Fusion reactor using optical control of quantum tunneling

Abstract

A fusion system uses optical pulse shaping to control a fusion reaction by manipulating the quantum state of fluid fuel. The fusion system includes a reactor assembly that accepts fusion reaction fuel (e.g., hydrogen, hydrogen deuteride, deuterium, or deuterium-tritium, liquid water, liquid 17O-heavy water, etc?), and provides for conversion of high-energy fusion products to current. The fusion system may operate at ambient or low temperature (relative to ambient conditions), in the infrared band of the electromagnetic spectrum (e.g., between 700nm and 16000nm), and at moderate field intensities (e.g., between 109W / cm2 and 1017W / cm2), enabling efficient use of compact femtosecond laser sources and in-line, passive, or active optical elements for ultrafast pulse shaping. The net result is a field-robust electrical generator assembly that may be seamlessly integrated into existing electrical infrastructures.

Description

FUSION REACTOR USING OPTICAL CONTROL OF QUANTUM TUNNELINGInventors:Jacob Levitt Dmitri KharzeevArtur IzmaylovCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Nos. 63 / 596,122, filed November 3, 2023, 63 / 653,161, filed May 29, 2024, 63 / 668,615, filed July 8, 2024, and 63 / 682,691, filed August 13, 2024, all of which are incorporated by reference.BACKGROUND1. TECHNICAL FIELD

[0002] The subject matter described generally relates to fusion power, and, in particular, to a system that uses optical pulses to control a fusion reaction.BACKGROUND INFORMATION

[0003] Nuclear fusion reactors have been pursued for a long time with tantalizing prospects of a future energy source. In general, conventional approaches to fusion require confining a plasma of carefully chosen nuclear isotopes (e.g., hydrogen isotopes), and the major challenge in modem reactor development is to create and maintain plasma of several 108K. In one class of reactors, magnetic or inertial confinement is used. Another approach that has been considered is a confinement mechanism known as “chemical confinement” in which an elementary particle, the muon (μ), is used to achieve nuclear fusion at room temperature and below. Because the μ mass is 207 times larger than the mass of an electron, the μ orbits much closer to the nucleus in muonic atoms, and in muonic molecules can strongly squeeze two nuclei such that nuclear fusion reactions occur by the overlap of nuclear wavefunctions as opposed to by stochastic high-energy collisions. The idea of μ-catalyzed fusion was proposed by Frank (1947) and Sakharov (1948) independently, followed by more detailed theoretical considerations by Zeldovich (1954). Experimental observation of μ-c atalyzed fusion was first reported in 1956, where a muonic molecule pdμ (in which μ binds a proton p and a deuteron d with chemical binding energy 220eV) induced the fusion reactiond(p,y)3He at ambient temperatures, at a rate accelerated by nearly 100 orders of magnitude relative to the spontaneous rate of fusion in electronic molecules.

[0004] Muonic molecules exhibit two chemical properties that allow them to accelerate the intramolecular fusion rate at ambient temperatures. The first is a drastic increase in chemical binding energy (from 2.8eV in electronic hydrogen molecular ion H2+to ~220eV in muonic hydrogen) and the second is a drastic reduction in chemical bond length (from 105.84pm in electronic hydrogen molecular ion H2+to less than 1pm in muonic hydrogen). In the Wentzel-Kramers-Brillouin (WKB) calculation of intramolecular fusion rates, the binding energy of muonic molecules contributes linearly as a pre-factor, via the higher frequency of nuclear vibrations, in accordance with the Virial theorem, and the chemical bond length determines fusion rates by the exponential of the action along a path connecting the two nuclei. Consequently, fusion rates in muonic molecules can be enriched exponentially by improved Coulomb screening conferred by the contracted orbits of muons bound into atoms comprising the muonic molecule.

[0005] -catalyzed fusion is so far not commercially viable because muons are unstable (decay lifetime 2.2 microseconds), and as such, would need to be consistently produced by secondary events at high-energy particle accelerators. The energy required to produce a relevant flux of muons is much larger than the energy generated from μ-catalyzed fusion. Furthermore, there is a trend in energy sectors towards decentralized, unsupervised, field-stable, and inexpensive power generation, such as solar energy.

[0006] There exists a need to replicate in normal electronic molecules (which have essentially infinite lifetime) the behaviors leading to an accelerated fusion rate in muonic molecules, using instruments which are furthermore commercially mature, inexpensive, field-stable, and energyefficient, such that the energy produced from fusion is greater than the energy used to induce fusion and such that the electricity produced is competitive on energy markets.SUMMARY

[0007] The above and other problems may be addressed by a fusion system that uses optical pulse shaping (e.g., infrared optical pulse shaping) to control a fusion reaction. The fusion system may use modular components that scale well towards commercialization. The system includes a reactor assembly that accepts fusion reaction fuel (e.g., hydrogen, hydrogen deuteride, deuterium, or deuterium-tritium, liquid water, liquid17O-heavy water, etc?), and provides for conversion of high-energy fusion products to current. The fusion system may operate at ambient or low temperature (relative to ambient conditions), in the infrared band of the electromagnetic spectrum (e.g., between 700nm and 16000nm), and at moderate field intensities (e.g., between 109W / cm2and 1017W / cm2), enabling efficient use of compact femtosecond laser sources and in-line, passive or active optical elements for ultrafast pul se shaping. The net result is a field-robust electrical generator assembly that may be seamlessly integrated into existing electrical infrastructures.

[0008] In some embodiments, a fusion reactor system includes a laser source that generates a pulsed input beam. The fusion reaction system also includes an optical assembly that generates an azimuthally polarized vector Laguerre-Gauss or Bessel-Gauss pulsed beam, a circularly polarized scalar pulsed beam, or a bicircular beam, using the pulsed input beam. The beam generated by the optical assembly may be referred to as the “control beam” for convenience. A reaction chamber is configured to contain a fuel (e.g., a fluid fuel, such as hydrogen, hydrogen deuteride, deuterium, deuterium-tritium, liquid water, or liquid17O-heavy water, etc.) and has an optical input. The control beam enters the reaction chamber through the optical input and excites particles of the fluid fuel into an excited state such that a fusion probability exceeds a viability threshold. In some embodiments, the excited state may exhibit an increase to the chemical binding energy of particles of the fluid fuel and a decrease in chemical bond length of particles of the fluid fuel. An energy extractor extracts energy generated by fusion reactions from the reaction chamber.

[0009] In one embodiment, the pulsed input beam has a center wavelength of approximately 1030nm. The pulsed input beam may be made up of femtosecond pulses. The pulsed input beam may be generated using a free-space ytterbium femtosecond laser oscillator. Such an oscillator brings advantages to commercialization of the fusion system in that it can be fabricated as a monolith on a smart-glass substrate, reducing the sensitivity of the laser performance to temperature, humidity, radiation, vibration, and acoustic fluctuations in the reactor environment (e.g., a field- deployed shipping container). The fusion reaction system may also include one or more pulseshaping elements that generate a control beam, from the pulsed input beam. The fusion reaction system may also include one or more beamsplitters and ultrafast mirrors that are used to distribute fractions of the pulsed input beam or control beam to multiple reactor assemblies, or to distribute a shaped beam around a maze-design neutron shield, into the reaction chamber where fusion is actively occurring.

[0010] In other embodiments, the optical beams used for control may be generated using other techniques. For example, a titanium-doped sapphire (Ti:Sapphire) femtosecond laser amplifier maybe used, operating at a center wavelength of 800nm. As another example, a thulium (Tm) femtosecond fiber laser amplifier may be used, operating at a center wavelength of 1950nm. In yet another example, an ytterbium (Yb) femtosecond fiber laser amplifier may be used, operating at a center wavelength of 1030nm. In a further example, an optical parametric amplifier is used, which can emit pulses in the deep ultraviolet from an infrared seed. It should be appreciated that a wide array of femtosecond laser sources generating pulses in the infrared region of the electromagnetic spectrum may be used to produce control pulses with the desired properties.

