Prototype for two beam laser fusion system within a decade if no major hurdles arise

Dramatic advances in laser technology are close to making the two-laser approach feasible, and a spate of recent experiments around the world indicate that an ‘avalanche’ fusion reaction could be triggered in the trillionth-of-a-second blast from a petawatt-scale laser pulse, whose fleeting bursts pack a quadrillion watts of power. If scientists could exploit this avalanche, Hora said, a breakthrough in proton-boron fusion was imminent.

“It is a most exciting thing to see these reactions confirmed in recent experiments and simulations,” said Hora, an Emeritus Professor of Theoretical Physics at UNSW. “Not just because it proves some of my earlier theoretical work, but they have also measured the laser-initiated chain reaction to create one billion-fold higher energy output than predicted under thermal equilibrium conditions.”

An Australian spin-off company, HB11 Energy, holds the patents for Hora’s process. “If the next few years of research don’t uncover any major engineering hurdles, we could have a prototype reactor within a decade,” said Warren McKenzie, managing director of HB11.

“From an engineering perspective, our approach will be a much simpler project because the fuels and waste are safe, the reactor won’t need a heat exchanger and steam turbine generator, and the lasers we need can be bought off the shelf,” he added.

Hora, H., Eliezer, S., Kirchhoff, G., Nissim, N., Wang, J., Lalousis, P., . . . Kirchhoff, J. (2017). Road map to clean energy using laser beam ignition of boron-hydrogen fusion. Laser and Particle Beams, 35(4), 730-740. doi:10.1017/S0263034617000799

With the aim to overcome the problems of climatic changes and rising ocean levels, one option is to produce large-scale sustainable energy by nuclear fusion of hydrogen and other very light nuclei similar to the energy source of the sun. Sixty years of worldwide research for the ignition of the heavy hydrogen isotopes deuterium (D) and tritium (T) have come close to a breakthrough for ignition. The problem with the DT fusion is that generated neutrons are producing radioactive waste. One exception as the ideal clean fusion process – without neutron production – is the fusion of hydrogen (H) with the boron isotope 11B11 (B11). In this paper, we have mapped out our research based on recent experiments and simulations for a new energy source. We suggest how HB11 fusion for a reactor can be used instead of the DT option. We have mapped out our HB11 fusion in the following way:
(i) The acceleration of a plasma block with a laser beam with the power and time duration of the order of 10 petawatts and one picosecond accordingly.
(ii) A plasma confinement by a magnetic field of the order of a few kiloteslas created by a second laser beam with a pulse duration of a few nanoseconds (ns).
(iii) The highly increased fusion of HB11 relative to present DT fusion is possible due to the alphas avalanche created in this process. (iv) The conversion of the output charged alpha particles directly to electricity.
(v) To prove the above ideas, our simulations show for example that 14 milligram HB11 can produce 300 kWh energy if all achieved results are combined for the design of an absolutely clean power reactor producing low-cost energy.

Summary of the two beam laser fusion method from the patent

These objects are achieved by a method for generating electrical energy and a nuclear fusion reactor having the features of the independent claims. Advantageous embodiments and uses of the invention result from the dependent claims.

According to a first broad aspect of the invention, the above object is achieved by a method for generating electrical energy by means of inertial nuclear fusion (inertial confinement fusion) in which a fusion fuel, preferably comprising hydrogen and boron 11, is held within a magnetic field in a cylindrical reaction chamber, and a nuclear fusion reaction is initiated in the fusion fuel by using fusion laser pulses (also referred to as block fusion laser pulses), the pulse duration of which is less than 10 ps and the power of which is more than 1 petawatt. The energy released during nuclear fusion from the nuclei that are produced is converted into electrical energy. According to the invention, the magnetic field has a field strength which is greater than or equal to 1 kilotesla. The nuclear fusion preferably produces an energy yield of more than 500, in particular tore than 1000 per laser energy of the fusion laser pulses used to initiate the fusion flame. The tern fusion flame refers to the fusion reaction by picosecond initiation with block ignition (as distinguished from thermal fusion detonation).

According to a second general aspect of the invention, the above object is achieved by a nuclear fusion reactor, which is configured for generating electrical energy, and a magnetic field device which is configured for holding fusion fuel and for generating a magnetic field in a cylindrical reaction chamber, a fusion laser pulse source, configured for emitting fusion laser pulses having a pulse duration of less than 10 ps and a power of more than 1 petawatt and for initiating nuclear fusion in the fusion fuel, and an energy conversion device, which is provided for converting the energy released in the nuclear fusion reaction from the nuclei that are produced into power plant power. The magnetic field device is preferably configured to hold the fusion fuel by means of electrically insulating fibers, e.g. made of quartz. According to the invention, the magnetic field device is configured for generating the magnetic field with a field strength that is greater than or equal to 1 kT.

According to the invention, magnetic fields having a field strength of equal to or greater than kilotesia are preferably used, with the fields more preferably being controlled by a laser-controlled discharge. Advantageously, with the magnetic fields used according to the invention, for the first time he radial losses from a magnetic cylindrical reaction chamber of HB11 with consecutive reactions are prevented such that high yields particularly of greater than 1000 and much more are achieved, with the ps laser pulses having a particularly preferred power of a least 10 PW. The inventors have found tha the magnetic fields are suitable for reliably containing the expansion of the reaction volume during ignition of the nuclear fusion.

