Inertial Confinement Fusion Reactor Research Articles

The challenges of nuclear fusion reactor

Energy shortage is one of nonnegligible problems nowadays. Even since the twenty centuries, the achievement of fission reactor has proved that nuclear energy is a powerful source. However, fission reaction could cause radiation hazard if operation error happens. Nuclear fusion can provide more clean energy. This paper discusses nuclear fusion and two typical models of fusion reactor, inertial confinement fusion reactor and tokamak, and their properties. Fusion reactors use deuterium and tritium to fuse heavier nucleus and release energy. With -distribution, deuterium-tritium fusion reactivity can be boosted at relatively low temperature. Furthermore, fusion reactor has initial success. The more energy can be created than energy used to ignition. To solve nuclear fuel problem, continue ignition progress problem, possibly achieving controllable fusion reaction. The improvements which this paper mentioned perhaps allow to extend the application context of fusion reactor.

Refractive index measurement of hydrogen isotopologue mixture and applicability for homogeneity of hydrogen solid at cryogenic temperature in fusion fuel system

Deuterium (D)-Tritium (T) nuclear fusion reaction has potential as an energy source in the future. In both magnetic confinement and inertial confinement fusion reactors, solid D–T will generally be supplied as fusion fuel. The efficiency of the nuclear fusion reaction depends on the quality of solid D–T fuel, which is related to the composition, homogeneity, helium-3 (3He) content, and so on. However, there is no technique for in-situ examination of solid D–T fuel. In this study, we consider a simple and precise method for the characterization of solid hydrogen isotopologues at cryogenic temperature using refractive index measurement, and evaluate the distribution of hydrogen isotopologue composition and homogeneity. To evaluate without the effect of tritium decay, the homogeneity of the hydrogen (H2)-deuterium (D2) mixture is measured at first. By the in-situ refractive index measurement at cryogenic temperature, the homogeneity of solid H2–D2 mixture is roughly quantified. The phase diagram of the H2–D2 mixture shows a solid solution type. D2-rich crystal first appears from the liquid phase as a primary crystal. The composition of D2 in liquid phase ias homogeneous, whereas it reduces by obeying the liquidus line in the phase diagram with the crystallization. On the other hand, the composition of the H2–D2 mixture in solid phase is inhomogeneous because the mobility of H2 and D2 in solid phase was too slow to be homogeneous and solid. The compositions of H2–D2 mixture in liquid and solid phases could be evaluated by the in-situ refractive index measurement in time. Consequently, the refractive index measurement shows great potential as an inspection method of solid D–T fuel in fusion reactors.

Reduction in inertial confinement fusion ignition energy of 3He-3He plasma by laser-accelerated deuterons

The supply of the required energy to achieve the fuel ignition is one of great concern in a fusion reactor. High amount of energy is needed for the ignition of 3He-3He fuel in a fusion reactor which is due to the losses of radiation and the requirement for high-temperature electrons and ions. The fast ignition (FI) approach causes a decrease in the laser power required to reach a large energy gain in an inertial confinement fusion (ICF) reactor. Ions have the benefit of having classical interaction through Coulomb dispersion with the background plasma. In this method, it is suggested to use deuteron beam for decreasing the ignition energy of the 3He-3He fuel. The deuteron particles would fuse with ions into fuel (helium-3) and produce additional energy. This excess energy has a considerable role in increasing energy gain in an 3He-3He fusion reactor. In this paper, the value of the energy efficiency coefficient (Y-value) and the total deposited energy are computed at different deuteron beam energy and electron temperature. The results show that Y-value is independent of helium-3 numerical density in the 3He-3He plasma and increases slowly with an increase in ion temperature. This fact is substantial at little deuteron energy and high electron temperature.

