WO2023158458A2

WO2023158458A2 - Fusion reactor using bichromatic optical control of quantum tunneling

Info

Publication number: WO2023158458A2
Application number: PCT/US2022/035845
Authority: WO
Inventors: Jacob Levitt; Thomas C. WEINACHT; Herschel Albert RAVITZ
Original assignee: Cortex Fusion Systems, Inc.
Priority date: 2021-07-02
Filing date: 2022-06-30
Publication date: 2023-08-24
Also published as: WO2023158458A3; EP4364167A2

Abstract

A fusion reactor uses optical pulse shaping to control a fusion reaction. A reactor assembly accepts a fluid fusion reaction fuel for energy generation, calibration, or diagnostic measurements, and provides for conversion of high-energy fusion products to current. The fusion reactor may operate in ambient conditions or at lower than ambient temperatures. The use of modular components may enable scaling for efficient commercialization.

Description

FUSION REACTOR USING BICHROMATIC OPTICAL CONTROL OF QUANTUM TUNNELING

Inventors:

Jacob Levitt Thomas C. Weinacht Herschel Albert Rabitz

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/218,146, filed July 2, 2021, which is incorporated by reference.

BACKGROUND

1. TECHNICAL FIELD

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

2. BACKGROUND INFORMATION

[0003] One of the challenges in producing a viable fusion reactor is containing the fusion fuel once the reaction is underway for sufficient time for net-positive energy to be harvested. Existing approaches to confinement include inertial confinement (IC) and magnetic confinement (MC).

[0004] In the IC approach, an incident laser or ion beam is directed on the outer layers of the fuel. This exerts an inward force sufficient to yield a high density of fusion material and contain the fusion reaction for a sufficient time to allow enough fusion reactions to occur. In the MC approach, strong magnetic fields interact with the electrical charge on the fuel so as to counteract the plasma pressure of the fuel, thus compressing the fuel for sufficient time to allow enough fusion reactions to occur. [0005] Both approaches require high temperatures and densities that complicate the net-positive production of energy. Specifically, these containment techniques use a large amount of energy, meaning the number of fusion reactions required to achieve positive energy production is relatively large. Furthermore, the high temperahires and pressures involved result in further challenges for energy harvesting and reactor lifetime. There is a need for approaches to controlling fusion reactions that are economical and can operate in conditions that are conducive to simple energy harvesting.

SUMMARY

[0006] A fusion system uses optical pulse shaping to control a fusion reaction. The fusion system may use modular components that scale well toward commercialization. The system includes a reactor assembly that accepts fluid fusion reaction fuel 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) and at moderate field intensities, enabling efficient use of optical signal manipulation with information and photonic crystal technologies. The net result is an electrical generator assembly that may be seamlessly integrated into existing electrical infrastructures.

[0007] In one embodiment, a fusion reaction system includes a laser source that generates an input beam. The fusion reaction system also includes an optical assembly that generates a first pulsed beam and a second pulsed beam using the input beam. A reaction chamber is configured to contain a fluid fuel and has first and second optical inputs and a second optical input. The first pulsed beam enters the reaction chamber through the first optical input and excites particles of the fluid fuel into an excited state. The second pulsed beam induces phase shifts to the particle in the excited state such that a fusion probability exceeds a viability threshold. An energy extractor extracts energy generated by fusion reactions from the reaction chamber.

[0008] In some embodiments, the input beam has a wavelength of approximately

605nm. The input beam may be made up of femtosecond pulses. The second pulsed beam may be a third harmonic of the input beam. The fusion reaction system may also include a first BBO crystal that generates an intermediate beam that from the input beam that is a second harmonic of the input beam and a second BBO crystal that generates a second intermediate beam that is a third-harmonic of the input beam via sum-frequency generation using the input beam and the intermediate beam, wherein the second pulsed beam is at least a portion of the second intermediate beam. The first pulsed beam may be a fifth harmonic of the input beam. [0009] The fusion reaction system may also include a second beam splitter that splits the second intermediate beam into the second pulsed beam and a third intermediate beam, a pulse shaper that modifies at least one of a phase or an amplitude of frequency components of the third intermediate beam, and a noble gas cell in which the first pulsed beam is generated via non-collinear four-wave mixing of the third intermediate beam and a portion of the input beam. The noble gas cell may include at least one of Argon or Krypton gas at a predetermined pressure. The pulse shaper may include a grating and a curved mirror that spatially separate the frequency components of the intermediate beam. The pulse shaper may also include an acousto-optic modulator configured modify the at least one of the phase or the amplitude of the frequency components.

