Suprathermal Grains: Origin of primary cosmic rays

Abstract

Charged dust grains of radiia≃3×10−6 cm could be a help in understanding the production of primary cosmic ray particles in extensive air showers (EAS). A two-stage acceleration mechanism is proposed in order to accelerate dust grains up to relativistic energy. In the first stage, dust grains acquire suprathermal energy (‘Suprathermal Grains’) by the Fermi mechanism. In the second stage, suprathermal grains attain relativistic energy by the Alfven magnetic pumping mechanism yielding the primary cosmic ray particles. Ionization loss has been considered to be a most important loss mechanism for charged dust grains in a fully ionized medium. It is suggested that graphite dust grains of intergalactic origin may be responsible for high energy (>1020 eV) cosmic rays.