The US Naval Research Laboratory (AFL) is developing an argon fluoride (ArF) laser that could one day make fusion energy a practical commercial technology. The wide bandwidth ultraviolet laser is designed to have the shortest laser wavelength that can scale to power a self-sustaining fusion reaction.
Calling fusion energy a game-changing technology is like saying that fire may one day find a practical application. In fact, the ability to generate clean energy from hydrogen in any desired amount over a predictable time scale would fundamentally change civilization in ways we cannot imagine.
Problem is, the melting power sounds like the proverbial rabbit pie recipe that begins with “First, catch your bunny.” While we can recreate the conditions found inside the Sun to produce fusion reactions on Earth, these are relegated to hydrogen bombs and lab experiments where it takes more energy to create the fusion reaction. that we can’t get out of it – although recent experiences are getting much closer to turning the tide.
The goal for the past 75 years has been to produce temperatures above 100 million degrees C (180 million degrees F) and the pressure necessary to trigger the fusion reaction and generate enough excess energy to keep it going. This in itself would be a major achievement, but the technology must also be able to sustain the reaction indefinitely, while being cheap enough and the reactor small enough to be practical.
The LNR ArF laser is intended for a test bench based on the principle of inertial confinement fusion (ICF). In this case, a bead of deuterium or tritium, which are heavy isotopes of hydrogen, is shot by several lasers, heating and compressing it in a fraction of a second to such an extent that the hydrogen atoms implode, merge and release huge amounts of energy.
The new deep ultraviolet laser, also known as the laser pilot, is believed to transfer energy to the fuel bead with greater efficiency and produces much higher temperatures to generate the implosion. Using radiation hydrodynamics simulations, scientists at NRL say performance could be increased a hundredfold with an efficiency of 16%, compared to just 12% of the next most efficient krypton fluoride laser.
Due to these improvements, the ArF laser could lead to smaller and cheaper fusion power plants. However, the team points out that there is still a long way to go before the merger is hooked up to the national grid. The laser will need to deliver the energy, repetition rate, precision and reliability of the billion-shot class required for a convenient installation.
To move in this direction, the laboratory is carrying out a three-phase program, the first of which is dedicated to fundamental science and ArF laser technology. This will be followed by phase two, which will focus on building and testing a large-scale high-energy ArF laser, and then phase three where an implosion facility consisting of 20-30 lasers will be built.
âThe benefits could facilitate the development of smaller, less expensive fusion power plant modules that operate at laser energies of less than one megajoule,â says Steve Obenschain, Ph.D., physics researcher at NRL. “It would radically change the current view that laser fusion energy is too expensive and power plants too big.”
The research was published in the Philosophical Transactions of the Royal Society.