Page 207 - Fundamentals of Magnetic Thermonuclear Reactor Design

Vacuum and Tritium System Chapter | 6 189

TABLE 6.1 Methods for Controlling Plasma Impurities
Key strengths and
Physical methods Design/Technical solutions weaknesses
Reduction of the flow Poloidal magnetic divertor Heavy impact on the
of ions bombarding magnetic configuration,
the wall using a which, however, keeps
special magnetic being axis-symmetric;
configuration at structural complexity,
the plasma edge the divertor plates’ high
and moving the power density.
ion recombination Bundle divertor Strong local magnetic
area outside the field perturbation;
plasma (the magnetic complexity, weak
divertor, Fig. 6.2). diverting effect.
Toroidal magnetic divertor Strong local magnetic
field perturbation; the
divertor plates’ high
power density.
Localisation of the Open-end pump limiter Structural simplicity;
ion recombination Closed pump limiter limiter’s high power
area in the plasma density and strict
boundary region materials requirements;
and its overlap with Structural simplicity;
the pumping area limiter’s very high-
(the pump limiter; power density and
Fig. 6.3).) materials requirements.
Reduction of Programmable introduction of Operational and
the particles gas in the boundary region structural simplicity;
bombardment power greater gas loads on the
through cold gas pumping system.
injection (the ‘gas
blanket’)
Reduction of Plasma current profile Operational and
the particles management structural complexity
bombardment
power translating
into sputtering rate
reduction
Sputtering rate Wall surface shaping, use of Inferior cooling
reduction through porous materials conditions and larger
condensation of a wall surface area;
portion of sputtered higher desorption flows
atoms (the ‘cell wall’
structure)

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