[0011] In some embodiments, the fluid fuel may be a sample of deuterium gas under pressure (e.g., ~100psi). In other embodiments, a supersonic molecular beam is used to achieve high number density of a fluid fuel. The control beam excites deuterium molecules, increasing the probability of a fusion event occurring due to a particle tunneling through the Coulomb barrier. In one such embodiment, the fusion reactions caused by the control beam are the d(d,n)3He and d(d,p)3H fusion reactions. The resultant fast-spectrum neutron (2.45MeV) is thermalized by a moderator and / or coolant (e.g., a fluoride molten salt) in order to extract energy from the reactor. In other embodiments, the fuel is an isotopologue of water, such as17O-heavy water. In this case, the fusion reaction caused by the control beam is the16O(p,y)17F fusion reaction in liquid water. In another embodiment, the fusion reaction caused by the control beam is the17O(p,y)18F fusion reaction in liquid17O-heavy water.

[0012] In the gas phase, the fluid fuel may be contained in a steel alloy high-pressure gas cell with sapphire, MgFz, or quartz optical ports. In the liquid phase, the fluid fuel may be contained in an optically transparent cuvette, such as a quartz cuvette.

[0013] The fusion may occur while the reaction chamber is at a temperature between approximately zero and approximately one hundred degrees Celsius. The energy extractor may generate heat from fusion products and provide the heat to drive a turbine. In this case, a molten salt loop (e.g., containing a fluoride salt, a chloride salt, LiF / 6LiF / 7LiF, UF4, or TI1F4, with a melting point of around ~500°C, operating at a temperature of around ~600°C to 700°C, with a boiling point of ~1000°C above the melting point) may be used to thermalize neutrons from the reactor. Heat is extracted by pumping the salt in a loop between the reaction chamber and a heat exchanger, with the reactor power being directly proportional to the temperature drop across the heat exchanger and the flow rate. In other embodiments, the reactor coolant and neutron moderator may instead be light or heavy water. In yet other embodiments, the reactor coolant and neutron moderator may be a liquidmetal (e.g., lead-bismuth eutectic moderated with beryllium, sodium, etc.). In still other embodiments, the neutron moderator may be graphite and the reactor coolant helium gas.

[0014] Additionally or alternatively, the energy extractor may include a scintillator (e.g., cerium-doped lutetium iodide, thallium-doped sodium iodide, or cerium / strontium-doped lanthanum bromide) that converts fusion products (e.g., gamma quanta, β+particles) to visible, infrared, or ultraviolet light and a semiconductor (e.g., zinc telluride) that converts visible, infrared, or ultraviolet light into an electrical current. Additionally or alternatively, the energy extractor may comprise an electronic-grade, single-crystal diamond (CVD diamond). Additionally or alternatively, the energy extractor may comprise heavy metal (e.g., lead, nickel) perovskite materials. Additionally or alternatively, the energy extractor may comprise crystalline silicon. The energy extractor may comprise a capacitor assembly for storing current generated by the above energy conversion techniques. It should be noted that the relatively low temperatures at which the reactor may operate facilitate energy harvesting because various energy extractors can (e.g., need only) be adjusted (e.g. , optimized) for radiation hardness as opposed to both radiation and temperature hardness (in the case of an aneutronic reaction; water), and the reaction chamber can (e.g., need only) be adjusted (e.g., optimized) for radiation and pressure hardness as opposed to radiation, pressure, and temperature hardness (in the case of a neutronic reaction; deuterium).

[0015] The concepts described may facilitate commercialization of fusion reactors for use in fusion power plants (e.g., ultra-compact fusion power plants) as well as in (e.g., fundamental) physics applications. However, the disclosed concepts are generally applicable for use in a wide range of other applications (e.g. , a wide range of industrial uses) which may make use of the products of nuclear reactions (e.g., tritium, neutrons, β particles, a particles,3He, high-energy quanta, neutrinos, etc.). Such applications include applications in particle accelerators and detectors (e.g., for use in healthcare applications such as in instruments for radiotherapy), applications in high-energy particle physics, and applications in nuclear counter-proliferation.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a block diagram of an ultrafast laser architecture that can drive a viable fusion reaction with quantum control, according to one embodiment.

[0017] FIG. 2 is a block diagram of a fusion system using optical pulses, according to one embodiment.

[0018] FIG. 3A illustrates optical control of fusion on a first-order Poincare sphere.

[0019] FIG. 3B illustrates optical control of fusion on a higher-order Poincare sphere.

[0020] FIG. 4 illustrates how a circularly polarized laser field with the appropriately chosen characteristics can result in a molecular excitation in which the chemical binding energy is increased and the chemical bond length is decreased, according to one embodiment.

[0021] FIG. 5 is a block diagram of a fusion system using optical pulses, according to one embodiment.

[0022] FIG. 6 is a block diagram of a fusion system using bicircular fields incident on fluid fuel, according to one embodiment.

[0023] FIG. 7 illustrates an example method for inducing fusion in target molecules with a pulsed beam, according to one embodiment.

[0024] FIG. 8 illustrates an example method for inducing fusion in target molecules with a pulsed beam, according to one embodiment.

[0025] FIG. 9 is experimental data using a circularly polarized field and coincident gamma-ray annihilation spectrometry to demonstrate the ability of the present embodiments to accelerate in situ fusion rates, according to one embodiment.

[0026] FIG. 10 shows a spectrum of18F showing a 1" resonance near the breakup threshold into O and p, according to one embodment.DETAILED DESCRIPTION

[0027] The figures and the following description describe certain embodiments by way of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods may be employed without departing from the principles described. Wherever practicable, similar or like reference numbers are used in the figures to indicate similar or like functionality. Where elements share a common numeral followed by a different letter, this indicates the elements are similar or identical. A reference to the numeral alone generally refers to any one of a combination of such elements, unless the context indicates otherwise.OVERVIEW

[0028] There exists a need to replicate in normal electronic molecules (which have essentially infinite lifetime) the behaviors leading to an accelerated fusion rate in muonic molecules, using instruments which are furthermore commercially mature, inexpensive, field-stable, and energyefficient (e.g, sources of coherent light — lasers), such that the energy produced from fusion is greater than the energy used to induce fusion and such that the electricity produced is competitive on energy markets. This may be achieved via Poincare engineering.

[0029] Solutions to the Maxwell equations form a group with SU(2) symmetry, which is parameterized by the Stokes vectors. Poincare engineering involves structuring these light polarization vectors in space and time to alter chiral and topological properties of light (e.g., a laser pulse), such as its helicity, handedness, and scalar phase or vectorial singularities. By combining electromagnetic wave interference with photonic spin-orbit interactions, a textured mapping of photon states onto the surface of a Poincare sphere can be achieved that defines light polarization in terms of its homeomorphic SO(3) representation, the 3D Stokes vector space. Such structured light, which exhibits complex polarization textures, further expands the type of light-matter interaction and therefore the active control over (e.g, fundamental) quantum dynamics of electrons bound into molecules, for example, by establishing a transient and confining effective one-electron potential in field-dressed molecules.

[0030] Field-dressed electronic molecules can exhibit enhanced intramolecular fusion rates relevant for a fusion reactor by utilizing a shaped laser pulse to transiently replicate (e.g., key) properties of muonic molecules such as improved Coulomb screening, via coherent control of quantum mechanical electron motion. This strategy is a priori attractive because modem pulsed laser systems are robust, versatile, energy efficient, and commercially mature instruments. The modern suite of ultrashort pulse laser architectures is amenable to producing the pulse shapes (e.g, frequency, intensity, phase, polarization) used (e.g., required) for controlling electron motion in atoms and molecules effectively to this aim and in a field-stable (industrial) setting. As described in greater detail below, this strategy can be used to design a control protocol that is highly efficient in the near- and mid-infrared bands of the electromagnetic spectrum, which host the center wavelength of a wide array of compact, high-repetition-rate femtosecond laser sources. The optical fusion devices can then take advantage of in-line, passive or active pulse shaping techniques optimized forthese laser sources, which facilitates rapid fabrication of a large number of elegant reactors operating along the concepts, systems, and techniques disclosed herein.

