L. Carbajal R. O. Dendy S. C. Chapman J.W. S. Cook
Ion cyclotron emission (ICE) offers a unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity PICE scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, na=ni, of…
Preprint PublishedS.C. Chapman R.O. Dendy P.T. Lang N.W. Watkins F.A. Calderon
We focus on JET plasmas in which ELMs are triggered by pellets in the presence of ELMs which occur naturally. We perform direct time domain analysis of signals from fast radial field coils and toroidal full flux azimuthal loops. These toroidally integrating signals provide simultaneous high time resolution measurements of global plasma dynamics and…
Preprint PublishedJ. W. S. Cook R.O. Dendy S.C. Chapman
A fast Alfven wave with a finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer midplane plasma, where a population inversion of the energy distribution of fusion-born ions is …
Preprint PublishedW. N. Lai S. C. Chapman R. O. Dendy
The kinetic evolution in velocity space of a minority suprathermal electron population that is undergoing the anomalous Doppler instability (ADI) is investigated using the results from fully nonlinear numerical simulations that self-consistently evolve particles and fields in a plasma. Electron trajectories in phase space during different stages of…
Preprint PublishedH. Zhu R.O. Dendy S.C. Chapman S. Inagaki
It is known that rapid edge cooling of magnetically confined plasmas can trigger heat pulses that propagate rapidly inward. These can result in large excursion, either positive or negative, in the electron temperature at the core. A set of particularly detailed measurements was obtained in Large Helical Device(LHD) plasmas [S. Inagaki et al, Plasma…
Preprint PublishedL. Carbajal S. C. Chapman R. O. Dendy N. W. Watkins J. W. S. Cook
Preferential ion heating in the solar wind, observed as the occurrence of an ion beam which drifts along the background magnetic field with a velocity close to the local Alfven speed, is still an open problem. Several mechanisms have been identified that might work together in the solar wind to drive the observed ion heating. These mechanisms resul…
PreprintR.O. Dendy K.G. McClements
Ion cyclotron emission (ICE) was the first collective radiative instability, driven by confined fusion-born ions, observed from deuterium-tritium plasmas in JET and TFTR. ICE comprises strongly suprathermal emission, which has spectral peaks at multiple ion cyclotron harmonic frequencies as evaluated at the outer mid-plane edge of tokamak plasmas. …
Preprint PublishedK.G. McClements R. D’Inca R.O. Dendy L. Carbajal S.C. Chapman J.W.S. Cook R.W. Harvey W.W. Heidbrink S.D. Pinches
The detection of fast particle-driven waves in the ion cyclotron frequency range (ion cyclotron emission or ICE) could provide a passive, non-invasive diagnostic of confined and escaping fast particles (fusion a-particles and beam ions) in ITER, and would be compatible with the high radiation environment of deuterium–tritium plasmas in that devic…
Preprint PublishedS. J. Freethy K. G. McClements S. C. Chapman R. O. Dendy W. N. Lai S. J. P. Pamela V. F. Shevchenko R. G. L. Vann
Recent measurements of microwave and x-ray emission during edge localized mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should b…
Preprint PublishedS. C. Chapman R. O. Dendy T. N. Todd N. W. Watkins F. A. Calderon J. Morris JET Contributors
A global signature of the build-up to an intrinsic edge localized mode (ELM) is found in the temporal analytic phase of signals measured in full flux azimuthal loops in the divertor region of JET. Toroidally integrating, full flux loop signals provide a global measurement proportional to the voltage induced by changes in poloidal magnetic flux; the…
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