A Review of Nuclear Pumped Lasers and Applications (Asteroid Deflection)

Abstract

A graduate course focused on bringing cutting edge research into the classroom, titled Nuclear Pumped Lasers and applications, was taught at the University of Missouri in 1991 as a topics course; due to renewed interests in high power/high energy lasers for civilian applications, the course has been updated with new research and is being offered in the spring of 2014. Nuclear-Pumped Laser (NPL) technology was a part of the strategic defense initiative (SDI) program in the 1980’s. NPLs have since faded from the United States research agenda but they remain an active part of the research agenda in other countries, notably in Russia and other nations in the former Soviet Union as well as China [1] which has a cooperative agreement with Russia [2]. The reason for this broad interest in the technology is that a NPL can scale to high power/energy levels (potentially up to 100 MW Continuous Wave (CW) beam power). Military applications have historically dominated the NPL research agenda. However, there are significant humanitarian applications for high power/energy lasers. For example a high power CW NPL would have the capability to deflect asteroids or comets. Other important applications are in space propulsion, power transmission, and asteroid mining. Despite the promise, there are significant problems in NPL development [3, 4]. High power/high energy gas lasers by their nature require high pumping power densities (defined as the Watts/cm 3 deposited in the laser medium). That is why many of the most powerful gas lasers are pulsed. Nuclear-pumping does not generate high power densities as compared to electrical pumping, but it does generate high energy densities. This limits the type of high power/high energy gas laser systems that can be driven by NPL technologies. Other issues involve the size and scale of NPLs using gas laser technology as well as the design of reactor cores dedicated to the production of laser beams. Several promising approaches were developed including the development of nuclear-driven flashlamps [5] which can increase the effective pumping power density through photon focusing and thus open up new possibilities for both gaseous and solid-state high power/high energy laser systems.