and shunt tapes comprises a substrate layer and an HTS layer of high temperature superconductor (HTS) material, the layers of the shunt tapes extending parallel to the layers of the transport tape.