[0031] Furthermore, in the infrared band the disclosed laser control protocol can be realized in condensed phase molecules, such as liquid water, or deuterium gas under high pressure (e.g., ~100psi), both of which are transparent to infrared radiation. As such, a large number of molecules (e.g., on the order of 102°-1021water or deuterium molecules) can be controlled simultaneously to achieve competitive fusion yields. Additionally or alternatively, a supersonic molecular beam is used to achieve high number density of a fluid fuel. Additionally or alternatively, a hollow-core fiber is used to achieve a large interaction volume with molecules of the fluid fuel.QUANTUM CONTROL EXAMPLES

[0032] In various embodiments, a laser is used to manipulate the quantum state of fuel molecules such that spontaneous fusion is likely to occur with sufficient frequency that the system is net energy positive. In particular, the laser may be used to manipulate the magnitude of Coulomb screening of the fuel molecules.The effect of Coulomb screening on nuclear fusion

[0033] Nuclear fusion is governed by the competition between the short-range attractive nuclear force and the long-range Coulomb repulsion among the fusing nuclei. The importance of Coulomb repulsion at a given kinetic center-of-mass energy E is quantified by the Sommerfeld parametereffects are extremely important.

[0034] The fusion cross section can be written asof near-threshold resonances) varies slowly with energy. The exponential accounts for the suppression due to tunneling through the repulsive Coulomb potentialevaluated in semiclassical WKB approximation, as originally derived by Gamow. The WKB Euclidean action is evaluated between the classical turning pointdetermined by the condition E = U (rt) and the nuclear-scale distance rcat which the compound nucleus is formed.

[0035] If the fusing nuclei are part of atoms or molecules, the Coulomb potential is screened by electrons. The appropriate treatment of the screening effects depends on the initial energy E. At low energies, when the relative velocity of the nuclei v(E) is much smaller than the Bohr velocity of bound electronsthe electron cloud can quickly adjust to the motion of the nuclei, and the adiabatic Born-Oppenheimer approximation is appropriate.

[0036] In this adiabatic approximation, the effect of Coulomb screening can be properly accounted for by the screened potential, for which we will assume a simple Debye formwhere rDis the screening radius. The effect of screening on the tunneling probability can be estimated following the approach originally proposed by Salpeter. Namely, the height of the Coulomb barrier near the distance rcwhere the compound nucleus is formed can be estimated fromwhere we have used the Taylor expansion near r = 0, justified by The height of theCoulomb barrier thus gets reduced by the amountand the corresponding increase of the tunneling probability can be estimated by an effective increase of energy, E -» E + Uo. The ratio of penetration probabilities with and without the screening is thus given by

[0037] This quantity can be interpreted as the difference between the energy of the compound atom and the sum of energies of atoms before fusion. In this disclosure we will mostly be interestedin the ultra-low energy limit of E Performing Taylor expansion of the exponent in the aboveequation to leading order in we get

[0038] The fusion cross section at ultra-low energies with the account of Coulomb screening effect is then:

[0039] The Coulomb screening leads to the replacement of the vanishingly small at E — > 0 Gamow factor exp [— const / E] by a small but finite, energy-independent “screened penetration factor”Fusion rates in molecules

[0040] This difference can lead to observable effects in molecules. Consider first the pd fusion in hydrogen deuteride molecule HD. Using the screening radius corresponding to the screened penetration factor

[0041] The stretch vibration frequency of the hydrogen deuteride molecule is about D(HD) = 4,340cm-1= = 11 XX 1 l0O1'^4ss-1. Assuming that the p + d -»3He fusion process occurs every time the Coulomb barrier is penetrated, we estimate the rate of fusion processes in hydrogen deuteride as

[0042] A fusion rate per unit volume per unit time is obtained by multiplying this rate by the density of molecules. Assumingwhich is clearly unobservable. Achieving the fusion rate would requiredecreasing the screening radius by a factor of 18. This estimate is consistent with the results of a more sophisticated analysis based on the R-matrix method.

[0043] The p +16O ->17F fusion reaction in water can be estimated. The symmetric OH stretch frequency in water molecule is £l(OH') = 3,657cm-1= 1 x 1014ss-1The rate of fusion processes in water can thus be estimated ascorresponding to the characteristic lifetime of a gaseous water molecule1042years

[0044] A fusion rate per unit volume per unit time for the density of water n(W20) =3 X 1022cm "3is

[0045] This estimate explains the stability of water with respect to nuclear fusion.Methods to reduce screening radius

[0046] The following description explains the theory on which the fusion system operates. In places, the theory provided may be simplified for illustrative purposes or omit some details for readability. However, one of skill in the art would understand from the following theoretical discussion how the fusion system operates as well as various advantages the system has over conventional approaches to fusion.

[0047] Circularly polarized field: for a circularly polarized (chiral) laser field with frequency co, the classical equation of motion for an electron under the influence of the Lorentz force F(t) = —eE(t) results in a circular motion in the transverse (x,y) plane (assuming that the light propagates along the z-axis) with angular frequency co and radius:where E is the peak laser electric field. In the presence of the Coulomb potential (z.e., electronic- nuclear attraction) U = — Ze7 / r, the effective electron-nucleus potential can be obtained by using the Kaptiza method, where the slow motion of the electron in the Coulomb field and fast motion in the laser field are separated. The resulting effective potential in (1+1) dimensions is thenwhere (F2) is the Lorentz force averaged over the fast motion. The second and third terms on the right-hand side of the above formula represent the ponderomotive energy, i.e., the time-averaged energy of the electron’s harmonic motion. After a straightforward generalization to the 3D case, the effective electron-nucleus potential becomes:where θ is the angle between the radius vector and the direction in which the laser field propagates, and is the second Legendre polynomial this potentialexhibits strong attraction in addition to the Coulomb force, and leads to an electron cloud squeezed along the directions perpendicular to the direction of propagating light.

[0048] At this angle and in this regard, for large (i.e., non-perturbative) values of rc, the interatomic potential becomes strongly attractive, and the size of the molecule shrinks. This is analogous to what happens in muonic molecules, but the underlying mechanism is different. The parameter rcis large for moderately intense, infrared laser pulses having circular polarization. For example, rc~ la.u. for a laser pulse with a wavelength of 800nm and peak intensity of 1010W / cm2. This conveniently places the large-rcregime of the theory in the infrared band of the electromagnetic spectrum for embodiments, which is the characteristic band of emission for modem femtosecond laser amplifier and oscillator technology. For a consistent value of the laser intensity, rccan be increased by increasing the wavelength. For a consistent value of the wavelength, rccan be increased by increasing the peak intensity.

