Overview of MAST Neutral Beam System performance

Homfray, D.; Ćirić, D.; Dunkley, V.; King, R.; Payne, Don M.; Simmonds, M.; Stevens, Brian; Stevenson, P. D.; Tame, Chris R.; Warder, S.; Whitehead, A.; Young, D.

doi:10.1109/fusion.2009.5226423

Cited by 9 publications

(8 citation statements)

References 5 publications

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“…The experiment was run twice, once at low density and again at high density allowing a comparison to be made between similar plasmas with varying collisionality and temperature. Due to constraints on available machine time, a newly commissioned function of the MAST NBI system [51] was utilised which allowed four short beam 'blips' to be fired with start-times and duration that could be specified to within ± 1 ms. Obviously it is desirable that such blips, intended for diagnostic measurements only, be kept as short as possible so as to perturb the plasma as little as possible. The MSE system operated at 100 Hz and required 5 ms integration time to produce a useable signal.…”

Section: Mast Stationary Statementioning

confidence: 99%

Test of electrical resistivity and current diffusion modelling on MAST and JET

et al. 2017

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Experiments have been carried out on the MAST and JET tokamaks intended to compare the electrical resistivity of the plasma with theoretical formulations. The tests consist of obtaining motional stark effect (MSE) measurements in MHD-free plasmas during plasma current ramp-up (JET and MAST), ramp-down (MAST) and in stationary state (JET and MAST). Simulations of these plasmas are then performed in which the current profile evolution is calculated according to the poloidal field diffusion equation (PFDE) with classical or neoclassical resistivity. Synthetic MSE data are produced in the simulations for direct comparison with the experimental data. It is found that the toroidal current profile evolution modelled using neoclassical resistivity did not match the experimental observations on either device during current ramp-up or ramp-down as concluded from comparison of experimental and synthetic MSE profiles. In these phases, use of neoclassical resistivity in the modelling systematically overestimates the rate of current profile evolution. During the stationary state however, the modelled toroidal current profile matched experimental observations to a high degree of accuracy on both devices using neoclassical resistivity. Whilst no solution to the mismatch in the dynamic phases of the plasma is proposed, it is suggested that some physical process other than MHD which is not captured by the simple diffusive model of current profile evolution is responsible.

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Section: Mast Stationary Statementioning

confidence: 99%

Test of electrical resistivity and current diffusion modelling on MAST and JET

et al. 2017

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“…The current method of controlling MAST neutral beam is through a series of fast timer cards [1]. These cards are becoming obsolete, unsupported by the manufacturer and need to be replaced for the MAST Upgrade.…”

Section: Future Implementationmentioning

confidence: 99%

“…The MAST PINIs use a tetrode accelerator, operate in deuterium and use a filament driven discharge to produce up to 65 A of extracted beam current [1].…”

Section: Introductionmentioning

confidence: 99%

Real time neutral beam power control on MAST

Homfray

Benn

Ćirić

et al. 2011

Fusion Engineering and Design

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“…MAST presently has two identical Neutral Beam Injectors; the South and Southwest beamlines. These injectors are capable of extracting a deuterium ion beam of 65A at 75keV [6,7]. The resulting maximum neutral beam power transmitted into MAST is approximately 2.5MW from each injector.…”

Section: The Mast Neutral Beam Injectors and Pumping System 21 The Nmentioning

confidence: 99%

Control and calculation of the titanium sublimation pumping speed and re-ionisation in the MAST neutral beam injectors

McAdams¹

2015

Fusion Engineering and Design

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A high pumping speed is required in neutral beam injectors to minimise re-ionisation of the neutral beams. The neutral beam injectors on MAST use titanium sublimation pumps. These pumps do not have a constant pumping speed; their pumping speed depends on the gettering surface history and on both the integrated and applied gas load. In this paper we report a method of maintaining a constant pumping speed, through different evaporation schemes, suitable for operations of the MAST beamline for both short and relatively long beam pulses by measurement of the pressure in the beamline. In addition the MCNP code is then used to calculate the gas profile in the beamline by adjusting the input pumping speed to match the measured pressure. This allows the resulting gas profile to be used for calculation of the re-ionisation levels and an example is given.

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Overview of MAST Neutral Beam System performance

Cited by 9 publications

References 5 publications

Test of electrical resistivity and current diffusion modelling on MAST and JET

Test of electrical resistivity and current diffusion modelling on MAST and JET

Real time neutral beam power control on MAST

Control and calculation of the titanium sublimation pumping speed and re-ionisation in the MAST neutral beam injectors

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