Laser-induced fusion in ultra-dense deuterium D(-1) is reported in several studies from our group, using ns- and ps-pulsed lasers. The ejection of ultra-dense hydrogen particles with thermal distributions and energy up to 20 MeV u−1 was studied previously by time-of-flight measurements. The investigations of the new processes continue now by studying the interaction of these particles with metal surfaces. In the present experiments, such particles penetrate in two steps through 1 mm of metal and reach three levels of collectors at distances up to 1 m. Only the fastest particles penetrate and move to the next level. The thermal time-of-flight distributions together with tests with strong magnetic fields exclude electrons as the particles observed. The sign of the signals to the metal collectors depends on the bias (negative bias gives positive signal and conversely) while the time variations of the signals for positive and negative bias are similar. The rapid variation of the signals indicates electrons and positrons ejected from the collectors, thus lepton-pair production. An increase in bias up to ± 400 V increases the peak signal up to 1 A with no observed limiting. A thick metal plate removes slow particles and most gamma photons. The number of lepton-pairs produced is > 4 × 1012 sr−1 in the forward direction per laser shot.

Nuclear fusion in ultra-dense deuterium D(-1) was reported previously to be induced by 0.2 J pulses with 5 ns pulse length, ejecting particles with energies in the MeV range. The ns-resolved signal from D(-1) to two in-line collectors at up to 1 m distance can be observed directly on an oscilloscope, showing particles with energies in the range 1–20 MeV u−1. They are probably mainly protons and deuterons in the form of neutral ultra-dense hydrogen H(-1) fragments. Electrons and photons give only small contributions to the fast signal. The observed signal at several mA peak current corresponds to 1 × 1013 particles released per laser shot and to an energy release >4 J assuming isotropic formation and average particle energy of 3 MeV. This corresponds to an energy gain of 30 in the process. A movable slit close to the laser target gives lateral resolution of the signal generation, showing almost only fast particles from the point of laser impact and penetrating photons from the plasma outside the laser impact point. The observation of multi-MeV particles indicates nuclear fusion, either as a source or as a result.

The short D-D distance of 2.3 pm in the condensed material ultra-dense deuterium means that it is possible that only a small disturbance is required to give D+D fusion. This disturbance could be an intense laser pulse. The high excess kinetic energy of several hundred eV given to the deuterons by laser induced Coulomb explosions in the material increases the probability of spontaneous fusion without the need for a high plasma temperature. The temperature calculated from the normal kinetic energy of the deuterons of 630 eV from the Coulomb explosions is 7 MK, maybe a factor of 10 lower than required for ignition. We now report on experiments where several types of high-energy particles from laser impact on ultra-dense deuterium are detected by plastic scintillators. Fast particles with energy up to 2 MeV are detected at a time-of-flight as short as 60 ns, while neutrons are detected at 50 ns time-of-flight after passage through a steel plate. A strong signal peaking at 22.6 keV u−1 is interpreted as due to mainly T retarded by collisions with H atoms in the surrounding cloud of dense atomic hydrogen.