Abstract
Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu) cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0) of ultra-dense hydrogen (size of a few pm) escape with a substantial fraction of the energy. Heat loss to the D2 gas (at <1 mbar pressure) is measured and compensated for under various conditions. Heat release of a few W is observed, at up to 50% higher energy than the total laser input thus a gain of 1.5. This is uniquely high for the use of deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.
Highlights
Laser-induced nuclear fusion processes[1,2] are expected to occur quite in ultra-dense deuterium D(0)
Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy > 10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used
The results show that laser-induced fusion is easier to use with other fuels than the normal D-T ice which appears to give compression instabilities even when using MJ laser pulses.[15,16]
Summary
Laser-induced nuclear fusion processes[1,2] are expected to occur quite in ultra-dense deuterium D(0). The theoretical understanding of this material has recently been improved.[3] Laserinduced fusion in D(0) using nanosecond and picosecond pulsed lasers has been reported.[4,5,6,7,8,9,10] The reason for the quite facile fusion processes is the high density of D(0), close to 1029 cm−3 or 140 kg cm−3. The close relation between these hydrogen clusters and D(0) has been pointed out.[12] Theoretical results for the laser intensity needed for break-even[13] and extrapolations from experimental results on D(0)[5] indicate that approximately 1 J laser pulses are required for break-even It was recently reported[8,9] that break-even has been reached in fusion in D(0) even with 0.2 J laser pulses. The goal is extended to give proof for heat generation around break-even, of direct interest for the
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