Instability of a Radially Moving Cylindrical Surface: A Viscous Potential Flow Approach

Abstract The effect of viscosity on the unstable interface of the cylindrical jet is analyzed through viscous potential flow approach. The jet is moving radially and jet interface is experiencing Rayleigh–Taylor type instability. Previous studies have completely ignored the viscosity effect while considering the instability of a radially moving cylindrical jet. The fluids inside and outside jet are incompressible as well as viscous. The theoretical analysis provides us a second-order ordinary differential equation to establish the instability/stability criterion. The radial velocity and acceleration both have significant impact on the stability of the jet. We found that as viscosity enters to the analysis, perturbations grow rapidly. In addition, the acquired stability criterion is applied to the cylindrical jets in HYLIFE-II which is basically an inertial confinement fusion reactor.

Erratum: “Equation-of-state, critical constants, and thermodynamic properties of lithium at high energy density” [Phys. Plasmas 26, 122702 (2019)

High-density lithium plasmas are expected to be generated in the Inertial Confinement Fusion (ICF) reactor chamber due to energy deposition of the prompt X-rays and ion debris in the first wall. These dense plasmas are encountered in many other applications as well. The design and optimization of such lithium-based applications requires information about the thermodynamic properties of Li fluid over a wide range of parameters including the high-energy-density regime. A model that takes into account all essential features of strongly-coupled plasmas of metal vapors is developed and used to predict the equation-of-state (EOS), critical constants, thermodynamic functions, and principal shock Hugoniot of hot dense lithium fluid. Predictions and computational results from the present model are analyzed and presented and are available in electronic form suitable for use to interested researchers and scientists.

Fuel pellet injection into heavy-ion inertial fusion reactor

In inertial confinement fusion (ICF), the scientific issues include the generation and transport of driver energy, the pellet design, the uniform target implosion physics, the realistic nuclear fusion reactor design, etc. In this paper, we present a pellet injection into a power reactor in heavy ion inertial fusion. We employ a magnetic correction method to reduce the pellet alignment error in an ICF reactor chamber, including the gravity, the reactor gas drag force and the injection errors. We found that the magnetic correction device proposed in this paper is effective to construct a robust pellet injection system with a sufficiently small pellet alignment error. A fuel pellet would be covered by Pb and is cooled down by a liquid He. The cryo-pellet coated by Pb becomes a superconductor, when its temperature is below 7.2K. The magnetic field repels the superconductor due to the Meissner effect. We employ this effect to correct the fuel pellet injection velocity. The results of simulations demonstrate that the magnetic correction system is effective and robust to reduce the pellet alignment error.

Equation-of-state, critical constants, and thermodynamic properties of lithium at high energy density

High-density lithium plasmas are expected to be generated in the Inertial Confinement Fusion reactor chamber due to energy deposition of the prompt X-rays and ion debris in the first wall. These dense plasmas are encountered in many other applications as well. The design and optimization of such lithium-based applications require information about the thermodynamic properties of Li fluid over a wide range of parameters including the high-energy-density regime. A model that takes into account all essential features of strongly coupled plasmas of metal vapors is developed and used to predict the equation-of-state, critical constants, thermodynamic functions, and principal shock Hugoniot of hot dense lithium fluid. Predictions and computational results from the present model are analyzed and presented and are available in electronic form suitable for use to interested researchers and scientists.

Numerical simulation of flow instability in a circular tube under pulse heating condition

Energy systems based on inertial confinement fusion or fusion-fission hybrid reactor generate energy in the form of pulse heating, which may lead to new flow instability phenomenon in the cooling system. In order to make thermal hydraulic design of pulse heating energy system safe and reliable, it is necessary to deeply understand the oscillation characteristics of flow and heat transfer under the pulse heating condition. As for the first stage of this complicated research, the numerical simulation of coolant flow in a circular tube under pulse heating condition is executed in this paper. The oscillation characteristics of flow and heat transfer under different pulse heating conditions are discussed in detail, and the effect of heating power, pulse heating period and duty ratio are studied. Four flow development stages (stage A – stage D) are identified, and three kind of flow oscillation phenomenon are found according to the numerical results with increasing the pulse heating power. The analysis shows that oscillation is mainly caused by pulse heating itself or the combination of pulse heating and density wave oscillation (DWO). Increasing the pulse heating period is beneficial to decrease flow oscillation, and decreasing the duty ratio, the flow oscillation is more obvious. The flow development stage maps are also given in the plane of average power and inlet subcooled temperature. With the increase of period, the stage D appears more easily at lower average power. When the duty ratio decreases, the region of stage C in instability map becomes larger.

