Xcimer Energy, in collaboration with researchers from several U.S. institutions, has announced a significant advance in laser driver technology for inertial fusion. According to a company press release, experiments have demonstrated a novel pumping mechanism for krypton fluoride (KrF) excimer lasers that achieves greater than 10% wall-plug efficiency. This result addresses a primary obstacle for commercial laser-driven fusion, where the low efficiency of current solid-state laser systems, such as those at the National Ignition Facility, necessitates extremely high target gains for net energy production. The experiments were conducted at the Naval Research Laboratory's Electra facility. Source: Xcimer Energy
The demonstrated technology circumvents the inefficient frequency conversion process used in neodymium-glass lasers. Systems like NIF generate infrared light (1053 nm) and then use nonlinear crystals to convert it to ultraviolet (351 nm), a process with only 50-60% efficiency that contributes to an overall wall-plug efficiency below 1%. In contrast, KrF lasers naturally emit light in the deep UV at a 248 nm wavelength. Xcimer's reported breakthrough lies in the method of exciting the KrF gas medium, which has historically been a low-efficiency process. Achieving over 10% direct wall-plug efficiency for the laser system dramatically lowers the required plasma gain for a viable power plant. Source: Xcimer Energy
The demonstrated technology circumvents the inefficient frequency conversion process used in neodymium-glass lasers.
The shorter 248 nm wavelength of KrF lasers offers additional physics advantages for inertial confinement fusion. This wavelength couples to the target plasma more efficiently and provides higher ablation pressure, which can suppress hydrodynamic instabilities that inhibit ignition. This improved coupling could lead to higher target gains compared to the 351 nm light used in current mainline ICF experiments. The combination of higher laser efficiency and potentially higher target gain significantly improves the prospects for achieving an engineering gain, or Q_engineering, sufficient for commercial electricity generation. The company states a power plant would require a repetition rate of approximately 10 Hz, a regime made more accessible by this gas-laser architecture. Source: Xcimer Energy
This research, which Xcimer states has been published in a peer-reviewed journal, represents a critical validation of the company's technical roadmap. The private fusion company, part of a growing private sector landscape, is now focused on scaling the technology. The next objective is the development of a prototype laser system designed to produce 10 MJ of light energy per pulse. This facility will serve as the core building block for a future fusion prototype plant. Collaborators in the announced work include the Naval Research Laboratory, the University of California San Diego, and Los Alamos National Laboratory. Source: Xcimer Energy