[0049] Bicircular laser beams: A tuned bicircular laser beams can enhance the electron screening effects in molecules, as explained below. Tn a bicircular beam, the fundamental frequency of the circularly polarized laser beam is combined with its second harmonic, which can have the same or opposite circular polarization. If both circular polarizations are the same (opposite), we have a corotating (counter-rotating) bicircular laser beam. The electric field in a bicircular laser beam propagating along the z-axis has the following formwhere the co-rotating (counter-rotating) beam with frequency 2 ω and relative amplitude P corresponds to the upper (lower) sign. With this definition, the peak electric field does not depend on P and is equal to Eo, and the intensity averaged over the cycle is given bywhere Iois the intensity of a single frequency laser with peak field Eo. Assuming that the frequency co (and of course 2co) is large compared to the level spacing in an atom, the Kaptiza effective potential can be easily computed. The potential does not depend on whether the beams are co-rotating or counter-rotating, and is given by whereThis potential is the sum of the effective potentials generated by the two circularly polarized beams with frequencies co and 2co. At high frequency co, the bicircular laser field thus does not offer an advantage over a single circularly polarized beam. Once the frequency co is not large compared to atomic transition frequencies, this situation changes quite dramatically. In the classical approximation, the trajectory of electron can be found by solving classical equations of motion in the sum of electric field and the static electric field created by the ions in the molecule. In this case the bicircular field can be tuned to produce the electron trajectory localized in between the ions.

[0050] Azimuthally polarized field: to evaluate the effective potential acting on electrons in an atom placed in a high-frequency cylindrical vector laser beam, it is helpful to know the electric field in this beam. One looks for the axially symmetric, beam-like solutions to Maxwell equations in the vacuum that lead to the Helmholtz equation of the formwhere z is the coordinate along the beam axis, r is the radial coordinate, w is the laser frequency, and is the unit vector along the azimuthal direction. Under the slowly varying envelope approximation,

[0051] The corresponding solution is known as the azimuthally polarized vector Bessel-Gauss beam solution and has the following form:interaction of an atom with the laser beam, the vector Bessel-Gauss solution at the beam waist can be approximated by

[0052] The effect of this electric field on an atom is of interest. Thus, r « w can be assumed and the exponent can be replaced by unity. Applying the Kapitza method, the electric field at high frequency to leads to the following effective potential acting on electrons in an atom

[0053] This potential is quite remarkable, because at high intensities t becomes a harmonic oscillator potentialwith an effective frequency

[0054] The average size of the electron wavefunction in the ground state of this oscillator potential iswhich is about five times smaller than the size of the hydrogen atom. The vector Bessel-Gauss beam can thus be used to greatly enhance the effects of Coulomb screening on nuclear fusion.EXAMPLE FUSION SYSTEMS

[0057] A fusion system uses optical control to manipulate the quantum state of a fluid fuel (e.g, hydrogen, hydrogen deuteride, deuterium, deuterium-tritium, water, orl7O-heavy water, etc.) such that spontaneous fusion occurs "via tunneling with sufficient probability to generate a meaningful number of fusion reactions that generate more energy than is used to configure and maintain the system. Generally, a pulsed azimuthally polarized vector Laguerre-Gauss or Bessel-Gauss beam, circularly polarized beam, or bicircular beam (the “control beam”) excites fuel molecules (e.g, hydrogen, hydrogen deuteride, deuterium, deuterium-tritium, water,17O-heavy or water, etc.) to encourage fusion via tunneling through the Coulomb barrier, by manipulating the quantum state of electrons in molecules to increase Coulomb screening. The described fusion system may operate at low (e.g, ambient or below ambient) temperatures or otherwise decouple regions of high and low temperature by thermalizing fast-spectrum neutrons, produced in a reaction chamber at low temperature, with a spatially non-connected (or thermally insulated) molten salt loop and / or light / heavy water coolant / moderator and heat exchanger. Fusion reactors according to the described principles may have a relatively compact size and shape. The described concepts, structures, and techniques enable construction of robust sources of fusion power using fabrication techniques which are relatively simple compared with prior art fusion reactor fabrication techniques. Furthermore, the described concepts, structures, and techniques can use modular components that scale well toward commercialization.

[0058] FIG. 1 illustrates a one embodiment of an ultrafast laser architecture that can drive a viable fusion reaction with quantum control that can be represented on a first-order Poincare sphere. In the embodiment shown, the ultrafast laser architecture includes a quarter-wave plate with its axes at ±45° to the polarization axis of the beam is placed in the path of either beamline of a two-beam interferometer. For example, the quarter-wave plate may be placed in the VUV arm (121nm) of an interferometer (option 1), corresponding to applying a circularly polarized pump pulse in the VUV. One or more quarter-wave plates at different angles can be placed in the beam path before splitting into each arm of the interferometer (option 2), so that both the beams in the interferometer (pump and control) have circular polarization, or the bichromatic control can have a circular-linear polarization structure, in which the control pulse is linearly polarized. Various combinations can be envisioned in which the ability to apply a circularly polarized pulse (either left- or right-handed) via either or both the pump and / or control pulses is achieved using a quarter-wave plate, or another suitable method for creating circularly polarized light from a linearly polarized beam. Different handedness of the circularly polarized light beams may be converted to one another using a halfwave plate.

[0059] Higher photon energies of circularly polarized light, such as in the extreme ultraviolet(EUV) or soft X-ray regime can be made by, for example in FIG. 1, focusing the third and first harmonic into the noble gas cell after having passed them through quarter-wave plates oriented respectively at ±45° to the polarization axis of each beam, such that they are counter-rotating with circular polarization relative to one another (option 3). This enables high-harmonic generation (HHG) in which the output harmonics are of circular polarization and used accordingly as a pump pulse. Other embodiments of providing the functionality of FIG. 1 can be envisioned in which a circularly polarized pump pulse of a different wavelength and a linearly polarized control pulse are achieved to impinge on a sample of fluid fuel, to accelerate the rate of spontaneous fusion by the mechanism described above.

[0060] Using bichromatic fields, a circularly polarized pump pulse in the DUV, VUV, EUV, or soft X-ray band can be made to impinge on a sample of fluid fuel to accelerate fusion according to the mechanism described in the attached. The bichromatic fields can further be used to achieve a bichromatic pump-control scheme, in which the circularly polarized pump pulse is created using two colors present in the setup, such as the first and third harmonics. They are made to counterrotate relative to one other with circular polarization and focused into a noble gas cell (option 3). Residual of the fundamental, or another harmonic, is linearly polarized and used for further control of thesystem. Finally, existing commercial HHG sources can be modified to emit circularly polarized pump pulses which are combined with a linearly polarized residual of the fundamental frequency. Linear optical elements such as a quarter-wave plate can be used to produce circularly polarized, high-frequency pulses according to the various methods described above.

[0061] As described above, Coulomb screening and acceleration of the spontaneous fusion reaction rate is effective for the16O(p, y)17F fusion reaction taking place in a fluid fuel of water. Since17F is a p+ emitter, the energy of this fusion product can be converted to electricity using a combination of p+- and n— type semiconductors, such as a doped p-n diode made of crystalline silicon. The width of the semiconductor material is tuned to the penetration depth of the 0+ particles emitted from, e.g.,17F, which is determined by their energies.

[0062] FIG. 2 illustrates one embodiment of a fusion system that can provide quantum control that is represented on a higher-order Poincare sphere. In the embodiment shown, the fusion system includes a laser source 202 and a reactor 218. Various optical components are used to modify the beam generated by the laser source 202 and direct the resulting beam into the reactor 218. An energy extractor 220 is disposed around at least a portion of the reactor 218 to collect energy generated by fusion reactions. In other embodiments, the fusion system may include different or additional elements. Furthermore, various elements may operate in a different manner than described. The described fusion system is provided by way of example of the broader principles it embodies. For example, although only a single reactor 218 is shown, a single laser source 202 may emit a pulsed beam which is split and modified so as to enter multiple reactor assemblies.

[0063] The laser source 202 generates a pulsed optical beam having a (e.g., fundamental) frequency. In one embodiment, the laser source 202 includes a ffee-space Yb cavity laser oscillator. The output of the amplifier may be a 0.5nJ pulse with a 1GHz repetition rate, 140fs pulse duration, a central wavelength of 1030nm, and vertical polarization. In other embodiments, laser sources 202 of other types with different frequencies may be used.