Cryogenic Hydrogen Fuel for Controlled Inertial Confinement Fusion (Cryogenic Target Factory Concept Based on FST-Layering Method)

A central element of a power plant based on inertial confinement fusion (ICF) is a target with cryogenic hydrogen fuel that should be delivered to the center of a reactor chamber with a high accuracy and repetition rate. Therefore, a cryogenic target factory (CTF) is an integral part of any ICF reactor. A promising way to solve this problem consists in the FST layering method developed at the Lebedev Physical Institute (LPI). This method (rapid fuel layering inside moving free-standing targets) is unique, having no analogs in the world. The further development of FST-layering technologies is implemented in the scope of the LPI program for the creation of a modular CTF and commercialization of the obtained results. In this report, we discuss our concept of CTF (CTF-LPI) that exhibits the following distinctive features: using a FST-layering technology for the elaboration of an in-line production of cryogenic targets, using an effect of quantum levitation of high-temperature superconductors (HTSCs) in magnetic field for noncontacting manipulation, transport, and positioning of the free-standing cryogenic targets, as well as in using a Fourier holography technique for an on-line characterization and tracking of the targets flying into the reactor chamber. The results of original experimental and theoretical investigations performed at LPI indicate that the existing and developing target fabrication capabilities and technologies can be applied to ICF target production. The unique scientific, engineering, and technological base developed in Russia at LPI allows one to make a CTFLPI prototype for mass production of targets and delivery thereof at the required velocity into the ICF reactor chamber.

Achievement of Laser Fusion with High Energy Efficiency Using a Mixture of D and T Ions

A mixture of deuterium (D) and tritium (T) is the most likely fuel for laser-driven inertial confinement fusion (ICF) reactors and hence DD and DT are the fusion reactions that will fire these reactors in the future. Neutrons produced from the two reactions will escape from the burning plasma, in the reactor core, and they are the only products possible to be measured directly. DT/DD neutron ratio is crucial for evaluation of T/D fuel ratio, burn control, tritium cycle and alpha particle self-heating power. To measure this ratio experimentally, the neutron spectra of DD and DT reactions have to be measured separately and simultaneously under high neutron counting with sufficient statistics (typically within 10% error) in a very short time and these issues are mutually contradicted. That is why it is not plausible to measure this high priority ratio for reactor performance accurately. Precise calculations of the DT/DD neutron ratio are needed. Here, we introduce such calculations using a three dimensional (3-D) Monte Carlo code at energies up to 40 MeV (the predicted maximum ion acceleration energy with the available laser systems). In addition, the fusion power ratio of DD and DT reactions is calculated for the same energy range. The study indicates that for a mixture of 50% deuterium and 50% triton, with taking into account the reactions D(d,n)3He and T(d,n)4He, the optimum energy value for achieving the most efficient laser-driven ICF is 0.08 MeV.

Planar geometry inertial electrostatic confinement fusion device

In the classic gridded inertial electrostatic confinement (IEC) fusion reactor, ion bombardment of the grid leads to heating, thermionic electron emission, significant power loss, and ultimately melting of the grid. Gridless IEC devices have sought to overcome these limitations. Klein reported a gridless device in which ions are circulated as a linear beam in an electrostatic analogue of an optical resonator. To overcome limits of stored ions due to space charge effects at the turning regions, the device employed multiple overlapping traps. The work reported here seeks to further increase the turning region space in a gridless trap by employing a planar geometry. Ion trapping in the planar device was examined by simulating trajectories of 2H+ ions with SIMION 8.1 software. Simulations were carried out using multiple potentials as in Klein's device and for a single potential trap as a planar analogue of the anharmonic ion trap. Scattering by background gas was simulated using a hard sphere collision model, and the results suggested the device will require operation at low pressure with a separate ion source.

