Relativistic proton emission from ultrahigh-energy-density nanosphere generated by microbubble implosion

Abstract

Laser intensity scalings are investigated for accelerated proton energy and attainable electrostatic field using microbubble implosion (MBI). In MBI, 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. 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.

Sign reversal in magnetic field amplification by relativistic laser-driven microtube implosions

“…1f). This process can generate high plasma density at the target center and produce high ion energy from the explosion 31,32 .…”

“…Lasers irradiating a microtube target consisting of a thin opaque shell surrounding a small cylindrical void are capable of driving strong ion acceleration via a two stage process consisting of an initial ion implosion and later ex-plosion 31,32 . It has recently been demonstrated that this process can also generate strong magnetic fields, which are enhanced by the application of a kilotesla-level seed magneic field 30 .…”

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.…”

100-kT Magnetic field generation using paisley targets by femtosecond laser-plasma interactions

“…Modern developments in relativistic femtosecond lasers 1,2 and microstructure fabrication 3,4 have expanded the scope of high energy density physics [5][6][7] . Recently, studies have utilized these developments to investigate ion acceleration 8 , magnetic field generation 9 , ultra-high density compression 10,11 , and pair-creation 12 . Generating magnetic fields on the 100-kT scale is exciting because it enables the study of fundamental phenomena such as magnetic reconnection [13][14][15] .…”