演講資訊

摘要：

Nonthermal energetic particles or cosmic rays are ubiquitous in the universe. The diffusive shock acceleration is considered to be a standard theory for the acceleration of galactic cosmic rays, however, the origins of extragalactic cosmic rays are not well understood. In the presence of a relativistic collisionless shock, wakefield induced by the precursor light waves in the upstream can efficiently accelerate particles. Numerical studies show that the wakefield can nonthermally accelerate particles and the energy distribution functions of the accelerated particles are well represented by power law with an index of -2, independent of the light and plasma conditions. Although it had been difficult to prove such analytic and numerical models with observations, recent laser technologies allow us to access such extreme astrophysical conditions. Here we show the experimental results with the 100 TW laser facility at National Central University. We report for the first time that turbulent wakefield nonthermally accelerates particles and universally generates power spectra with an index of -2 independent of laser and plasma conditions.