[0064] An optical assembly modifies the pulsed beam generated by the laser source 202 and directs the modified pulsed beam into the reactor 218. In the embodiment shown in FIG. 3, the optical assembly includes a Galilean beam expander 204 and a half-wave plate 206, configured to rotate the expanded beam such that it has horizontal polarization. In embodiments, the half-wave 206 plate may be fabricated using liquid crystal technology such that the beam rotation is dynamically controllable using a computer-defined voltage. The expanded, horizontally polarized beam is passed through a radial polarizer 208 oriented orthogonally to the beam polarization, inorder to generate a pulsed azimuthally polarized vector beam with a Laguerre-Gauss wavefront (also referred to as a donut beam). The pulsed azimuthally polarized vector beam may then be passed through a flat axicon 210 configured to shape the wavefront into a Bessel-Gauss beam. The pulsed, azimuthally polarized vector Bessel-Gauss beam is directed towards and focused into the reactor 218, through an optical port 216, by an ultrafast mirror 212 and an objective lens 214 (e.g., a microscope objective with a working distance of 6mm). The reactor 218 includes a fluid fuel, such as deuterium gas contained in a high-pressure (~100psi) steel alloy gas cell.

[0065] In other embodiments, a supersonic molecular beam is used to achieve high number density of a fluid fuel. In other embodiments, a hollow-core fiber is used to achieve a large interaction volume with molecules of the fluid fuel. An optical port 216 couples the laser beam into the reaction chamber. The optical port 216 may be a sapphire window that is z-cut so that the c-axis of the crystal is parallel with the optical axis, removing bifringence effects on transmitted light. The pulsed azimuthally polarized vector Bessel-Gauss beam may be focused by the microscope objective to the beam’s diffraction limit. In embodiments, a peak intensity of ~22 GW / cm2or higher is achieved and depends on the input pulse energy from the drive oscillator (e.g., InJ or higher). The focused, pulsed azimuthally polarized vector Bessel-Gauss beam then interacts with molecules of the fuel in the reactor 218 to execute the Poincare engineering control protocol. This generates a flux of fusion fast-spectrum neutrons which are thermalized and converted to electricity via energy extractors.

[0066] The beam may be endowed with azimuthal polarization using a variety of optical plate choices and configurations that function effectively as (or similarly to) a radial polarizer 208. In one embodiment, an S-plate is used. Alternatively, a Z-polarizer, vortex plate, or variable spiral wave plate may be used. A variable spiral wave plate includes (z) a quarter-wave plate rotated by either 45° or -45° relative to the polarization of the pulsed (e.g., fundamental) frequency beam (to generate a pulsed beam having circular polarization) and (z’z) a Q-plate, a bifringent wave plate fabricated using liquid crystal technology with an inhomogeneous patterned distribution of the local optical axis in the transverse plane. The Q-plate is then configured to produce a pulsed beam with azimuthal polarization from the circularly polarized pulsed beam by a change in the applied bias, which may vary in time according to a computer-defined control sequence.

[0067] The beam wavefront may be shaped using a variety of optical plate choices and configurations that function effectively as (or similarly to) a flat axicon 210. In one embodiment, an annular slit is used to generate a Bessel-Gauss wavefront from the Laguerre-Gauss wavefront.Additionally or alternatively, the topological charge (e.g., a semi-integer between -100 and 100 characterizing the fast-axis pattern on radial-polarizing elements of the optical assembly) may be altered to generate higher-order Laguerre-Gauss modes, which may be further combined with additional wavefront-shaping techniques in order to generate higher-order Bessel beams.

[0068] In the case of a voltage-defined pulse shape, closed-loop learning control can then be deployed to adjust (e.g., optimize) the fusion system. A measurement of the fusion yield is performed for a collection of random pulse shapes. A collection of pulse shapes having a large fusion yield for a constant pulse energy, relative to a randomly chosen initial set of pulse shapes, is used to execute a search for an optimal pulse shape using a pattern-recognition algorithm. In one embodiment, this corresponds to moving along the higher-order Poincare sphere(s) by altering the pattern of the Q-plate’s local optical axis via voltage control of the liquid crystal assembly, and / or by altering the rotation angle of the liquid crystal half-wave plate. Any suitable observable indicative of the amount of fusion occurring may be used to drive the search. For example, a3He neutron detector may be used in the case of deuterium-based fusion, or two scintillation y detectors may be used, configured in coincidence mode, in the case of water-based fusion. In this regard, higher-order Bessel beams can be effectively sampled without manual plate replacement (e.g., while the reactor is operating). Additionally, the computer can dynamically alter the reactor output by moving along different regions of the higher-order Poincare sphere(s) depending on electrical and / or heat loads defined at a user endpoint.

[0069] The fusion reaction occurs inside a fuel cell (e.g., a gas cell) of the reactor 218. The fuel cell may be comprised of aluminum or another suitable material with low neutron-capture cross section. The quantum control beam is directed into the fuel cell through an optical port 216 by an objective lens 214. The optical port 216 may be fabricated using sapphire, MgFz, quartz, NaCl, zinc selenide, titanium dioxide, CVD diamond, or any other suitable material. The fuel cell may include a quartz spectroscopy cuvette containing liquid water or17O-heavy water.

[0070] One or more energy extractors 220 are positioned in or around the reactor assembly to extract energy from fusion products generated by the fusion reaction in the fuel cell. In one embodiment, the energy extractors 220 include a molten salt loop (e.g., fluoride salts, chloride salts, LiF / 6LiF / 7LiF, UF4, TI1F4, etc? and a heat exchanger, which are used to respectively thermalize fusion fast-spectrum neutrons and drive a turbine, producing electricity. In other embodiments, the energy extractors 220 may comprise light or heavy water, which may serve as reactor coolant and / or neutron moderator. Alternatively, the neutron moderator may be graphite and the coolant is heliumgas. In yet other embodiments, the reactor coolant is liquid metal (e.g., lead-bismuth eutectic moderated with beryllium, sodium, etc.). In embodiments, a neutron shield 222 (e.g, Shieldwerx- 237, graphite, etc?) is utilized to protect the optical assembly and laser source 202 from fusion neutrons. An ultrafast mirror 212 may direct the pulsed, azimuthally polarized vector Bessel-Gauss beam into the reaction chamber -via the objective lens 214 (e.g., a microscope objective) at a suitable angle or through a maze-like design (e.g., the beam path is directed along at least one right-angle in 3D space before coupling to the reaction chamber -via the optical port) which incorporates neutron shielding material to reduce (e.g, minimize) neutron activation of high-value or high-sensitivity components such as the laser source 202 and the topologically charged optical plates.

[0071] FIG. 3 A illustrates a representation of an optical control beam produced by the embodiment of FIG. 1 on a first-order Poincare sphere. FIG, 3B illustrates a representation of an optical control beam generated by the embodiment of FIG. 1 represented on a higher-order Poincare sphere. One skilled in the art will appreciate that embodiments represented on the higher-order Poincare sphere enable relatively greater control over electron motion in atoms and molecules, and therefore, can be used to screen the Coulomb barrier and accelerate fusion rates over prior art techniques, especially those which utilize (e.g., only) the laser pulse energy, duration, and focus (e.g. , inertial confinement fusion) to create a thermonuclear plasma in which fusion reactions occur by stochastic high-energy collisions alone.

[0072] As compared to prior art fusion techniques in which confinement of atomic nuclei must be maintained by external potentials (e.g., in magnetic confinement fusion approaches), in the described fusion reactor, confinement is a passive consequence of the electronic structure of water or hydrogen, which provides the screening to stabilize nuclear wavefunctions at enlarged configuration space densities.

[0073] FIG. 4 illustrates energy as a function of separation of particles. Specifically, FIG. 4 illustrates the total electronic energy of a (hydrogen) molecule under control of a chiral optical field having an rcparameter value of unity. The energy is computed by considering t / eff as the one- electron potential in a bespoke electronic structure code with finite basis set. Similarly to muonic molecules, the chemical binding energy of the molecule under chiral control is significantly enlarged (above 0.5keV), and the chemical bond length is reduced (15pm).