[0010] In some embodiments, the fuel is a hydrogenic isotopologue of water. The he first pulsed beam excites water molecules into the electronic state. The

phase shifts introduced by the second pulsed beam include a set of pi phase-shift kicks. The phase shift-kicks increase a probability of a fusion event occurring due to a particle quantum tunneling through the Coulomb barrier into a continuum of fusion product channels. The fluid fuel may be a beam of gas-phase molecules or a liquid-jet of water molecules. For example, a beam of gas-phase water molecules may be used in a diagnostic/calibration mode and a liquid jet of water molecules may be used in a power-generation mode.

[0011] The fusion may occur while the reaction chamber is at a temperature between approximately zero and approximately one hundred degree Celsius. The energy extractor may generate heat from fusion products and provide the heat to drive a turbine. Additionally or alternatively, the energy extractor may include a scintillator that converts fusion products to visible light and a semi-conductor that converts the visible light into an electrical current.

[0012] 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 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, beta particles, alpha particles, helium-3, 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 the area of high-energy particle physics; and applications in the area of nuclear counter-proliferation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a block diagram of a fusion system using optical pulses, according to one embodiment.

[0014] FIG. 2 is a block diagram of the fusion reactor of FIG. 1, according to one embodiment. [0015] FIG. 3 illustrates a process for calibrating the fusion system, according to one embodiment.

[0016] FIG. 4 illustrates how fusion may occur via tunneling through the Coulomb barrier from a molecular bound state to the continuum of product translational states.

[0017] FIG. 5 illustrates a fiber bundle, showing a connection and holonomy of the base manifold, M, which is the projective Hilbert space of nuclear configurations belonging to a given electronic state, with a light-induced conical intersection that is equal to pi, according to one embodiment.

[0018] FIG. 6 is an isometric view of the electronic structure of water including a conical intersection that may be manipulated by quantum control to increase the probability of spontaneous fusion, according to one embodiment.

[0019] FIG. 7 illustrates a light-induced conical intersection in the electronic structure of water, according to one embodiment.

[0020] FIG. 8 illustrates reaction cross-sections between water and a range of light wavelengths at room temperature.

[0021] FIG. 9 illustrates a stochastic model in which a set of pi phase shifts accelerate quantum tunneling when averaged across all possible combinations of phase shifts, according to one embodiment.

[0022] FIG. 10 illustrates quantum interference patterns resulting from conical intersections on the natural electronic structure of water when the water is excited by a vacuum ultraviolet (VUV) pulse, according to one embodiment.

DETAILED DESCRIPTION

[0023] 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 or any combination of such elements, unless the context indicates otherwise.

OVERVIEW

[0024] A fusion system uses optical control to manipulate the quantum state of a fluid fuel (e.g., water) such that spontaneous fusion occurs via tunnelling with sufficient probability to generate a meaningful number of fusion reactions that generate more energy than is used to configure and maintain the system when the non-colinear four wave mixing scheme is achieved efficiently. Generally, a first laser pulse causes fuel molecules (e.g., water molecules) to transition to an excited state (e.g., the electronic state) and a second pulse manipulates the phase of the

excited molecules to encourage fusion via tunnelling through the Coulomb barrier. The described fusion system may operate at low (e.g., ambient or below ambient) temperatures. 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. EXAMPLE FUSION SYSTEM

[0025] FIG. 1 illustrates one embodiment of a fusion system. In the embodiment shown, the fusion system includes a laser source 110 and a reactor 150. Various optical components are used to split and modify the beam generated by the laser source 110 and direct the resulting beams into the reactor 150. 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 150 is shown, a single laser source 110 may exhibit multi-megahertz repetition rates and can be connected to more than one reactor 150 via a time-division demultiplexer.

[0026] The laser source 110 generates an optical beam having a fundamental frequency. In one embodiment, the laser source 110 includes a Kerr-lens mode- locked oscillator, pumped with a Coherent V5 continuous wave laser, and a multi- pass ring cavity amplifier, pumped with a Photonics DM-20 Q-s witched 170 ns Nd:YLF laser. The output of the amplifier may be a 1.5 mJ pulse with a 1 kHz repetition rate, 30 fs pulse duration, and a central wavelength of 780 nm. The pulses may be spectrally broadened in a hollow-core fiber and the blue side of the spectrum (e.g., 605nm) may be selected. In other embodiments, laser sources of other types with different fundamental frequencies may be used.

