H. Weisen A. C. C. Sips C. D. Challis L.-G. Eriksson S. E. Sharapov P. Batistoni L. D. Horton K.-D. Zastrow EFDA-JET Contributors
After the first high power D-T experiment in JET in 1997 (DTE1), when JET was equipped with Carbon PFC’s, a proposed second high power (up to ~40MW) D-T campaign (DTE2) in the current Be/W vessel will address essential operational, technical, diagnostics and scientific issues in support of ITER. These experiments are proposed to minimize the risk…
PublishedS.E. Sharapov B. Alper H.L. Berk D.N. Borba B.N. Breizman C.D. Challis I.G.J. Classen E.M. Edlund J. Eriksson A. Fasoli E.D. Fredrickson Et Al
Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfven instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomen…
PublishedM. Turnyanskiy C. D. Challis R. J. Akers M. Cecconello D. L. Keeling A. Kirk R. Lake S. D. Pinches S. Sangaroon I. Wodniak
Previous experiments on MAST and other tokamaks have indicated that the level of fast ion redistribution can exceed that expected from classical diffusion and that this level increases with beam power. In this paper we present a quantification of this effect in MAST plasmas using a recently commissioned scanning neutron camera. The observed fast io…
PublishedP. Mantica C. Angioni C. Challis G. Colyer L. Frassinetti N. Hawkes T. Johnson M. Tsalas P. C. Devries J. Weiland B. Baiocchi M. N. A. Beurskens A. C. A. Figueiredo C. Giroud J. Hobirk E. Joffrin E. Lerche V. Naulin A. G. Peeters A. Sal
New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [ Phys. Rev. Lett. 102, 175002 (2009) ] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implications for the understanding of improved ion core con…
PublishedYu. F. Baranov C. D. Challis A. Ekedahl M. Goniche K. Kirov et al.
Mechanisms of arc formation have been analyzed and the critical electric fields for the multipactor effect calculated, compared to the experimental values and found to be within the normal operational space of the LH system on JET. It has been shown that the characteristic electron energy (20-1000)eV for the highest multipactor resonances (N=4-9) a…
PublishedH Meyer R J Akers F Alladio L C Appel K B Axon N Ben Ayed P Boerner R J Buttery P G Carolan D Ciric C D Challis I T Chapman Et Al
Several improvements to the MAST plant and diagnostics have facilitated new studies advancing the physics basis for ITER and DEMO, as well as for future spherical tokamaks. Using the increased heating capabilities PNBI ≤ 3.8 MWH-mode at Ip = 1.2 MA was accessed showing that the energy confinement on MAST scales more weakly with Ip and more strong…
PublishedC. Gormezano C. D. Challis E. Joffrin X. Litaudon A. C. C. Sips
A review of the development of advanced tokamak scenarios at the Joint European Torus (JET) is presented. It has been established that the current profile plays an important role in these regimes, and the presentation of the experimental achievement has been organized with this in mind. The main achievements are discussed: from high beta plasmas st…
PublishedM. F. F. Nave H. R. Koslowski S. Coda J. Graves M. Brix R. Buttery C. Challis C. Giroud M. Stamp P. De Vries Jet-Feda Contributors
During a recent reversed toroidal field (B T) campaign at the Joint European Torus (JET), experiments were performed to investigate the effect on sawteeth of neutral beam injection (NBI)-driven toroidal plasma rotation counter to the direction of the toroidal plasma current and B T . A power scan at constant density has permitted analytical continu…
PublishedN. C. Hawkes B. C. Stratton T. Tala C. D. Challis G. Conway R. Deangelis C. Giroud J. Hobirk E. Joffrin P. Lomas P. Lotte J. Mailloux D. Mazon E. Rachlew S. Reyes-Cortes E. Solano K-D. Zastrow
Simultaneous current ramping and application of lower hybrid heating and current drive (LHCD) have produced a region with zero current density within measurement errors in the core of JET tokamak optimized shear discharges. The reduction of core current density is consistent with a simple physical explanation and numerical simulations of radial cur…
PublishedN. C. Hawkes B. C. Stratton T. Tala C. D. Challis G. Conway R. Deangelis C. Giroud J. Hobirk E. Joffrin P. Lomas P. Lotte J. Mailloux D. Mazon E. Rachlew S. Reyes-Cortes E. Solano K-D. Zastrow
Modern charge-coupled-device (CCD) detectors can achieve peak quantum efficiencies of 90%, compared with less than 10% for the photocathode of an electron multiplier. We report on laboratory tests of examples of these two detector technologies to evaluate their relative performance for precision Doppler spectroscopy of laboratory plasmas. The tests…
Published