Ignition and high gain with ultrapowerful lasers*

Abstract

Ultrahigh intensity lasers can potentially be used in conjunction with conventional fusion lasers to ignite inertial confinement fusion (ICF) capsules with a total energy of a few tens of kilojoules of laser light, and can possibly lead to high gain with as little as 100 kJ. A scheme is proposed with three phases. First, a capsule is imploded as in the conventional approach to inertial fusion to assemble a high-density fuel configuration. Second, a hole is bored through the capsule corona composed of ablated material, as the critical density is pushed close to the high-density core of the capsule by the ponderomotive force associated with high-intensity laser light. Finally, the fuel is ignited by suprathermal electrons, produced in the high-intensity laser-plasma interactions, which then propagate from critical density to this high-density core. This new scheme also drastically reduces the difficulty of the implosion, and thereby allows lower quality fabrication and less stringent beam quality and symmetry requirements from the implosion driver. The difficulty of the fusion scheme is transferred to the technological difficulty of producing the ultrahigh-intensity laser and of transporting this energy to the fuel.

Evidence of anomalous resistivity for hot electron propagation through a dense fusion core in fast ignition experiments

“…However, in the presence of an inhomogeneity an additional drift velocity V n = B × ∇n/n 2 for the structure exists. This can be observed by substituting for g from equation (2) to equation (1). Here B is the magnetic field associated with the structure.…”

“…Efforts to realize laser fusion received a major boost with the fast ignition proposal in 1994 [1]. This proposal seeks to implode/compress a fusion pellet by multiple, high-energy, nanosecond laser pulses and then strike a spark in the compressed core at the time of maximum compression.…”

Self-focusing of a high-intensity laser pulse by a magnetized plasma lens in sub-relativistic regime

“…These self-generated (or externally applied) transverse and axial magnetic fields affect the propagation of laser pulses in plasmas since the canonical momentum in a magnetized plasma is not conserved [6,7]. Furthermore, laser pulse interaction with magnetized plasmas finds various applications for different branches such as: nonlinear interaction [8], wakefield excitation [9], modulation instability [10,11], laser fusion schemas [12,13], and fast ignition schemes in inertial confinement fusion (ICF) [14]. Moreover, self-generated magnetic fields in the corona region have been studied for intense laser pulse interaction with magnetized plasmas.…”

The effect of grading the atomic number at resistive guide element interface on magnetic collimation

“…This implies that the product of B / L / needs to be larger than the fast electron momentum to reflect the fast electrons back towards the guide axis. The resistive guide has been suggested for applications such as the Fast Ignition approach to the inertial confinement fusion scheme 6,7 where the energetic fast electrons need to be guided through an overdense stand-off distance of 100 lm or more 8 and deposited into the compressed core of deuterium-tritium (DT) plasma. It has been suggested that a resistive guide element can also be used as a driver in hydrodynamic experiments 4,9 since strong heating occurs where the fast electron beam is collimated.…”