[0027] An optical assembly modifies the beam generated by the laser source 110 and directs the modified beam into the reactor 150. In the embodiment shown in FIG. 1, the optical assembly includes a beam-splitter 112 that splits the input beam into two portions. The first portion is used for generating an ultraviolet (UV) beam and the second portion is used for generating a vacuum ultraviolet (VUV) beam.

[0028] The first portion of the fundamental frequency beam is directed to a first barium borate (BBO) crystal 122. In one embodiment, the BBO crystal 122 is 250 μm thick and cut for second harmonic generation (e.g., θ = 40.3°, Φ = 0°, Type I SHG). The resulting intermediate second harmonic beam may pass through a calcite plate 124 (e.g., a 1 mm thick calcite crystal, θ = 41°, Φ = 0°) to compensate for group velocity dispersion (GVD) and a half-wave plate 126 to make the fundamental and second harmonic the same polarization.

[0029] The fundamental and second harmonic beams may be used to generate one or more additional beams of different harmonics. In one embodiment, the fundamental and second harmonic beams are combined in a second 100 μm thick BBO crystal 128 cut for third harmonic generation ( θ = 76°, Φ = 0°) in order to generate light at 201 nm via sum frequency generation (SFG). After the SFG BBO crystal 128, high reflectivity dielectric mirrors for the third harmonic may be used to separate out the third harmonic from the fundamental and the second harmonic.

[0030] A second beam-splitter 132 may be used to split the third-harmonic beam into two portions. The second beam-splitter 132 may be an uncoated 1 mm thick CaF₂ window at 45° to the beam. The first portion of the third-harmonic beam is directed to a first optical input of the reactor 150 while the second portion is directed to a second optical input of the reactor via a UV pulse shaper 160.

[0031] The first portion of the third-harmonic beam is directed to a lens 142 (e.g., a 30 cm CaF2 lens) that focuses the UV light of the third-harmonic beam and the second portion of the beam having the fundamental frequency into a noble gas cell (e.g., within the reactor 150) to generate a fifth-harmonic VUV beam. A telescope or other optical system may be used to correct for the chromatic aberrations introduced by the lens 142. In one embodiment, generation of the fifth harmonic (e.g., 121nm) is achieved by non-collinear four- wave mixing in a noble gas (e.g., argon) that satisfies the following phase matching condition:

The pressure of the noble gas cell and the phase matching angles of the pulses may be calibrated experimentally. [0032] Alternatively, the fifth harmonic may be generated by doubling the frequency of a blue tuned titanium sapphire laser (i.e., two photons at 729 nm to produce one at 365nm), and then make use of third-harmonic generation of the frequency doubled light in the noble gas to produce 121 nm. For example, a titanium sapphire laser may be put through a stretched hollow core fiber to broaden and blue shift the spectrum to be centered around 730 nm. This light may be doubled to make 365 nm, and then tripled in a Kr/Ar gas mixture.

[0033] The UV pulse shaper 160 manipulates the second portion of the third- harmonic beam into control pulses that generate light-induced conical intersections in the fuel which develop quantum interference patterns to realize unitary phasekick control of tunnelling. In one embodiment, a radio frequency (RF) signal is sent to an acousto-optic modulator to generate a sound wave from which the optical pulses are diffracted. This enables modifying the phase and amplitude of the different optical frequencies to shape the optical (UV) pulse. The RF signal can be modulated to shape the optical pulses to obtain a desired pulse shape.

[0034] Unitary phase-kick control of quantum tunneling enables pulse energies to be used that can be orders of magnitude lower than those used in conventional IC fusion approaches (which rely on stimulating thermal motion to provide sufficient energy to overcome the Coulomb barrier and induce fusion) and still result in a comparable rate of fusion reactions. For example, low intensity VUV pulses (10¹¹ W /cm²) and moderate intensity UV pulses (10¹² W/cm²) are used in embodiments, which are at least nine orders of magnitude lower than pulse intensities required by IC fusion approaches to reach thermonuclear ignition of the fusion fuel.

[0035] Although a specific embodiment using specific quantum control involving pi phase kicks is described, it should be appreciated that a wide range of quantum control is possible and pattern recognition or machine-learning models may be used to identify quantum control protocols that result in high fusion output. Note that while the system as a whole may operate at low temperatures (e.g., between 0 and 100 degrees Celsius), individual molecules under control have high energy.