[0074] One skilled in the art will appreciate that the electronic structure illustrated in FIG. 4 is highly similar to the structure of muonic molecules, along the aims discussedabove. Using the potential fit in FIG. 4, the WKB computation yields an enhancement of the fusion rate relative to theusual hydrogen molecule by 66 orders of magnitude. Using Koonin and Nauenberg’s estimate for the usual hydrogen molecule fusion rate of ~10"64s"*, the fusion reaction system disclosed herein can achieve a fusion rate of ~ 100s"1. With this fusion rate acceleration under ultrafast optical control with a pulsed, chiral laser field in the infrared band of the spectrum it is possible to achieve a fusion wall-plug Q-factor (net energy gain) of around ten for various embodiments, such as those making use of liquid water as a fuel source.

[0075] As compared to prior art fusion techniques in which confinement of atomic nuclei must be maintained by external potentials (e.g, in magnetic confinement fusion approaches), in the described fusion reactor, confinement is a passive consequence of the electronic structure of water, which provides the screening to stabilize nuclear wavefunctions at enlarged configuration space densities.

[0076] Depending on which isotopologue of hydrogen is used, fusion can take place between protons, hydrogen and deuterium, deuterium and deuterium, or deuterium and tritium, etc. Depending on which isotopologue of water is used, fusion can occur between16O and p,17O and p, etc.

[0077] FIG. 5 illustrates one embodiment of a fusion system in which quantum control is used to mediate fusion reactions using an isotopologue of water as the fuel. In the embodiment shown, the fusion system includes a laser source 510 and a reactor 540. Various optical components are used to modify the beam generated by the laser source 510 and direct the resulting beam into the reactor 540. An energy extractor 550 is disposed around at least a portion of the reactor 540 to collect energy generated by fusion reactions. In other embodiments, the fusion system may include different or additional elements. Furthermore, various elements may operate in a different manner than described. The described fusion system is provided by way of example of the broader principles it embodies. For example, although only a single reactor 540 is shown, a single laser source may emit a pulsed beam which is split and modified so as to enter multiple reactor assemblies.

[0078] The laser source 510 generates a pulsed optical beam having a fundamental frequency. In one embodiment, the laser source 510 includes a Ti:Sapphire femtosecond laser amplifier. The output of the amplifier may be a >5mJ pulse with a 1kHz repetition rate, <100fs pulse duration, and a central wavelength of 800nm. In other embodiments, laser sources 510 of other types with different frequencies may be used.

[0079] An optical assembly modifies the pulsed beam generated by the laser source 510 and directs the modified pulsed beam into the reactor. In the embodiment shown in FIG. 5, the opticalassembly includes a quarter-wave plate 520 rotated by either 45 degrees or -45 degrees relative to the polarization of the fundamental frequency beam, to generate a pulsed beam having circular polarization (z.e., a chiral pulsed field). The optical assembly may also include one or more lenses 530 (e.g., a lm lens), that focus and alter the peak intensity of the circularly polarized pulsed beam as it enters the reactor 540. The pulsed beam interacts with molecules of the fuel in the reactor 540 to execute the control protocol. The distances between the lens(es), laser source, and the reactor 540 may be chosen so as to optimize the control protocol for laser spot size at the fluid fuel target (e.g., a loose focusing geometry such that the laser field interacts with a large number of molecules) concurrently with the laser peak intensity (e.g., moderate intensities so as to lie above a viability threshold while avoiding multiphoton processes dominating the interaction between the molecule and laser radiation) as determined by the pulse energy and wavelength.

[0080] For example, for fusion reaction systems making use of laser sources having lower pulse energies (e.g., a femtosecond Yb laser oscillator with a —nJ pulse energy emitting at 1030nm), the pulse may be focused to the diffraction limit at the point of contact with fuel in the reactor 540. In this example, to reach peak intensities relevant for the disclosed fusion process (e.g., a few 1010W / cm2), a high peak oscillator power is used and the beam is expanded before applying a quarterwave plate 520. By filling the entrance pupil of a focusing objective having a relatively short working distance (e.g., a few mm) the spot size at the point of contact with fluid fuel can then be reduced to a few microns. This compact focusing geometry opens the door for use of small and relatively inexpensive laser oscillators (as opposed to chirped pulse amplifiers) to achieve fusion reactions according to the disclosed method, in various field scenarios where the available space and laser power consumption are limited.

[0081] FIG. 6 illustrates one embodiment of a fusion system using bicircular fields incident on fluid fuel. The illustrated fusion system uses variations on a circularly polarized control field, such as a bicircular (bichromatic, counterrotating) field. In this example, the a laser source 610 (e.g., a Ti:Sapphire laser, Z=770nm, ~27fs, 1.5mJ) generates a fundamental beam that is passed through an in-line optical integration module including a lens 604 (e.g., f=500mm), a BBO crystal 606, a pair of calcite plates 608, and an achromatic quarter waveplate 610. In one embodiment, a portion of the energy of the linear s-polarized fundamental pulse is converted into a perpendicular p-polarized second harmonic (SH) field (e.g., X=394nm) in a beta-phase barium borate crystal 606 (e.g., BBO, 0.2 mm, cutting angle 29.2° for type I phase matching). The beam passes through the pair of calcite plates 608 (e.g., 55° cut with respect to the optical axis, 1mm thick, AR coated) which pre-compensate for group delays induced by normally dispersive optics down the beam path. The SH pulse precedes the fundamental by At_BC~600 fs as they emerge from the calcite plate pair 608.

[0082] This trichromatic delay, At_BC, is compensated for when the bichromatic field passes through the quarter waveplate 610 and other optical components (e.g., the fuel cell window 612), so the fundamental and SH pulses overlap temporally. The exact timing can be tuned by rotating the calcite plates 608 around the axis perpendicular to the optical table. Rotating each plate within ±10° tunes its temporal compensation in the range of 145— 300fs, so the calcite plate pair 608 supports delay range of 290— 600fs. The calcite plate pair 608 may be positioned with inversely rotated geometry and inward pointing extraordinary axis (e.g., 55° tilt from the surface normal-vector) to cancel out any beam shifts caused by Snell’s law and birefringent walk-offs. Thus, the joint bichromatic focal spot is unperturbed by the rotation of the pair of calcite plates 608.

[0083] The polarizations of the linear s-polarized fundamental and perpendicular p-polarized SH can be converted to counterrotating circular polarization by a single achromatic quarter waveplate 610 for the two spectral components (e.g., k=4 for 310 nm— 1100 nm, the waveplate retardation being 0.258 and 0.240 waves for wavelengths 770 nm and 394 nm, respectively). Once the polarizations are set to counterrotating circular polarizations, stress-induced birefringence or tilting of optical element down the line may reduce the pump ellipticity. Therefore, then entrance window 612 to the fuel cell 614 (e.g., 2 mm fused silica) can be mounted with uniform stress distribution and perpendicular to the incoming beam. Bicircular pulses are focused into a fluid-filled fiber 616 (e.g., a photonic bandgap fiber, a hollow-core fiber, or a photonic crystal fiber). The fiber 616 contains fluid fuel 618, such as deuterium gas.

[0084] In the co-rotating case, a dichroic half waveplate rotates one of either the fundamental or the second harmonic to have the same polarization before passing through the calcite plate 608.

