| Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.cosmos.ru/galeev/abs_eng/e120517.htm Дата изменения: Wed Apr 18 17:25:48 2012 Дата индексирования: Tue Oct 2 06:39:50 2012 Кодировка: Windows-1251 Поисковые слова: rainbow | 
| 
 | 
 | 
|     | "Stochastic
  Particle Acceleration and the Problem of Background Plasma Overheating" D.O. Chernyshov and
  V.A. Dogiel (P.N.Lebedev Institute of
  Physics) Abstract: The origin of hard X-ray (HXR)
  excess emission from clusters of galaxies is still an enigma, whose nature is debated. One of the possible
  mechanism to produce this emission  is the bremsstrahlung model.
  However, previous analytical and numerical calculations showed that in this
  case the intracluster plasma had to be overheated very fast because
  suprathermal electrons emitting the HXR excess lose their energy mainly by
  Coulomb losses, i.e. they heat the background plasma. It was concluded also
  from these investigations that it is problematic to produce emitting
  electrons from a background plasma by stochastic (Fermi) acceleration because
  the energy supplied by external sources in the form of Fermi acceleration is
  quickly absorbed by background plasma. In other words the Fermi acceleration
  is ineffective for particle acceleration. We revisited this problem and found
  that at some parameters of acceleration the rate of plasma heating is rather
  low and the acceleration tails of non-thermal particles are generated and
  exist for a long time while the plasma temperature is almost constant . We
  showed also that for some regimes of acceleration the plasma is cooled down
  instead of to be heated up, though external sources (in the form of external
  acceleration) supply energy to the system. The reason is that in the last
  case the acceleration subtracts effectively high energy particles from the
  thermal pool that is the reason of plasma cooling (analogue of Maxwell's
  demon). |