[0036] FIG. 2 illustrates one embodiment of the reactor 150. In the embodiment shown, the reactor 150 includes a noble gas cell 210 and a reaction chamber 220. The noble gas cell 210 holds a noble gas or mixture of noble gasses at a predetermined pressure to facilitate generation of the fifth-harmonic beam. The reaction chamber is where the pulsed optical beams interact with the fuel to facilitate fusion. In other embodiments, the reactor 150 may be configured differently.

[0037] The noble gas cell 210 is supplied noble gas via a gas inlet 214 and maintained at a predetermined pressure. In embodiments, a few hundred Torr, a pressure between approximately 0.1 and 1 atmosphere (76 to 760 Torr) is used. In one embodiment, the third-harmonic and fundamental frequency beams enter the noble gas cell 210 through an optical input 212 (e.g., a 2mm thick CaF₂ window). The beams interact via non-collinear four-wave mixing to generate a fifth-harmonic beam. Insert 218 illustrates an example phase matching condition for generation of the fifth-harmonic beam. The fifth-harmonic beam passes through an optical output 216 (e.g., a 500 μm thick CaF₂ window), which is a second optical input into the reaction chamber 220.

[0038] The reaction chamber 220 includes a molecular nozzle 222 configured to generate a molecular beam or liquid jet of the fuel. In FIG.2, the molecular beam is directed to be coming directly out of the page. The reaction chamber may be maintained at a low pressure (e.g., 10^-7 Torr). The fifth-harmonic and third-harmonic pulses interact with fuel molecules in the molecular beam to facilitate fusion via quantum control. In one embodiment, the VUV pulse first passes under the repeller plates 223 of a velocity map imaging (VMI) spectrometer. The VUV pulse is then reflected by a dichroic mirror 240 (e.g., with a radius curvature R = 268 mm). The mirror may have a high reflectivity coating of > 90% at 0° for 121 nm light and < 5% reflectivity for 201 nm and 605 nm. This enables the residual UV and visible radiation left over from VUV generation to be separated from the VUV.

[0039] The reflected VUV-pulse is focused under the VMI spectrometer repeller plates 223. The UV reserved for the second pulse is sent through the dichroic mirror 240 and also focused under the VMI spectrometer repeller plates 223. The VUV pulse reflected from the dichroic mirror 223 inside the reaction chamber 220 is steered under the hole in the repeller plates.

[0040] In one embodiment, this is done using a movable mirror mount. An example movable mirror mount is shown in the inset 270 of the figure. The illustrated movable mirror mount includes a KF40 blank with a hole drilled through the center and a o-ring groove set around the hole as a window holder. The KF40 window holder is connected to a KF40 bellow. Around the neck of the bellow a collar there are three holes in the side where the ball tip head of a high precision 1/4"-80 Fine Hex Adjuster 20 can sit. An aluminum (or other suitable material) frame with three slots is positioned to lock 1/4"-80 Locking Bushings with Nuts in place. This aluminum frame may be bolted in place independent of the reaction chamber 220. The 1/4"-80 Fine Hex Adjusters are threaded through the 1/4"-80 Locking Bushings. When the reaction chamber 220 comes under vacuum, the bellow contracts and the 1/4"-80 Fine Hex Adjuster ball tip heads come into contact with the holes in the collar. This acts like a Gimbal mount for the dichroic mirror 240 and enables steering of the VUV beam.

[0041] The reaction chamber also includes one or more energy extractors 230. The energy extractors 230 interact with fusion products (e.g., fast neutrons) to extract energy. For example, the fusion products may be used to heat water to drive a turbine (outside of the reaction chamber) or a scintillator/semiconductor system may be used to convert the fusion products into visible light and then electrical energy, etc. It should be appreciated that any suitable energy extraction methods may be used to capture the energy released by fusion reactions. Fusion products are released isotropically around the solid angle surrounding the interaction region (i.e., uniformly about 4π steradians). Thus, the energy extractors 230 are typically configured to maximize the surface area of the energy extractors around this solid angle within the confines imposed by the other elements of the system.

[0042] FIG. 3 illustrates an example process for calibrating the fusion system using a VMI spectrometer. The VMI spectrometer employs an electrostatic lens and a microchannel-plate (MCP) and phosphor based position-sensitive detector. The VMI spectrometer is illustrated together with a fast time-stamping camera. The electrostatic lens may include a standard repeller-extractor-ground electrode lens sitting inside a μ-metal sheet cylinder for magnetic shielding. The first (VUV) and second (UV) pulse beams propagate parallel through the repeller plates 223 perpendicular to the molecular nozzle 222. Above the VMI plates 223 is a time-of- flight (TOF) tube 226 of known length (e.g., 20cm) and at the end of the tube, there is a charged particle position-sensitive 2D detector. The fluorescence light from the phosphor is collected by the camera.

