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2004
Both ruby laser ( 300 points ) and NdYAG laser ( 19 points ) Thomson scattering systems are used on MAST. Fast nonlinear optical switching shunts laser beams from the four 50 Hz NdYAG lasers to obtain coaxial plasma illumination. The technique allows for future expandability to many laser systems. The ruby laser system is used in parallel. A broadb…
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2004
The Mega Amp Spherical Torus ( MAST ) diagnostic needs are strongly influenced by physics goals that often require diagnostic integration and cross-mapping, especially in fine-scale investigations, such as transport barriers. Conversely, the unrivalled viewing access to the edge, scrape-off layer ( SOL ) and divertor regions, provided by the MAST o…
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2004
A curved crystal spectrometer in Johann configuration has been implemented on MAST to obtain values for electron temperature, ion temperature and toroidal velocity. The spectrometer is used to examine medium Z impurities in the soft x-ray region by utilising a Silicon ( 111 ) crystal, bent using a 4 pin bending jig, and a CCD detector sD t =8 ms d …
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2004
A bremsstrahlung diagnostic has been deployed on the Mega Ampere Spherical Tokamak ( MAST ) , with matrix viewing of the full plasma cross section in a narrow region of the continuum free of spectral lines. An uncooled CCD detector is used to provide 100 Hz 128 3 128 matrix viewing of the plasma emissivity which is spectrally selected using an inte…
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2004
Spectral imaging diagnostics that view the full plasma cross section are used on MAST with sensor resolutions and frame rates of up to 256 x 512 chords and 130 Hz, respectively. The incident and solid angles of filter illumination are fully controllable. Image splitting and spectral selection with separate filters are performed in the telecentric r…
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2004
This Letter provides information on the spatial and temporal structure of periodic eruptions observed in magnetically confined laboratory fusion plasmas, called edge-localized modes (ELMs), and highlights similarities with solar eruptions. Taken together, the observations presented in this Letter provide strong evidence for ELMs being associated wi…
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2004
Gyrokinetic microstability analyses, with and without electromagnetic effects, are presented for a spherical tokamak plasma equilibrium closely resembling that from a high confinement mode ( H mode ) discharge in the mega-ampere spherical tokamak ( MAST ) [ A. Sykes et al. , Nucl. Fusion 41 , 1423 ( 2001 )] . Electrostatic ion temperature gradient …
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2003
A dual laser Thomson scattering system is implemented in the Mega Amp Spherical Tokamak (MAST). The complementary features of each approach are exploited. One system is ideally suited to measuring detailed profile behavior across the plasma while the other is ideally suited though not exclusively to studying fast changing events and general charact…
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2003
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2003
The nature of intermittency, long observed in magnetic fusion devices, was revisited lately [G. Antar et al. , Phys. Rev. Lett. 87 , 065001 (2001)]. It was shown that intermittency is caused by large-scale events with high radial velocity reaching about 1/10th of the sound speed. These type of structures were named ‘‘avaloids.’’ In the pres…
Showing 281 - 290 of 302 UKAEA Paper Results