Low-energy d+d fusion via the Trojan Horse Method

The 2H(d,p)3H and 2H(d,n)3He reactions have been recently investigated from Edd=1.5 MeV down to 2 keV, by means of the Trojan Horse Method (THM) applied to the Quasi Free 3He+d interaction at 18 MeV [1]. The knowledge of their fusion cross section at low energies is of interest for pure and applied physics. Both reactions belong to the network of processes to fuel the first inertial confinement fusion reactors in the range of kT= 1 to 30 keV. These energies overlap with the burning temperatures of deuterium in the Pre-main sequence of stellar evolution. They are key processes in the Standard Big Bang Nucleosynthesis (SBBN), in an energy region from 50 to 300 keV and experimental data at least up to 1 MeV are required for an accurate calculation of the reaction rate. Providing experimental data for both channels from a single experiment and over the entire energy range of interest is crucial for an accurate calculation of the reaction rates. This is what has been obtained from the present Trojan Horse (TH) investigation with new reaction rates which deviate by more than 20% from available direct data. This represents also the first pioneering experiment in quasi free regime where the charged spectator is detected.

Tritium Fuel System Assessment on Economics and CO2 Emissions in DT Fusion Reactors

The contribution of tritium fuel system construction and operation to the global COE and the life-cycle GHG emissions is analysed using PEC reactor system design code for both magnetic confinement fusion (MCF) and inertial confinement fusion (ICF) reactors. This contribution is less than a few percents in the present model, but the CO2 emissions from the ICF fuel system are rather higher than those from MCF, because of the DT pellet fabrication processes.

Environmental and Economical Assessment of Various Fusion Reactors by the Calculation of CO2 Emission Amounts

We compared the CO2 emissions of several fusion reactors. The magnetic confinement systems evaluated here are the tokamak reactor (TR), helical reactor (HR), and spherical tokamak reactor (ST). These models are calculated by the Physics-Engineering-Cost (PEC) code. The inertial confinement fusion reactor (IR) is also evaluated, assuming its driver energy and driver efficiency. In addition, different blanket modules and fuels are considered in the TR designs. To calculate life-cycle CO2 emission from fusion reactors defined by plasma parameters and radial build, we used a basic unit for CO2 weights (kt-CO2/t-material). Calculation results indicate that CO2 is emitted mainly in the construction stage of superconducting magnet systems for magnetic confinement fusion reactors. For the IR design, the driver system construction and pellet fabrication stages involve considerable CO2 emission. By comparing fusion reactors with other electric power generation systems in terms of CO2 emission, we confirmed that fusion reactors emit less CO2. Therefore, introducing a carbon tax has little effect on the economics of fusion reactors, and the cost of electricity (COE) from fusion reactors might be lower than that of oil-fired electric power plants when a carbon tax of around several hundred yen/t-CO2 is introduced.

High temperature surface effects of He + implantation in ICF fusion first wall materials

The first wall armor of the inertial confinement fusion reactor chambers must withstand high temperatures and significant radiation damage from target debris and neutrons. The resilience of multiple materials to one component of the target debris has been investigated using energetic (20–40 keV) helium ions generated in the inertial electrostatic confinement device at the University of Wisconsin. The materials studied include: single-crystalline, and polycrystalline tungsten, tungsten-coated tantalum-carbide ‘foams’, tungsten–rhenium alloy, silicon carbide, carbon–carbon velvet, and tungsten-coated carbon–carbon velvet. Steady-state irradiation temperatures ranged from 750 to 1250 °C with helium fluences between 5 × 10 17 and 1 × 10 20 He +/cm 2. The crystalline, rhenium alloyed, carbide foam, and powder metallurgical tungsten specimens each experienced extensive pore formation after He + irradiation. Flaking and pore formation occurred on silicon carbide samples. Individual fibers of carbon–carbon velvet specimens sustained erosion and corrugation, in addition to the roughening and rupturing of tungsten coatings after helium ion implantation.