[0043] In one embodiment, both the pump and probe pulses are linearly polarized with the polarization direction perpendicular to the TOF direction such that there is symmetry about the laser polarization allowing for an Abel inverse transformation the data. The data collected by the camera provides spatially resolved molecular geometry data, which may be used to determine how to shape the laser pulses using pattern recognition search algorithms to optimize the reaction. The calibration process determines what pulse shape/sequences are optimal (or at least close to optimal) for driving fusion. In embodiments, "closed loop learning control" is used. A measurement of the yield is performed for a collection of random pulse shapes/sequences. A collection of the best pulse shapes is used to start a search for an optimal pulse shape/sequence using a pattern recognition algorithm. Given that one expects a very low fusion yield for a random initial pulse, the system may be initialized with some pulse shapes that are good first guesses given prior knowledge/experience. Any suitable observable indicative of the amount of fusion occurring may be used to help guide the system close to the ultimate goal - e.g. high energy protons that come from bringing H atoms close together which are recorded in the VMI spectrometer signal.

QUANTUM CONTROL EXAMPLES

[0044] FIGS. 4 through 10 and the corresponding description explain 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.

[0045] FIG. 4 illustrates energy as a function of separation of particles.

Specifically, FIG. 4 illustrates how particles can transition via tunnelling from a molecular bound state to the continuum of product translational states. In a system in which the protons are bound in the electronic structure of a small molecule, they can decay into a manifold of continuum states (e.g. neutrons, helium ions) generated by reactive collisions. While this process is unlikely to be observed without any perturbation, unitary phase-kick control can drastically accelerate tunneling rates relative to spontaneous behavior. With appropriate optical control, fusion can occur via tunnelling through the Coulomb barrier without the need for conventional, brute force thermonuclear approaches.

[0046] A molecular bound state initially prepared in state decays by tunneling

through the Coulomb barrier into the manifold of continuum states generated by

reactive collisions. The Hamiltonian for this reaction is:

where and

are the stationary eigenvalues. When are not equal to 0, the

state is non-stationary. In the absence of perturbations, the time-dependent wavefunction

satisfies:

[0047] By solving the time-dependent Schrodinger equation using initial conditions cs(0) = 1 and ck(0) = 0, the equations of motion for the expansion coefficients may be recovered:

Integrating yields the standard expression for the spontaneous tunneling probability by population decay of state I s) as a consequence of coupling to the manifold of continuum states Ik):

and is valid up to second order in perturbation theory. It should be emphasized that this is calculating a perturbation expansion for the tunneling probability in powers of the coupling between the bound state and the manif old of continuum states

Since this coupling is weak, the problem falls withing the radius of convergence for the perturbation expansion.

[0048] FIG. 5 demonstrates the acquisition of a geometric phase

by the eigenstate

upon encirclement of a light-induced conical intersection. The base manifold, M, is the projective Hilbert space of nuclear configurations belonging to a given electronic state. The typical fiber is the U(1) Lie group, the set of phase factors. Eigenstates of the nuclear wavefunction

exist in the bundle space and the dynamical evolution of an eigenstate is represented by a path E in the bundle space. Consider a closed circuit C in the base space of the fiber bundle. The Berry connection 1-form provides a unique way to lift this path to the path E in the bundle, which begins and ends on the same fiber. Since the fiber is a group, there will exist an element of the fiber that maps the starting point of the bundle path to the ending point. This element is the holonomy. In the case of a U(1) fiber, the holonomy corresponding to the path C may be written as which is the difference in

phase between the initial and final eigenstates (i.e., the geometric phase). For light- induced conical intersections, the holonomy is exactly equal to pi.

[0049] Because the actual acquisition of the phase is instantaneous upon completion of a circuit in configuration space enclosing the light-induced conical intersection, the encirclement may be represented by an operator acting on the

wavefunction

which changes the sign of the projection of the time-evolved wavefunction along

leaving unaffected the projection of along the manifold of states in the

continuum. [0050] To calculate an expression for the tunneling probability at time

as a function of the time interval Δt between repeated actions of the operator

corresponding to repeated encirclements of a light-induced conical intersection in configuration space) we introduce stochastic variables

that take on the values ±1 with equal probability and correspond to the operator acting on the system at time

The survival probability of the bound states

evolving under the influence of the operator is then given by:

is neglected since it involves terms of

To analyze the effect of averaging over all sequences of pi phase kicks, we

consider independent random variables with for which

Therefore, and the average survival probability at time

Integrating yields the average tunneling probability under control:

The above expression demonstrates how the parameters of the control field can be used to optimize quantum-controlled fusion by suitably modifying properties of the light-induced conical intersection such that the time interval At between encirclements maximizes the tunneling rate relative to spontaneous behavior.

