Nuclear fusion is becoming highly popular recently, after many years of slow development. Most importantly the private funding of this research and development now exceeds public funding significantly.  Recent startups aim for new ways especially in the direction of Inertial Confinement Fusion.  In contrast to International Thermonuclear Experimental Reactor (ITER) and Lawrence Livermore Nat. Lab’s National Ignition Facility (NIF) the new ideas aim for affordable and more energy effective solutions.  NAPLIFE is one of these. Early attempts are thermal approaches suffering from instabilities and partial burning of the target fuel.  Thermalization at each step results in 30-40 % energy loss, both at thermalizing laser irradiation to isotropic keV-energy radiation and generating isotropic thermal energy nuclear reactions to achieve fusion.  Fusion energy burn is propagated then by a so-called alpha heating in random thermal processes.

NAPLIFE aims to avoid these losses in an affordable way by exploring the advantages offered by the combination of the nuclear fusion process with nanotechnology in general and nanoplasmonics in particular. Mono-chromatic laser light of a pulsed Ti:Sa laser  with maximum 25mJ pulse energy and around 40 fs pulse length is shot from one or two sides on  up to 160 micrometer  thick, transparent polymer  targets with or without gold nanorods deludedly dissolved in them. The 800 nm laser light excites resonantly the localized surface plasmons on these nanoparticles.

Figure: Craters in the targets without gold (above) and with gold nanoparticles (below). The laser shots were at 45° and the volume of the right figure is about 3.8 times larger.

Present nanotechnology has made this possible in the last decade.  Furthermore, these gold nanorods regulate the absorption of laser light resonantly, with sufficiently short laser pulses which are available only very recently and generate simultaneous ignition to avoid (the usual mechanical) instabilities.

As a further development of this technique, the plasmonic nanoparticles shall be well directed and arranged in adequate arrays in order to optimize the laser wake field driven (ponderomotive) proton acceleration. With the maximal proton energies exceeding the respective thresholds of nuclear fusion reactions the desired nuclear fusion reactions can be achieved without serious losses.  NAPLIFE has already experimentally proved among others the proton acceleration mechanism, and achieved some nuclear reactions leading to deuterium formation, as well as proton-boron fusion leading to alpha particle production, already with 25 mJ laser pulse energies.

The deuteron formation was first detected experimentally by Raman spectroscopy at the surface of the crater drilled in the polymer target by the laser pulse (https://arxiv.org
/abs/2210.00619) and by LIBS spectroscopy of the backward plume after the laser shot. This latter finding has been published recently in Scientific Reports (doi.org/10.1038/s41598-024-69289-4). The proton to deuteron two-step fusion process (pep process) has been found to be exotherm. Significant excess energy has been found by the large increase of the crater volume when resonant gold nanoparticles were implanted into the target, compared to the same sample without these implanted nanoparticles (https://arxiv.org/abs/2402.18138). The high field around the nanoparticles with its Coulomb-barrier screening and proton accelerating effects causes a significant increase of the fusion yield near the surface of the particles. When the polymer sample has been seeded with boron nitride molecules in addition to the gold nanorods p-11B reactions occur producing alpha particles. Their traces have been detected by CR-39 gel detectors.

The following microscopical mechanisms are involved: 1) the laser pulse energy is collected by the resonant-size nanoparticles by converting it into collective electron motion on their surface (localized surface plasmons); 2) the enhanced electric field due to this collective motion accelerates protons nearby; 3) the energetic protons hit further nuclei in the polymer target. This mechanism requires high electron densities in contrary to Coulomb and fermionic repulsion among protons. This is known at low temperatures due to Cooper pair formation, but at high energy densities this is not yet fully established, although there are theoretical conjectures that such processes may occur.  These may catalyze fusion reactions also. The observed proton acceleration and nuclear reactions may support these ideas.

In the perspective, the NAPLIFE project with its non-thermal processes, well directed laser pulses, sophisticated fuel preparation and directed emission of reaction products enable us a fast repetition of separated fusion reactions, unlike in thermal methods where all these processes are isotropic and cannot be separated easily or without considerable losses.

The final step generating electric energy can on the hand be done in the conventional way by heating water, driving steam turbines and then generators.  Some other startups (like the HELION project) attempt to use other nonthermal ways to achieve electric energy by using the current of the emitted charged particles for inducing o current in coils. The efficiency of this energy conversion method is still unknown, and in the beginning, it probably will not exceed the thermal (Carnot) efficiency.

The NAPLIFE project uniquely exploits the latest developments in nanotechnology and in laser technology, as well as theoretical progress in high energy electron density concentration and simultaneous (time-like) detonations.  These ingredients together enable us to work out an affordable energy production technology from nuclear fusion in the future.