Proton Fast Ignition

Fast ignition by a laser-generated, ballistically focused proton plasma jet is a more recently proposed alternative to the original concept of fast ignition by a laser-generated beam of relativistic electrons. It has potential advantages in less-complex energy transport into dense plasma but has been investigated only at a preliminary level. Recent successful target heating experiments motivate further investigation of its feasibility. The concept and requirements, the characteristics of the proton plasma jets, the recent experimental work on focusing the jets and heating solid targets, and the overall physics constraints and unresolved questions are discussed.