Generation of ultrahigh fields by microbubble implosion

Abstract

Breaking the 100-MeV barrier for proton acceleration will help elucidate fundamental physics and advance practical applications from inertial confinement fusion to tumor therapy. A novel concept of "microbubble implosion (MBI)" is proposed. In the MBI concept, bubble implosion combines micro-bubbles and ultraintense laser pulses of 10 20-10 22 Wcm-2 to generate ultrahigh fields and relativistic protons. The bubble wall protons are subject to volumetric acceleration toward the center due to the spherically symmetric electrostatic force generated by hot electrons filling the bubble. Such an implosion can generate an ultrahigh density proton core of nanometer size on the collapse, which results in an ultrahigh electrostatic field to emit energetic protons in the relativistic regime. Laser intensity scaling is investigated for accelerated proton energy and attainable electrostatic field using MBI. Three-dimensional particle-in-cell and molecular dynamics simulations are conducted in a complementary manner. As a result, underlying physics of MBI are revealed such as bubble-pulsation and ultrahigh energy densities, which are higher by orders of magnitude than, for example, those expected in a fusion-igniting core of inertially confined plasma. MBI has potential as a plasma-optical device, which optimally amplifies an applied laser intensity by a factor of two orders of magnitude; thus, MBI is proposed to be a novel approach to the Schwinger limit.

Laser scaling for generation of megatesla magnetic fields by microtube implosions

“…Consequently, ultrahigh magnetic fields are generated in a collective manner, amplifying the original seed magnetic field by a factor of two to three orders of magnitude. Note if the cylindrical cavity is replaced by a spherical one, based on another physical concept referred to as microbubble implosion [33][34][35][36], ultrahigh electric fields may be obtained close to the Shwinger limit [32] instead of an ultrahigh magnetic field.…”