The invention offers the advantage of providing, for the first time, a realistic and economically feasible realization of a fusion-based, practically inexhaustible and inexpensive energy source. The nuclear fusion reactor according to the invention is a fusion power plant for practical use. The invention provides highly efficient laser nuclear fusion with magnetic channeling, in which laser-powered nuclear fusion is achieved with yields greater than 500 by applying extremely high magnetic fields.

Advantageously, the ultrahigh magnetic fields [8] of greater than one kilotesla, previously known in only one case, are used, as compared with conventional methods for generating a more than thirty times higher magnetic field, however instead of fusion which is thermally driven in nanoseconds, a non-thermal block ignition achieved with picosecond pulses is used. In dramatic contrast to all previous methods and configurations, this method enables energy yields to be achieved which lead to the realization of economically operated power plants with overall negligible nuclear radiation.

According to preferred embodiments of the invention, the fusion fuel has at least one of the following features. According to a first variant, the fusion fuel preferably has a solid state density of up to 20 times the compression as compared with uncompressed fuel, similar to the case of “fast ignition” according to Nuckolls et al. [1]. According to a further variant, the fusion fuel preferably consists of 11B isotopes with up to a 15% deviation of light hydrogen in terms of stoichiometry. According to a further variant, the fusion fuel preferably consists of a mixture of light hydrogen and boron, each in at least a 20% atomic concentration.

If, accord g to a further advantageous embodiment of the invention, the energy of the nuclei generated is captured by electrostatic fields, further advantages in terms of energy yield are achieved. The fusion energy can be converted directly into electrical energy. Preferably, the kinetic energy of the alpha particles produced is converted directly into electrical energy.

To generate the electrostatic fields, the reaction chamber, more particularly the magnetic field device for forming the reaction chamber, is preferably surrounded by the energy conversion device, the reaction chamber having a negative high voltage relative to the energy conversion device. For this purpose, the reaction chamber, in particular the magnetic field device, is preferably connected to a high voltage source for generating a negative high voltage relative to the energy conversion device. Particularly preferably, the negative high voltage is at least 1 MV.

If, according to a further variant of the invention, the energy conversion device is at ground potential, advantages with respect to the configuration of the nuclear fusion reactor and the feeding thereof with fusion fuel are achieved. The energy conversion device is preferably in the form of a spherical, electrically conductive enclosure (housing) around the reaction chamber, in particular the magnetic field. Advantageously, the energy conversion device is thereby optimally adapted to the fusion geometry.

Particularly preferably, between the energy conversion device and the reaction chamber a Faraday cage is provided for shielding the static high voltage field from the reaction processes, preventing any penetration of the high-voltage field into the fusion reaction volume.

The magnetic field having a field strength of greater than or equal to 1 kilotesla can be realized by any available method for generating strong magnetic fields. According to a particularly preferred embodiment of the invention, the magnetic field is generated by means of an interaction with discharge laser radiation by a discharge current in electrodes which are coupled via at least one coil, in particular a single coil winding. The magnetic field device of the nuclear fusion reactor preferably has a pair of electrodes, two coils and a magnetic field pulsed laser source, which is provided for irradiating the electrodes with discharge laser radiation. Preferably, the magnetic field device is configured to hold the fusion fuel by means of electrically insulating fibers, z. B. made of quartz, on the coils or other support elements of the magnetic field device. Particularly preferably, the magnetic field device is implemented with the configuration described in [8] by S. Fujioka, et al. The discharge laser radiation preferably comprises laser pulses (hereinafter: magnetic field generating laser pulses or magnetic field laser pulses) having a pulse duration of less than 20 ns and energy of more than 100 J.

Advantageously, according to a further embodiment of the invention, the magnetic field can be intensified by designing the electrodes for generating the magnetic field to comprise two plates spaced from one another, between which a magnetic field laser pulse absorbing material is arranged, the form of which is adapted to a Rayleigh profile of generated plasma. The material particularly preferably comprises a foam material, such as polyethylene, and the bi-Rayleigh profile of electron density according to FIG. 10.17 of [2] (see FIG. 1 of [4]) is selected.

According to a further, particularly advantageous embodiment of the invention, block ignition is initiated by the fusion laser pulses. For this purpose, the fusion laser pulses preferably have a duration of less than 5 ps and/or a power of at least 1 petawatt. The fusion pulsed laser source for generating the fusion laser pulses having a duration of less than 5 ps preferably comprises the same type of source as the 10 PW-ps laser assembly known from the Institute of Laser Engineering at Osaka University.

The fusion laser pulses preferably have a contrast ratio of at least 106. To achieve this, advance pulses are particularly preferably suppressed up to a time of less than 5 picoseconds before the arrival of a (main) fusion laser pulse at the fusion fuel. Furthermore, benefits in terms of triggering the fusion reaction result when the fusion laser pulses have an intensity of at least 1017 watts per square centimeter upon arrival at the fusion fuel.

According to a further advantageous embodiment of the invention, the fusion fuel is partially or fully encapsulated by a cover layer, particularly on the side of laser-plasma interaction, the cover layer being made of a material which has an atomic weight of greater than 100. The pulse transmission for generating the fusion flame in the reaction fuel is advantageously increased as a result. The cover layer preferably has a thickness equal to or less than 5 microns, and/or it may be formed by vapor deposition.

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