Application of computational fluid dynamics (CFD) codes as design tools for inertial confinement fusion reactor

The engineering design of the new innovative fusion reactors constitutes a clear challenge for the need to overcome several new technological edges in every engineering aspect. The great amount of thermal energy delivered into any inertial fusion chamber and the large temperatures and thermal gradients that are envisaged, joined to the even more demanding aspects related to neutron activation, Tritium breeding and the characteristics that are imposed to the coolant that could be used for that purpose, converged into material selection in which liquid metal seems to be one of the most interesting options. The safety assessment of such Fusion reactors should be clearly provided to fulfill the requirements asked by the Regulatory Bodies in a near-term future, when licensing will be a must. Therefore the availability of well proven and validated engineering design tools is a must. In this context, CFD is one of the tools that are potentially needed for thermal-hydraulic design of such complex machines. The state-of-the-art of CFD technologies will be shown, in particular in relation with liquid metals.

Effects of High Temperature Pulsed Helium Implantation on Tungsten Surface Morphology

The durability and lifetime of thin tungsten or refractory metal coatings on the first walls of inertial and magnetic confinement fusion reactors is a key issue for the feasibility of such devices. Past studies at UW-Madison have indicated that tungsten, when subjected to He+ fluences in excess of 4 × 1017 He+/cm2, shows extensive pore formation at 800 °C.1,2 The current study attempts to produce more realistic results by simultaneously irradiating tungsten samples with helium and hydrogen species and by investigating the effects of pulsed helium ion irradiation on tungsten.

Implantation of He + in candidate fusion first wall materials

The effect of high temperature (700–1200 °C) implantation of helium in candidate fusion first wall materials was studied in the University of Wisconsin Inertial Electrostatic Confinement device. Powder metallurgy tungsten, single crystal tungsten, and a W–25% Re alloy were irradiated with 30–50 keV He + ions. Scanning electron microscopy was used to evaluate changes in surface morphology for various ion fluences at temperature ranges comparable to first wall temperatures. Helium fluences in excess of 1 × 10 18 He +/cm 2 produce extensive pore formation at 1150 °C. These changes will have an impact on the lifetime of thin tungsten coatings on the first walls and divertors of inertial and magnetic confinement fusion reactors.

Robust heavy-ion-beam illumination against a direct-drive-pellet displacement in inertial confinement fusion

Nonuniformity of heavy-ion-beam (HIB) illumination is one of key issues in the HIB inertial confinement fusion (ICF): implosion symmetry should be less than a few percent in order to compress a fuel sufficiently and release fusion energy effectively. In this paper a new HIB illumination scheme is presented in order to realize a robust illumination scheme against a displacement of a direct-driven fuel pellet in an ICF reactor. It is known that the HIB illumination nonuniformity is sensitive to a little pellet displacement from a reactor chamber center; a pellet displacement of only 50–100μm was tolerable in the conventional HIB illumination schemes. In this paper by three-dimensional computer simulations a new robust HIB illumination scheme was found, in which a 200–300μm displacement is allowed.

Power generation system using two models for an inertial confinement fusion reactor

In this study, the series cooling model and the parallel cooling model of inertial confinement fusion reactor were used as a heat source for driving the MHD/Gas Turbine combined power generation system. This reactor is designed with the first wall and the blanket, which are used to collect the products of fusion reactions (including X-ray, charged particles, and neutrons) and to convert the fusion energy into thermal energy. In the series cooling model, the coolant after being heated in the blanket is re-heated again in the first wall, therefore, > 2000 K working gas can be obtained. In the parallel cooling model, 1300-1700 K working gas was extracted from the blanket for driving the Gas Turbine cycle and high temperature 2000-2400 K working gas can be extracted from the first wall for driving the MHD cycle. The system using the series cooling model reached a highest plant efficiency of 58.34 per cent whereas the system using the parallel cooling model reached a highest plant efficiency of 57.49 per cent. It was found that the enthalpy extraction and the first wall output temperature both affected the fusion output power, therefore, the plant efficiency was greatly affected by these factors. With the increase of reactor output temperature, the plant efficiency increased, however, because of the temperature limitation of the Gas Turbine and blanket, an output temperature > 2400 K from reactor cannot be used.