On the possibility of achieving ignition with ions accelerated via laser-driven electrostatic shocks in the corona of an inertial confinement fusion pellet

Ion-driven fast ignition is a promising approach to inertial confinement fusion. In the traditional scheme, ions are accelerated via Target Normal Sheath Acceleration from a target placed outside the hohlraum [1].

In this work, instead, we investigate the possibility of accelerating protons directly in the corona plasma surrounding the compressed Deuterium-Tritium pellet. By performing two-dimensional Particle-In-Cell simulations with the code OSIRIS [2], we show that an intense laser interacting with the underdense corona plasma drives an electrostatic shock. This nonlinear wave travels through the corona and, acting as a moving wall, reflects the hydrogen ions. As a result, a proton beam with an average energy of 8 MeV and an energy spread of 40% is generated. Ions with such characteristics will be able to penetrate the dense core and deposit their energy there. We estimate that employing more than one laser beam to drive multiple shocks will satisfy the energy requirements to create the ignition spark [3].  

[1] Roth et al., Phys. Rev. Lett. 86, 436 (2001). [2] Fonseca et al., Lect. Notes Comp. Sci. 2331, 342 (2002). [3] Boella et al., Phil. Trans. R. Soc. A. 379, 20200039 (2021).