[0051] In one embodiment, quantum control generates a light-induced conical intersection whose encirclement changes the fixed-phase relationship between eigenstates of the nuclear wavefunction via acquisition of a geometric phase, which is the holonomy (i.e., the desired unitary transformation of a pi phase-kick).

Repeated encirclements elicit-reactive quantum interferences.

[0052] FIG. 6 illustrates how the electronic structure of water is suitable for quantum controlled fusion. FIG. 6 shows three adiabatic electronic surfaces describing the photodissociation reaction coordinate for water isotopologues. In one embodiment, the unitary quantum dynamics of the nuclear wavefunction are steered along this reaction coordinate to elicit a quantum interference pattern that establishes probability amplitude in classically forbidden regions of configuration space. The optical pulses described previously place the nuclear wavefunction of water into a highly oscillatory time-evolved state where tunneling through the Coulomb barrier is accelerated relative to spontaneous behavior, resulting in fusion of hydrogen nuclei.

[0053] Specifically, in embodiments of the described fusion system, photodissociation dynamics are initiated by a first optical control pulse in the VUV range that results in vertical excitation of the water molecule to the electronic

state. The ensuing quantum dynamics of the nuclear wavefunction populate the

electronic state, from which further dynamical evolution results in near-total closure of the bond angle between bound hydrogens at a natural point of conical intersection between the electronic states. This conical intersection arises because a

linear approach of H to OH on the repulsive potential curve from can

cross an attractive potential curve from whereas there is an avoided

crossing of these curves in the lower symmetry of a bent geometry.

[0054] As compared to prior art fusion techniques in which confinement of atomic nuclei must be actively maintained by external potentials (e.g. in MC fusion approaches), in the described fusion reactor, confinement is a passive consequence of the electronic structure of water, which provides the screening to stabilize the nuclear wavefunction at enlarged configuration space densities. Depending on which hydrogenic isotopologue of water is used, fusion can occur with: H-H, H-D, H-T, D- D, D-T, or T-T.

[0055] FIG. 7 illustrates a light-induced conical intersection, which can be generated by a monochromatic field. The properties of the second pulse in the bichromatic control protocol determine properties of the light-induced conical intersection. For example, the frequency of the field determines its position while the intensity determines the steepness of the cones. Thus, the light-induced conical intersection can be manipulated to create a desired field-dressed electronic profile for increasing the probability to tunnelling-driven fusion occurring.

[0056] FIG. 8 illustrates room temperature cross-sections for water with VUV light. Two factors that limit the yield of the fusion process are the cross section for light-matter interaction and the tunnelling probability under unitary phase-kick control. As illustrated in FIG. 8, the cross section has a peak corresponding to the electronic state at 121nm. The cross sections for light-matter interaction

shown are orders of magnitude greater than the best possible thermonuclear cross sections achievable using conventional fusion techniques. For example, the water- VUV cross section at 121nm is nine orders of magnitude greater than the best possible D-D thermonuclear cross section. In numerical simulations of unitary phase-kick control, tunneling through a MeV Coulomb barrier can be achieved with greater than 50% probability using repeated pi phase-kicks to the nuclear wavefunction. See, e.g., Saha, R., Markmann, A., Batista, V. S. (2012). Tunneling through Coulombic barriers: quantum control of nuclear fusion. Molecular Physics, 110(9-10), 995-999; Saha, R., Batista, V. S. (2011). Tunneling under coherent control by sequences of unitary pulses. The Journal of Physical Chemistry B, 115(18), 5234-5242; and Rego, L. G., Abuabara, S. G., Batista, V. S. (2007). Multiple unitary-pulses for coherent-control of tunnelling and decoherence. Journal of Modem Optics, 54(16- 17), 2617-2627, all of which are incorporated by reference.

