534 research outputs found
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Practical beta limit in ITER-shaped discharges in DIII-D and its increase by higher collisionality
The maximum beta which can be sustained for a long pulse in ITER-shaped plasmas in DIII-D with q{sub 95} {approx_gt} 3, ELMs, and sawteeth is found to be limited by resistive tearing modes, particularly m/n = 3/2 and 2/1. At low collisionality comparable to that which will occur in ITER, the beta limit is a factor of two below the usually expected n = {infinity} ballooning and n = 1 kink ideal limits
Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER
13MW of electron cyclotron current drive (ECCD) power deposited inside the q
= 1 surface is likely to reduce the sawtooth period in ITER baseline scenario
below the level empirically predicted to trigger neo-classical tearing modes
(NTMs). However, since the ECCD control scheme is solely predicated upon
changing the local magnetic shear, it is prudent to plan to use a complementary
scheme which directly decreases the potential energy of the kink mode in order
to reduce the sawtooth period. In the event that the natural sawtooth period is
longer than expected, due to enhanced alpha particle stabilisation for
instance, this ancillary sawtooth control can be provided from > 10MW of ion
cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1
surface. Both ECCD and ICRH control schemes would benefit greatly from active
feedback of the deposition with respect to the rational surface. If the q = 1
surface can be maintained closer to the magnetic axis, the efficacy of ECCD and
ICRH schemes significantly increases, the negative effect on the fusion gain is
reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be
considered for sawtooth control. Consequently, schemes to reduce the q = 1
radius are highly desirable, such as early heating to delay the current
penetration and, of course, active sawtooth destabilisation to mediate small
frequent sawteeth and retain a small q = 1 radius.Comment: 29 pages, 16 figure
Heating Titan's upper atmosphere
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95339/1/jgra19338.pd
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Measurement of the Resistive Wall Mode Stability in a Rotating Plasma Using Active MHD Spectroscopy
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Modeling of Feedback and Rotation Stabilization of the Resistive Wall Mode in Tokamaks
Simulating the one‐dimensional structure of Titan's upper atmosphere: 2. Alternative scenarios for methane escape
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94984/1/jgre2821.pd
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