[0085] Energy extractors 620 are disposed around the fluid-filled fiber 616. In one embodiment, the energy extractors 620 include a molten salt loop containing a fluoride or chloride molten salt. It should be appreciated that various embodiments of a bicircular field may be employed, which are illustrated in the insert of FIG. 6. For example, while a bicircular field of the laser fundamental and its second harmonic is described above for achieving control over the fusion process, other combinations of the fundamental beam (having a frequency of co) or one or more of its harmonics may be employed, such as for example co-3co, co-4co, 2(o-3co, 3co-4co, 2co-5co, etc. It should be appreciated that various techniques for generating the associated higher harmonics of the fundamental beam (such as, e.g., third harmonic generation, fourth harmonic generation, fifthharmonic generation, sum-frequency generation, etc.) as well as known techniques for compensating the associated group delays and other beam shifts associated with using other combinations of fundamental or harmonics in the above described apparatus, may be used to achieve bicircular control over the fusion process.ALTERNATIVE OPTICAL CONFIGURATIONS

[0086] The Poincare engineering optical control protocol set forth above can be realized by repurposing alternative ultrafast pulsed sources. It should be emphasized that there are many possible embodiments, configurations, and choices of center wavelength which can result in the optical control protocol described. Various example alternatives are described below.

[0087] In embodiments, the laser source includes a Tm femtosecond fiber laser amplifier. The output of the amplifier may be a 3mJ pulse with a 50kHz repetition rate, <200fs pulse duration, and a central wavelength of 1950nm.

[0088] In embodiments, the laser source includes a Tm femtosecond fiber laser amplifier. The output of the amplifier may be a lOOpJ pulse with a 150kHz repetition rate, <400fs pulse duration, and a central wavelength of 1980nm.

[0089] In embodiments, the laser source includes an Yb femtosecond fiber laser amplifier. The output of the amplifier may be a 3mJ pulse with a 2MHz repetition rate, <350fs pulse duration, and a central wavelength of 1030nm.

[0090] In embodiments, the laser source includes a free-space Yb cavity laser amplifier. The output of the amplifier may be a 20mJ pulse with a 40MHz repetition rate, <1 ,5ps pulse duration, and a central wavelength of 1030nm.

[0091] In embodiments, the laser source includes a free-space Yb cavity laser oscillator. The output of the amplifier may be a 0.5nJ pulse with a 1GHz repetition rate, 140fs pulse duration, and a central wavelength of 1030nm.

[0092] In embodiments, the laser source includes an optical parametric amplifier. The output of the amplifier may be a 400pJ pulse with a 2MHz repetition rate, 300fs pulse duration, and a central wavelength between 1350nm-2000nm and / or 2100nm-4500nm and / or 240nm.

[0093] In embodiments, the laser source includes a nanosecond laser, such as a neodymium- doped yttrium lithium fluoride (Nd:YLF) laser or a neodymium-doped yttrium aluminum garnet(Nd:YAG). The output of the laser source may be a 250mJ pulse with a 20Hz repetition rate, 8ns pulse duration, and a central wavelength of 1064nm.

[0094] In embodiments, the laser source includes frequency-doubled light from an infrared pulsed laser source (e.g., frequency-doubled green light having a central wavelength of 515nm, from an Yb laser amplifier). In embodiments, this is achieved using a / ?-barium borate (BBO) nonlinear crystal configured for Type I SHG (0=23.4°, 0=90°).

[0095] In embodiments, the laser source includes a SESAM mode-locked ultrafast think-disk laser oscillator. The output of the oscillator may be a lOOpJ pulse with 5,5MHz repetition rate, 852 fs pulse duration, and a central wavelength of 1030nm.

[0096] In embodiments, the chiral pulsed beam may have an elliptical polarization (z'.e., the quarter-wave plate is rotated by an angle other than +\- 45 degrees relative to the polarization of the pulsed input beam).EXAMPLE LASER PARAMETERS OF INTEREST

[0097] The control protocol may additionally make use of a selection procedure for the frequency and intensity of control pulses to set the value of the rcparameter, which is desired to lie above a certain threshold corresponding to a desired number of fusion reactions in the fluid fuel. The value of rcis preferably chosen such that the energy required to operate the fusion reactor is less than the energy produced and captured by the reactor. Table 1 illuminates various rcparameter values (provided in a.u.) for three exemplary wavelengths (corresponding by row to exemplary embodiments in Ti: Sapphire, Yb, and Tm laser amplifiers, respectively) disclosed in the present invention as a function of peak intensity.Table 1

[0098] It should be understood that the present disclosure seeks to cover a broad range of infrared pulsed laser architectures which make use of a chiral (circularly or elliptically polarized)laser pulse to control electron motion in a fluid fuel (e.g., liquid water, hydrogen, hydrogen deuteride, or deuterium, etc.) such that the intramolecular fusion rate exceeds a viability threshold.

[0099] The control protocol may additionally make use of a selection procedure for the frequency and intensity of control pulses to set the value of the rpparameter, which is desired to lie below a certain threshold corresponding to a desired number of fusion reactions in the fluid fuel, according to electron cloud Coulomb screening effects. The value of rpis preferably chosen such that the energy used (e.g. , required) to operate the fusion reactor is less than the energy produced and captured by the reactor. Table 2 enumerates various rpparameter values (provided in a.u.) for three exemplary wavelengths (corresponding by row to exemplary embodiments in Ti:Sapphire, Yb, and Tm laser amplifiers, respectively) disclosed in the present disclosure as a function of peak intensity.Table 2

[0100] It should be understood that the present disclosure includes a broad range of infrared pulsed laser architectures which make use of an azimuthally polarized vector Bessel-Gauss pulsed beam to control electron motion in a fluid fuel (e.g. , hydrogen, hydrogen deuteride, deuterium, deuterium-tritium, or liquid water, etc.) such that the intramolecular fusion rate exceeds a viability threshold according to the principles set out in

[0003] ,EXAMPLE METHODS OF INDUCING FUSION

[0101] FIG. 7 illustrates an example method 700 for inducing fusion in target molecules with a pulsed beam, according to one embodiment. In the embodiment shown, the method 700 begins by selecting 710 parameters of the pulsed beam (e.g., an infrared pulsed beam) to achieve a desired rcfor the target molecules. The parameters can include the wavelength, peak intensity, or both and can be selected 710 according to the theory and principles described above. A source of pulsed beams isconfigured 720 according to the selected parameters and the pulsed beam is used to irradiate 730 the target molecules. The pulsed beam may be modified to impart circular or elliptical polarization between being emitted by the beam source and hitting the target molecules (e.g., using a quarterwave plate or other optical component(s) as described previously). The irradiation 730 of the target molecules with the modified beam causes the probability of fusion of components of the target molecules to exceed a threshold (e.g., a viability threshold). In one embodiment, the modified pulsed beam alters at least one of a chemical binding energy, or a chemical bond length, the alteration performed by having the pulsed beam excite electrons in the target molecules to achieve quantum state control over the target molecules.

[0102] FIG. 8 illustrates an example method 800 for inducing fusion in target molecules with a pulsed beam, according to one embodiment. In the embodiment shown, the method 800 begins by selecting 810 parameters of the pulsed beam (e.g., an infrared pulsed beam) to achieve a desired rpfor the target molecules. The parameters can include the wavelength, peak intensity, or both and can be selected 810 according to the theory and principles described above. A source of pulsed beams is configured 820 according to the selected parameters and the pulsed beam is used to irradiate 830 the target molecules. The pulsed beam may be modified to impart azimuthal polarization and a Bessel- Gauss wavefront between being emitted by the beam source and hitting the target molecules (e.g., using an S -plate and a flat axicon or other optical component(s) as described previously). The irradiation 830 of the target molecules with the modified beam causes the probability of fusion of components of the target molecules to exceed a threshold (e.g., a viability threshold). In one embodiment, the modified pulsed beam alters at least one of a chemical binding energy or a chemical bond length, the alteration performed by having the pulsed beam excite electrons in the target molecules to achieve quantum state control over the target molecules.