[0057] The energy available in the fusion of two hydrogen nuclei is on the order of 1 MeV. If one starts with laser pulses having an energy of 1 mJ, this requires on the order of 10¹⁰ fusion events per laser pulse. In the gas phase, the number density is approximately 10¹⁴ molecules per cc. With a laser focus of 100 microns and a VUV and UV pulse propagation path length of 1cm in the gas phase, the total focal volume is 10⁴ cc, so the total number of molecules in the focal volume is about 10¹⁰ molecules for the gas phase molecular beam. The gas phase is thus particularly useful for calibration and diagnostic measurements which require low number densities for coincidence statistics in the VMI spectrometer.

[0058] In the liquid phase (e.g. a liquid jet), the number density of molecules is nine orders of magnitude larger, and so the number of molecules in the optical path no longer limits the ability to extract energy from the sample. Rather, it is the number of UV and VUV photons available. With a VUV conversion efficiency of 10^-3, one can produce on the order of 10¹³ photons per pulse, and if all of these photons are absorbed, a fusion yield of 10^-3 achieves net positive energy production. If higher VUV conversion efficiency is achieved, then lower fusion yields are required to break even or achieve net positive energy production. [0059] The unitary phase kick control is observed so long as quantum coherences in the nuclear wavefunction survive for longer than the duration of reactive scattering events. The rotational-vibrational decoherence timescale of hydrogen in liquid water due to hydrogen bonding is ~100-200fs as measured by coherent anti- Stokes Raman spectroscopy. Considering the timescales involved and the duration of control pulses, unitary phase-kick control of quantum tunneling can be observed even in liquid water.

[0060] FIG. 9 illustrates a stochastic model of pi phase kicks leading to acceleration of quantum tunneling into the continuum and, when averaging over all possible realizations, the stochastic model recovers the decay rate analyzed in the context of the quantum anti-Zeno effect. This provides a catalytic mechanism analysis for the acceleration of fusion reaction rates relative to spontaneous or thermal behavior.

[0061] FIG. 10 illustrates an exemplary quantum interference pattern elicited by conical intersections on the natural electronic structure when water is excited by the first VUV pulse in the bichromatic control protocol at 121nm. The shaded lobes are positive quantum amplitude regions and the unshaded lobes are negative quantum amplitude regions. The system modifies these natural interference patterns with a light-induced conical intersection, generated by the second UV pulse, to accelerate through the Coulomb barrier between the hydrogen nuclei. The lobes are illustrating the probability amplitude of locating the second hydrogen atom in water. The hatched region on the surface is the Frank-Condon region for vertical excitation

from the electronic surface recovering the familiar equilibrium geometry of

water.

[0062] The electronic structure of water provides the screening to stabilize the nuclear wavefunction at configuration space densities which are enlarged as compared to prior art. The electronic structure additionally confines the nuclear motion to a plane defined by the positions of the three atoms (i.e., H, H, O). To observe unitary phase-kick control of tunneling through the Coulombic barrier between the two hydrogen nuclei bound in water, the system changes the fixed- phase relationship between eigenstates of the nuclear wavefunction to elicit reactive quantum interference patterns. This is achieved by the holonomy of the base manifold M, the projective Hilbert space of nuclear configurations belonging to a given electronic state, with a light-induced conical intersection. The base manifold is endowed with holonomy by the second pulse in the bichromatic control protocol, which causes the non-adiabatic coupling terms of the nuclear Schrodinger equation not only to become infinitely large at the point of degeneracy but also dress as poles. Being poles, the non-adiabatic coupling terms become the source of numerous phenomena that are considered topological effects.

[0063] In water, there are natural conical intersections between the electronic

surface and the

electronic surface which elicit natural quantum interference patterns when water is irradiated at 121nm (the Lyman-ci wavelength). The interference patterns illustrated in Figure 10 do not result in a viable amount of fusion although it can be seen there is some probability amplitude at extremely short distances between the two protons (about 50pm) on the

electronic surface. This occurs because one of the natural conical intersections is symmetry-required at a linear O-H-H geometry, so the two protons will approach each other as the bond angle closes on the electronic surface during VUV photodissociation. The

technology renormalizes the electronic structure of water, to control the position of light-induced conical intersections whose field-dressed positions and geometries in the Floquet picture of quantum mechanics are determined by the position of these natural conical intersections. Therefore the technology modifies the associated natural interference patterns to result in fusion, with a second optical control pulse. The second control pulse applied after irradiating water at 121nm generates light- induced conical intersections which develop interference patterns sufficient to realize unitary phase-kick control of tunneling in water. Notably, this approach can utilize pulse energies which are at least nine orders of magnitude lower than those utilized by prior art, which relies on the classical ergodicity of thermal motion to achieve reactive collisions. The described approach is further amenable to optical control with regards to timing between the two pulses, wavelengths, the temporal pulse envelopes, etc.

