The MAST motional Stark effect diagnostic

Conway, N. J.; Bock, M. F. M. de; Michael, Clive; Walsh, Mike; Carolan, P. G.; Hawkes, N.; Rachlew, Elisabeth; McCone, J.; Shibaev, S.; Wearing, G.

doi:10.1063/1.3494254

Cited by 28 publications

(30 citation statements)

References 10 publications

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“…The resulting change in pitch angle according to (1) would thus be ∆γ m ≈ 3 • . At 2 ms time resolution the MAST MSE system is capable of resolving this expected change in γ m [11,12,13].…”

Section: Measuring J φ In the Plasma Edgementioning

confidence: 99%

Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

Bock

Citrin

Saarelma

et al. 2012

Plasma Phys. Control. Fusion

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Edge Localized Modes (ELMs), that are present in most tokamak H-(high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is typically expressed in terms of the pressure gradient ∇p in the edge and the edge current density j φ . Both ∇p and j φ are usually derived from profiles fitted to the measured edge density and temperature profiles, where for the calculation of j φ neoclassical theory is used. This paper presents direct measurements of the magnetic pitch angle γ m evolution in the edge and the derived j φ . On the one hand these provide a method to validate the j φ as derived with neoclassical theory. On the other hand they open up the possibility to find a complete, self-consistent set of edge profiles, that fit both density, temperature and γ m measurements, hence allowing for a more accurate stability analysis.

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Section: Measuring J φ In the Plasma Edgementioning

confidence: 99%

Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

Bock

Citrin

Saarelma

et al. 2012

Plasma Phys. Control. Fusion

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“…The data shown in Figures 5 and 6 are based on measured data from the MAST MSE diagnostic. 5 Second, the determination of γ needs "signed" amplitudes. If not (4) would only be able to return γ between 0 and π /2, whereas γ does change sign when crossing the magnetic axis.…”

Section: Real-time Algorithmmentioning

confidence: 99%

Real-time MSE measurements for current profile control on KSTAR

Bock

Aussems

Huijgen

et al. 2012

Review of Scientific Instruments

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To step up from current day fusion experiments to power producing fusion reactors, it is necessary to control long pulse, burning plasmas. Stability and confinement properties of tokamak fusion reactors are determined by the current or q profile. In order to control the q profile, it is necessary to measure it in real-time. A real-time motional Stark effect diagnostic is being developed at Korean Superconducting Tokamak for Advanced Research for this purpose. This paper focuses on 3 topics important for real-time measurements: minimize the use of ad hoc parameters, minimize external influences and a robust and fast analysis algorithm. Specifically, we have looked into extracting the retardance of the photo-elastic modulators from the signal itself, minimizing the influence of overlapping beam spectra by optimizing the optical filter design and a multi-channel, multiharmonic phase locking algorithm.

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“…The magnetic probes outside the plasma are used to the magnetic island studies [9] , but it is difficult in the case of weak intensity or non-circular plasmas. Besides, the mode location needs to be measured with other diagnostics such as motional Stark effect (MSE) polarimeter [10,11] . By the soft X-ray detector arrays, 2-D magnetic island geometry can be reconstructed [12∼15] .…”

Section: Introductionmentioning

confidence: 99%

Measurement of Magnetic Island Width by Multi-Channel ECE Radiometer on HT-7 Tokamak

Han¹,

Ling²,

Gao³

et al. 2013

Plasma Sci. Technol.

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A 16-channel electron cyclotron emission (ECE) radiometer has been employed to observe the (m, n) = (2, 1) magnetic island structure on HT-7 tokamak, where m and n represent the poloidal and toroidal mode number respectively. The results indicate that the island width is about 7 cm when the magnetic island is saturated during the m/n = 2/1 mode. The location of resonance surface can be determined by plotting the contour of ECE relative fluctuation. This method could be applied to the HT-7 and EAST campaigns in the future for the research of neoclassical tearing modes (NTMs).

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The MAST motional Stark effect diagnostic

Cited by 28 publications

References 10 publications

Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

Measurements of the edge current evolution and comparison with neoclassical calculations during MAST H-modes using motional Stark effect

Real-time MSE measurements for current profile control on KSTAR

Measurement of Magnetic Island Width by Multi-Channel ECE Radiometer on HT-7 Tokamak

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