[0103] FIG. 9 illustrates experimental observation of an accelerated fusion rate, according to one embodiment. Using the results derived in Quantum control examples, the in situ fusion rate in watera factor of 5. In the results shown, this is achieved using an optical parametric amplifier emitting femtosecond pulses having a center wavelength of 240nm, with a duration of 60fs, a peak intensity of 1.9GW / cm2, and a repetition rate of 1kHz. The interaction length is approximately 1mm, and the laser spot diameter at the target is approximately 0.7mm. The detector area is approximately 51% of the total 4π solid angle. These pulse parameters correspond to an rcvalue of approximately 0.2au(which is 1 / 5 the Bohr radius). The fusion rate is measured by counting gamma-gamma coincidences from the beta decay of a product17F nucleus, with 2” by 4” lead shielding of the background radiation. At the expected peak, a coincident signal above background is observed with confidence interval >95%.

[0104] FIG. 10 is a spectrum of the product nucleus of17O+p fusion,18F. The motivation for choosing to perform the above-described screening control protocols in17O-enriched heavy water fuel is that, by stabilizing the chemical bond between17O and p by -IkeV, as is possible per the quantum chemistry calculations shown in FIG. 4, the system can be brought on resonance with a 1 " state in the product nucleus,18F. Threshold resonances in nuclear fusion reactions have been shown to accelerate in situ nuclear fusion rates by at least four orders of magnitude.ADDITIONAL CONSIDERATIONS

[0105] As used herein, any reference to “one embodiment” or “an embodiment” means that a particular element, feature, or structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. Similarly, use of “a” or “an” preceding an element or component is done merely for convenience. This description should be understood to mean that one or more of the elements or components are present unless it is obvious that it is meant otherwise.

[0106] Where values are described as “approximate” or “substantially” (or their derivatives), such values should be construed as accurate + / - 10% unless another meaning is apparent from the context. From example, “approximately ten” should be understood to mean “in a range from nine to eleven.”

[0107] As used herein, the terms “comprises," “comprising,” “includes,” “including,” “has,” or “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0108] Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for a system and a process for optically controlled fusion. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the described subject matter is not limited to the precise construction and components disclosed. The scope of protection should be limited only by the following claims.

Claims

CLAIMSWhat is claimed is:

1. A fusion system comprising: an optical source that generates a pulsed input laser beam; a reactor assembly configured to contain a fluid fuel in a reaction chamber, the reactor assembly having an input optical port that optically couples the reaction chamber to an exterior surface of the reactor assembly; an optical assembly that generates, from the pulsed input laser beam, a control beam and directs the control beam into the reaction chamber through the optical input port, wherein the control beam is configured to modify a quantum state of fuel particles in the reaction chamber according to a quantum control protocol such that fuel particles in the modified quantum state have a fusion probability exceeding a viability threshold; and an energy extractor configured to extract energy generated by fusion reactions involving the fuel particles in the modified quantum state from the reactor assembly.

2. The fusion system of claim 1, wherein the optical assembly comprises at least two of: a first optical component configured to expand the input beam; a second optical component configured to rotate the beam’s linear polarization; a third optical component configured to generate, from the input beam, a modified optical beam by polarization control; a fourth optical component configured to generate, from the modified optical beam, a beam with a further modified wavefront; and a fifth optical component configured to focus the further modified optical beam.

3. The fusion system of claim 2, wherein the first optical component is a Galilean beam expander, the second optical component is a half-wave plate, the third optical component is a radial polarizer, the fourth optical component is a flat axicon, and the fifth optical component is a microscope objective.

4. The fusion system of claim 2 or claim 3, wherein the third optical component is one of either an S-plate, a Z-polarizer, a vortex plate, or a variable spiral plate.

5. The fusion system of claim 4, wherein the variable spiral plate comprises a quarterwave plate and a Q-plate, the Q-plate being configured to produce a pulsed beam with azimuthal polarization from a circularly polarized pulsed beam responsive to a change in the applied bias, wherein the applied bias varies over time according to the quantum control protocol.

6. The fusion system plate of claim 2 or claim 3, wherein the second optical component is a half-wave plate and an angle of rotation of the half-wave plate is configured using a patternrecognition model.

7. The fusion system of claim 1, claim 2, or claim 3, wherein the input pulsed optical beam has a wavelength of approximately 1030nm, and wherein modifying the state of the fuel particles comprises exciting electrons of the fuel particles such that at least one of a chemical binding energy of the fuel particles or a chemical bond length of the fuel particles are respectively increased or decreased.

8. The fusion system of claim 1, claim 2, or claim 3, wherein the input optical beam has a wavelength of approximately 800nm, approximately 1350nm-2000nm, or approximately 2100nm- 4500nm.

9. The fusion system of claim 1, claim 2, or claim 3, wherein the optical source is an infrared laser source.

10. The fusion system of claim 9, wherein the infrared laser source is an Ytterbium femtosecond oscillator.1 1. The fusion system of claim 1 , claim 2, or claim 3, wherein the optical source generates pulses having a duration between approximately 140fs and approximately 8ns.

12. The fusion system of claim 1, claim 2, or claim 3, wherein the fluid fuel comprises an isotopologue of water, deuterium gas (D2), hydrogen deuteride gas (HD), or deuterium-tritium gas (DT).

13. The fusion system of claim 1, claim 2, or claim 3, wherein the fluid fuel comprises17O-heavy water (H217O).

14. The fusion system of claim 1, claim 2, or claim 3, wherein the control beam is an azimuthally polarized vector Laguerre-Gauss or Bessel-Gauss pulsed beam, a circularly polarized scalar pulsed beam, or a bicircular beam.

15. The fusion system of claim 1, claim 2, or claim 3, wherein the energy extractor comprises at least one of a scintillator and semiconductor pair, an electronic-grade single-crystal diamond, a heavy metal perovskite, or a crystalline silicon.

16. The fusion system of claim 1, claim 2, or claim 3, wherein the energy extractor comprises a heat exchanger coupled to at least one of a molten salt neutron moderator and coolant loop, a liquid metal neutron moderator and coolant loop, a light or heavy water neutron moderator and coolant loop, or a graphite neutron moderator and helium coolant loop.

17. The fusion system of claim 1, claim 2, or claim 3, wherein fusion occurs while the reaction chamber is at a temperature between approximately zero and approximately one hundred degrees Celsius.

18. The fusion system of claim 1, wherein the control optical beam is a bicircular beam.

19. The fusion system of claim 18, wherein the optical assembly comprises: a lens; a BBO crystal; a pair of calcite plates; and an achromatic quarter waveplate.

20. A method for adjusting a fusion system comprising: selecting, according to a desired value of electron motion radius, rp, parameters for an optical beam, the parameters including a target frequency and a focusing geometry such that the optical beam has a target peak intensity, wherein rpis selected such that a fusion probability in particles of the fuel exceeds a viability threshold, wherein the viability threshold is chosen such that the energy used (e.g., required) to operate the fusion reaction system is less than the energy produced and extracted from the fusion reaction system; and configuring a laser source of the fusion system using the selected parameters.

21. A method for facilitating nuclear fusion in molecules, the method comprising: selecting at least one of a wavelength or a peak intensity of a pulsed beam such that an electron motion radius, rp, associated with target molecules results in a fusion probability above a viability threshold; configuring a source of a pulsed beam according to the selected at least one of the wavelength or the peak intensity; and irradiating the target molecules with the pulsed beam, wherein the pulsed beam is modified such that the pulsed beam has azimuthal polarization and a Bessel-Gauss wavefront when incident on the target molecules, wherein the modified pulsed beam alters at least one of a chemical binding energy or a chemical bond length, the alteration performed by having the pulsed beam excite electrons in the target molecules to achieve quantum state control over the target molecules.

22. A method for causing fusion in17O-heavy water with polarization-shaped control pulses by stabilizing a chemical bond to be closer to resonance with the 1- state in18F.

Images