The above image depicts the old-fashioned approach to laser-triggered fusion as practised by the National Ignition Facility.
The newer, cleaner, more scalable and more practical approach discussed below, is apt to beat the older and more expensive approaches to real world applications.
The laser-induced nuclear fusion process in ultra-dense deuterium D(0) gives a heating power at least a factor of 2 larger than the laser power into the apparatus, thus clearly above break-even. This is found with 100-200 mJ laser pulse-energy into the apparatus. No heating is used in the system, to minimize problems with heat transfer and gas transport. This gives sub-optimal conditions, and the number of MeV particles (and thus their energy) created in the fusion process is a factor of 10 below previous more optimized conditions. Several factors lead to lower measured heat than the true value, and the results found are thus lower limits to the real performance. With the optimum source conditions used previously, a gain of 20 is likely also for longer periods. __ Novel Fusion Approach for Heat Generation
Scientists from the University of Gothenberg and the University of Iceland have developed a novel approach to clean, small nuclear fusion. It promises to be equally suitable for either heat or electricity generation, and practical heat and/or electricity generators with 20X energy gain, may be developed within a handful of years.
Fusion energy may soon be used in small-scale power stations. This means producing environmentally friendly heating and electricity at a low cost from fuel found in water. Both heating generators and generators for electricity could be developed within a few years, according to research that has primarily been conducted at the University of Gothenburg.
… The new fusion process can take place in relatively small laser-fired fusion reactors fuelled by heavy hydrogen (deuterium). It has already been shown to produce more energy than that needed to start it. Heavy hydrogen is found in large quantities in ordinary water and is easy to extract. The dangerous handling of radioactive heavy hydrogen (tritium) which would most likely be needed for operating large-scale fusion reactors with a magnetic enclosure in the future is therefore unnecessary…. A considerable advantage of the fast heavy electrons produced by the new process is that these are charged and can therefore produce electrical energy instantly.
No neutrons are produced, which should simplify reactor design and operation immensely — not to mention making the entire approach safer than many other approaches to fusion.
More from published AIP research paper:
Laser-induced nuclear fusion processes1,2 are expected to occur quite easily in ultra-dense deuterium D(0). The theoretical understanding of this material has recently been improved.3 Laser-induced fusion in D(0) using nanosecond and picosecond pulsed lasers has been reported.4–10 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. This means an energy density of 1019 J m−3 only from the bonding energy, and an energy density at least 103 higher from nuclear fusion. Lipson et al.11 have reported experimental results on very high density hydrogen clusters in voids (Schottky defects) measured by SQUIDS in palladium crystals. The close relation between these hydrogen clusters and D(0) has been pointed out.12 Theoretical results for the laser intensity needed for break-even13 and extrapolations from experimental results on D(0)5 indicate that approximately 1 J laser pulses are required for break-even. It was recently reported8,9 that break-even has been reached in fusion in D(0) even with 0.2 J laser pulses. The proof of nuclear fusion in the processes published so far lies mainly in the generation of massive particles with energy >10 MeV u−16,8–10 at the low laser intensity of ❤ × 1013 W cm−2. Recently, also laser-generated penetrating particle emission has been observed by pulse height analysis.14 These results give definitive proof of nuclear processes. Here, the goal is extended to give proof also for heat generation around break-even, of direct interest for the application of nuclear fusion for power generation. The results also 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 Note that in the following H means all isotopes of hydrogen, with p, D and T used explicitly only when needed.
The nuclear processes taking place in the D(0) material are probably not only ordinary D+D fusion. However, the typical 4He and 3He particle emissions from the processes have been reported17 together with a neutron signal with a temperature of 80-600 MK (7-60 keV). Thus, this point will not be discussed further here. The initiation of the fusion processes in D(0) is not due to laser heating to high temperature which has been shown to be inconvenient.16,18 Instead, the process is a laser-induced transfer to the spin state s = 1 which has a d-d distance of only 0.56 pm.3 From this distance, fusion is spontaneous. This type of process is described more in detail in Ref. 19.
One hoped-for advantage of laser-induced fusion is that the reactor may be relatively small with little influence on the environment. In the most often considered form of nuclear fusion D+T, the neutronicity thus the energy fraction carried away by the neutrons is 0.80.20 This means that 80% of the energy released is difficult to contain and use since it leaves the reactor with the neutrons, if the reactor is not large enough (several m) to retain the neutron energy. This means that small reactors are not possible, also from a radiation protection point of view. For this reason, aneutronic fusion reactions like D + 3He are preferable, since only charged particles p + 4He are produced. The high neutronicity of D+T means that only a small fraction of the energy generated can be used for electric power generation in a small fusion reactor, maybe only 0.3 × 0.2 = 6%, assuming a thermal efficiency of 0.3 for converting heat to electricity which is normal for nuclear power plants. The fusion process D+D used here is better in principle, easily shown to have a neutronicity of 0.66 (values from Ref. 20) since 3He is assumed not to react efficiently at the low reactor plasma temperature while T reacts on rapidly with D to form n + 4He. This is supported by TOF-MS laser-driven fusion experiments in the same system, where 3He is observed but not T.17 This means that a maximum of 34% of the energy released may be retained in the apparatus in the present experiments. If also 3He reacts with D at high enough temperature, the neutronicity of D+D is only 0.34, leaving 66% of the energy in charged particles.20 Of course, some radiation losses (for example bremsstrahlung in the reactor walls) may occur from the charged products, making it difficult to use (or even measure) all the energy in the charged fusion products.
The research article above discusses heat generation primarily, but as mentioned earlier in this posting, this novel approach to fusion should be equally capable of producing electricity directly from the fusion products — without the nuisance and hazard of nasty neutron production.
Other approaches to laser-triggered fusion:
The laser-triggered fusion processes shown above could utilise discrete deuterium packets. 600 mg of deuterium could yield as much energy as 5,000 litres of petrol.
But such discrete fusion processes may be forced to make way for the novel, more continuous process developed by the University of Gothenberg and U. of Iceland, utilising very high density deuterium D(0), which lends itself naturally to the scalable production of either heat or electricity.
If this approach proves practical, it may also reach scalable commercial application before other novel forms of unconventional nuclear energy, such as lattice assisted or low energy nuclear reactors (LENRs).
If you take just a few minutes to browse the offerings of the above few LENR sites, you will notice an incredible range of approaches to obtain above-chemical-breakeven low energy reactions. The evidence to support a nuclear origin of the observed excess energy may vary in quality from paper to paper, or from author to author.
Although the main focus of this posting is the groundbreaking research on ultra-dense hydrogen H(0) and ultra-dense Deuterium D(0) from U. Gothenberg and U. Iceland, it would be unwise to dismiss the ongoing parallel research in LENR or LANR phenomenon by a multitude of scientists out of hand, without a close look.