P. Helander H. Smith T. Fülöp L.-G. Eriksson
The distribution function of suprathermal electrons in a slowly cooling plasma is calculated by an asymptotic expansion in the cooling rate divided by the collision frequency. Since the collision frequency decreases with increasing velocity, a high-energy tail forms in the electron distribution function as the bulk population cools down. Under cert…
PublishedG. J. Kramer S. E. Sharapov R. Nazikian N. N. Gorelenkov R.V. Budny
Experimental evidence is presented for the existence of the theoretically predicted odd toroidicity induced Alfve?n eigenmode (TAE) from the simultaneous appearance of odd and even TAEs in a normal shear discharge of the joint European torus. The modes are observed in low central magnetic shear plasmas created by injecting lower hybrid current driv…
PublishedS. Shiraiwa S. Ide S. Itoh O. Mitarai O. Naito T. Ozeki Y. Sakamoto T. Suzuki Y. Takase S. Tanaka T. Taniguchi M. Aramasu T. Fujita T. Fukuda X. Gao M. Gryaznevich K. Hanada E. Jotaki Y. Kamada T. Maekawa Y. Miura K. Nakamura T. Nish
A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This was accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, and the loop voltage supplied by the vertical field and shaping coils. The Ohmic heating (OH) solenoid was not used but a small inboard coil (part of the shaping…
PublishedN.C. Woolsey A.D. Ash D.M. Chambers C. Courtois R.O. Dendy R.A.D. Grundy K.G. McClements
Laboratory astro-plasma physics experiments are being designed to advance both our astrophysics and plasma physics knowledge. With current laser technology, target design and diagnostics, it is now possible to reproduce and measure the conditions of temperature and pressure usually met in extreme stellar environments. Coupled with scaled plasma phy…
PublishedK.J.H. Phillips J.A. Rainnie L. K. Harra J. Dubau F.P. Keenan N.J. Peacock
The inclusion of collisional rates for He-like Fe and Ca ions is discussed with reference to the analysis of solar flare Fe XXV and Ca XIX line emission, particularly from the Yohkoh Bragg Crystal Spectrometer (BCS). The new data are a slight improvement on calculations presently used in the BCS analysis software in that the discrepancy in the Fe X…
PublishedH. R.Wilson S. C. Cowley
Flux tubes confined in tokamaks are observed to erupt explosively in some plasma disruptions and edge localized modes. Similar eruptions occur in astrophysical plasmas, for example, in solar flares and magnetospheric substorms. A single unifying nonlinear evolution equation describing such behavior in both astrophysical and tokamak plasmas is deriv…
PublishedS. L. Dudarev A. A. Semenov C. H. Woo
We investigate the dynamics of nucleation and the growth of voids in an irradiated material in the presence of a spatially heterogeneous dislocation microstructure. We find that, due to the sensitivity of the void nucleation rate to the local vacancy supersaturation, voids nucleate and grow almost exclusively in the regions where the density of dis…
PublishedL.-G. Eriksson P. Helander F. Andersson D. Anderson M. Lisak
Self-consistent modeling of the evolution of the plasma current during disruptions in large tokamaks is presented, taking into account both the generation of runaway electrons and their backreaction on the electric field. It is found that the current profile changes dramatically, so that the postdisruption current carried by runaway electrons is mu…
PublishedN. J. Sircombe T. D. Arber R. O. Dendy
Direct numerical simulations of electron dynamics in externally driven electrostatic waves have been carried out using a relativistic two-fluid one-dimensional Vlasov–Poisson code. When the driver wave has sufficiently large amplitude, ion density holes ( cavitons ) form. The interaction between these cavitons and other incoming Langmuir waves gi…
Published