| Term | Definition |
|---|---|
| B | magnetic field |
| baffle elements | Limit the conductance between the divertor and the main chamber. |
| ballooning instabilities | Magnetohydrodynamic instabilities caused by the pressure gradient of the plasma. |
| barycenter | The center of mass. |
| base programmes | The fusion programmes of the ITER participants, in particular the physics programmes. |
| baseline | With respect to ITER, a set of documents describing the design which will be (as far as possible) fully self consistent at a given (future) time (i.e. at a project milestone). In ITER terminology, the set of documents making up, or appropriate to, the current design data. ITER therefore uses the concept of a “rolling baseline”. |
| beam emission spectroscopy | BES, plasma diagnostics using light emission from a low energy neutral beam . |
| beamlines | The flight tube connecting the neutral beam box to the plasma torus. Sometimes, colloquially, the complete beam system including the beam box. |
| beta limit | Maximum plasma pressure that can be contained stably by the magnetic pressure generated by the confinement field. |
| beyond-design-basis accidents |
Postulated event sequences that are more severe than accident conditions and considered outside of the design basis. |
| BHP | biological hazard potential |
| bioshield | A thick wall of concrete surrounding the main tokamak cryostat and designed to absorb the bulk of the remaining neutron radiation from the plasma. This shields the region outside so that it can be accessed, at maximum a couple of weeks after shutdown, for major hands-on repairs. |
| blanket | In fusion, a region surrounding a fusion reactor plasma within which the fusion neutrons are slowed down, heat is transferred to a primary coolant, and tritium is bred from lithium. |
| blanket module | In ITER, the blanket is subdvided in modules to allow it to be relatively easily replaced through equatorial access ports. The mass of each module is in the range of 5t. The module consists of a backing shield or breeding region, on which is mounted a first wall panel to face the plasma. |
| blanket-shield | The first component facing the plasma; it removes heat and protects the vacuum vessel and magnets from radiation damage. |
| Bohm diffusion | A rapid loss of plasma across magnetic field lines caused by microinstabilities. Theory formulated by the physicist David Bohm. |
| bolometer | An instrument that measures the energy of electromagnetic radiation in certain wavelength regions by utilizing the change in resistance of a thin conductor caused by the heating effect of the radiation. Also known as thermal detector. |
| bootstrap current | Plasma current induced by trapped particles in a tokamak /stellarator. |
| BOP | Balance of Plant in ITER usually refers to complete plant systems located outside the Tokamak Building |
| borated concrete | A form of concrete to which extra Boron has been added. Boron is particularly good at absorbing neutrons. This concrete may be used in the ITER bioshield. |
| boronization | A technique for wall conditioning using boron to reduce the effective impurity in a tokamak . |
| breakeven | The point at which the fusion power produced by a reacting plasma equals the input power needed to sustain the plasma's high temperature. To produce net power in a fusion reactor, according to the "Lawson criterion," in a plasma of about 70 million degrees centigrade with a density of 1014 particles per cubic centimeter, the plasma must be contained for at least one second. |
| breeding blanket | A tokamak structure where tritium is bred by neutron capture in lithium. |
| breeding technologies | A number of different combinations of tritium breeding material, neutron multiplier, structural material, and coolant will be tried out on ITER to determine the best combination for tritium and power production. Each one of these solutions is referred to as a “breeding technology”. |
| bremsstrahlung | Radiation emitted as a result of deflection (e.g. through near collisions) of rapidly moving charged particles. |
| bumper limiters | In tokamaks, any structures inside the vacuum vessel which protrude into the plasma space to intercept plasma which would otherwise strike other plasma facing components. |
| burn | The period of roughly constant and maximum fusion power during the plasma pulse. |
| burning plasma | A plasma significantly heated by alpha particles from internal fusion reactions. Significantly this usually means the alpha particle power is as large as the externally applied power. |
| business confidential information | Information containing know-how, trade secrets, or technical, commercial or financial information, which: 1) has been held in confidence by its owner; 2) is not generally known or available from other sources; 3) has not been made available by its owner to other parties without an obligation concerning its confidentiality, and 4) is not available to the receiving party without obligations concerning its confidentiality. |
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