Term Definition
B magnetic field
BA Broader Approach
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 centre of mass.
base programmes The fusion programmes of the BA participants, in particular the physics programmes.
baseline The set of documents making up, or appropriate to, the current design.
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.
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.
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.
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.
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  Updated 13 February, 2017