[0064] One way to optimize the control protocol is to use the VMI spectrometer which provides direct geometry data (i.e., how close are the protons in the control field) and is furthermore a statistically robust observable with which to run an evolutionary pulse shaping experiment in the gas phase. "Closed loop learning control" is used. In the closed loop learning, one performs a measurement of the yield for a collection of random pulse shapes/sequences. Then a collection of the best pulse shapes is used to start a pattern recognition search algorithm based search for an optimal pulse shape/sequence.

ADDITIONAL CONSIDERATIONS

[0065] As used herein, any reference to "one embodiment" or "an embodiment" means that a particular element, feature, 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. [0066] 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."

[0067] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "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 to 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).

[0068] 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

CLAIMS What is claimed is:

1. A fusion reaction system comprising: a laser source that generates an input beam; an optical assembly that generates, using the input beam, a first pulsed beam and a second pulsed beam; a reaction chamber having a first optical input and a second optical input, the rection chamber configured to contain a fluid fuel, wherein the first pulsed beam enters the reaction chamber through the first optical input and excites particles of the fluid fuel into an excited state, and the second pulsed beam induces phase shifts to the particle in the excited state such that a fusion probability exceeds a viability threshold; and an energy extractor that extracts energy generated by fusion reactions from the reaction chamber.

2. The fusion reaction system of claim 1, wherein the input beam has a wavelength of approximately 605nm.

3. The fusion reaction system of claim 1, wherein the second pulsed beam is a third harmonic of the input beam.

4. The fusion reaction system of claim 3, further comprising: a first BBO crystal that generates an intermediate beam that from the input beam that is a second harmonic of the input beam; and a second BBO crystal that generates a second intermediate beam that is a third- harmonic of the input beam via sum-frequency generation using the input beam and the intermediate beam, wherein the second pulsed beam is at least a portion of the second intermediate beam.

5. The fusion reaction system of claim 4, wherein the first pulsed beam is a fifth harmonic of the input beam.

6. The fusion reaction system of claim 5, further comprising: a second beam splitter that splits the second intermediate beam into the second pulsed beam and a third intermediate beam; a pulse shaper that modifies at least one of a phase or an amplitude of frequency components of the third intermediate beam; and a noble gas cell in which the first pulsed beam is generated via non-collinear four- wave mixing of the third intermediate beam and a portion of the input beam.

7. The fusion reaction system of claim 6, wherein the noble gas cell includes at least one of Argon or Krypton gas at a predetermined pressure.

8. The fusion reaction system of claim 6, wherein the pulse shaper comprises: a grating; a curved mirror, wherein the grating and the curved mirror are configured to spatially separate the frequency components of the intermediate beam; and an acousto-optic modulator configured modify the at least one of the phase or the amplitude of the frequency components.

9. The fusion reaction system of claim 8, wherein the acousto-optic modulator is further configured to modify the at least one of the phase or the amplitude of the frequency components based on a pattern recognition model.

10. The fusion reaction system of claim 1, wherein the fuel is provided in a molecular beam generated by a nozzle.

11. The fusion reaction system of claim 1 , wherein the fuel is a hy drogenic isotopologue of water.

12. The fusion reaction system of claim 11, wherein the first pulsed beam excites water molecules into the electronic state.

13. The fusion reaction system of claim 12, wherein the phase shifts introduced by the second pulsed beam include a set of pi phase-shift kicks.

14. The fusion reaction system of claim 13, wherein the phase shift-kicks increase a probability of a fusion event occurring due to a particle quantum tunneling through the Coulomb barrier into a continuum of product translational states.

15. The fusion reaction system of claim 1, wherein fusion occurs while the reaction chamber is at a temperature between approximately zero and approximately one hundred degree Celcius.

16. The fusion reaction system of claim 1, wherein the energy extractor generates heat from fusion products and provides the heat to drive a turbine.

17. The fusion reaction system of claim 1, wherein the energy extractor includes a scintillator that converts fusion products to visible light and a semi-conductor that converts the visible light into an electrical current.

18. The fusion reaction system of claim 1, wherein the input beam comprises femtosecond pulses.

19. The fusion reaction system of claim 1, wherein the fluid fuel comprises a beam of gas-phase water molecules or a liquid jet of water molecules.

20. The fusion reaction system of claim 1, wherein the fluid fuel comprises a beam of gas-phase water molecules in a diagnostic/ calibration mode and a liquid jet of water molecules in a power-generation mode.