Obtaining gigaflop performance from particle simulation of plasmas

In the numerical simulation of plasma phenomena there are two fundamental approaches that are generally followed. In the continuum approach one models the evolution of the fluid moment equations derived from the appropriate Boltzmann equation of the plasma. Alternatively, in the particle approach a large group of simulated charged particles are moved according to the self-consistent electromagnetic fields which partly depend on the charge and current densities of these same particles. Although the particle simulation method has been traditionally the more expensive of the two, it is much more capable of giving adequate account of many important kinetic phenomena. With the advent of the vector multiprocessor supercomputers, such as the Cray-2 or Cray Y-MP, we have learned to adapt particle simulation codes to exploit the parallel features of these machines. Yet, in spite of such developments, the particle simulation codes have remained much slower than the maximum machine speeds. We have investigated new techniques that further optimize these methods to bring the speeds of these particle simulations into the gigaflop range. Recent progress in this area suggests that the use of particle simulation methods will become competitive with the alternative fluid models especially when it is realized that gigaflop performance makes them much more affordable. 2 refs., 3 tabs

Nova LMC (Large Magellanic Cloud) 1990 No. 1: The first extragalactic neon Nova

IUE observations of Nova LMC 1990 No. 1, the first neon (or ONeMg) nova observed outside the Galaxy, were obtained from 17 January 1990 through March 1990, with especially dense coverage during the first 25 days of the outburst. (The neon'' nova categorization is based on the detection of forbidden Ne III-V lines in optical spectra; the ultraviolet neon lines were not detected.) During the first 30 days of the outburst, the radiative losses were dominated by the N V {lambda}1240 and C IV {lambda}1550 lines. The maximum ejection velocity was approximately 8000 km/s, based on the blue absorption edge of the C IV P-Cygni profile. Early in the outburst of Nova LMC 1990 No. 1 the UV luminosity alone was {approximately} 3 {times} 10{sup 38} erg/sec, implying that the bolometric luminosity was well in excess of the Eddington luminosity for a one solar mass object. 9 refs., 4 figs

High-energy gamma-radiation from Geminga observed by EGRET

Available from TIB Hannover: RN 9303(265) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman