Heavy Ion Inertial Fusion Research Articles

Effects of Radial Thermal Conduction and Radiation Transport During Fuel Pellet Implosion in Heavy-Ion Inertial Fusion

We investigated the effects of radial thermal conduction and radiation transport from a fuel pre-heating for during the implosion process. We proposed a target structure using a Pb pusher to prevent the pre-heating phenomenon. We compared the electron heat and radiation fluxes, optical thickness, radiation temperature of the fuel, and fuel compression ratio for the Al and Pb pushers. For the Pb pusher, the compression ratio of the fuel increased when pre-heating was prevented. The results indicated that a pusher with a high-Z and dense material could minimize pre-heating and achieve a high fuel compression ratio. This is because such a material can maintain higher opacity during the implosion process.

Code O-SUKI-N 3D: Upgraded direct-drive fuel target 3D implosion code in heavy ion inertial fusion

The Code O-SUKI-N 3D is an upgraded version of the 2D Code O-SUKI (Sato et al., 2019 [1]). Code O-SUKI-N 3D is an integrated 3-dimensional (3D) simulation program system for fuel implosion, ignition and burning of a direct-drive nuclear-fusion pellet in heavy ion beam (HIB) inertial confinement fusion (HIF). The Code O-SUKI-N 3D consists of the three programs of Lagrangian fluid implosion program, data conversion program, and Euler fluid implosion, ignition and burning program. The Code O-SUKI-N 3D can also couple with the HIB illumination and energy deposition program of OK3 (Ogoyski et al., 2010 [8]). The spherical target implosion 3D behavior is computed by the 3D Lagrangian fluid code until the time just before the void closure of the fuel implosion. After that, all the data by the Lagrangian implosion code are converted to the data for the 3D Eulerian code. In the 3D Euler code, the DT fuel compression at the stagnation, ignition and burning are computed. The Code O-SUKI-N 3D simulation system provides a capability to compute and to study the HIF target implosion dynamics. Program summaryProgram Title: O-SUKI-N 3DCPC Library link to program files:https://doi.org/10.17632/h8n474wvf5.2Licensing provisions: CC BY NC 3.0Programming language: C++Journal reference of previous version: Comput. Phys. Commun. 240, 83 (2019)Nature of problem: Nuclear fusion energy would be energy source for society. In this paper we focus on heavy ion beam (HIB) inertial confinement fusion (HIF). A spherical mm-radius deuterium (D) - tritium (T) fuel pellet is irradiated by HIBs to be compressed to about a thousand times of the solid density. The ion temperature of ∼5-10 KeV is required to ignite the DT fuel to release a sufficient fusion energy. The typical HIBs total input energy is several MJ, and the HIBs pulse length is about a few tens of ns. The O-SUKI-N 3D code system provides an integrated tool to simulate the HIF DT fuel pellet implosion, ignition and burning in 3 dimensions (3D). The O-SUKI-N 3D code system is an upgraded version of the Code O-SUKI (Sato et al., 2019 [1]) which is a 2D implosion simulation system in HIF. The DT fuel is compressed to the high density of about a thousand times of the solid density, and so the DT fuel spatial deformation may be serious at the DT fuel stagnation. Therefore, the O-SUKI and O-SUKI-N 3D systems employ a Lagrangian fluid code first to simulate the DT fuel implosion phase until just before the stagnation. Then all the simulation data from the Lagrangian code are converted to them for the Euler fluid code, in which the DT fuel ignition and burning are simulated.Solution method: In the two fluid codes (Lagrangian and Euler fluid codes) in the O-SUKI-N 3D system the three-temperature fluid model (Tahir et al., 1986 [10]) is employed to simulate the pellet dynamics in HIF.Additional comments including restrictions and unusual features: The Lagrange code is inherently weak against the spatial mesh deformation due to the implosion non-uniformity. When short-wavelength perturbations are imposed near the poles of the spherical target, the spatial meshes might crash and the computation run may stop.

Radioactive Isotope Induced by Beam Loss in Particle Accelerator for Heavy-Ion Inertial Fusion

Radioactive Isotope Induced by Beam Loss in Particle Accelerator for Heavy-Ion Inertial Fusion

A massive-ion beam driver for high-energy-density physics and future inertial fusion

Several heavy ion drivers for heavy ion inertial fusion have been proposed in the US and Europe, based on linear induction accelerator technology [1] and existing RF technology [2], respectively, although they have not been realized on a large scale. Developing accelerator technology may provide an alternative efficient, robust, and relatively cheap massive-ion beam driver for future particle beam inertial fusion. Here, we propose an accelerator complex for accelerating giant cluster ions, instead of lead or bismuth ions, toward 120 GeV by using induction acceleration over the entire energy region. The proposed two-way multiplex induction synchrotron that is the main accelerator for the giant cluster ion beam would be equivalent to 10 synchrotrons of the same size for a single beam.

Radiation damage in particle accelerator complex for heavy ion inertial fusion

We investigated radiation damages induced by irradiating ions in a particle accelerator for a heavy-ion inertial fusion (HIF) system, because the radio-activation is an unavoidable issue to realize the future HIF power plant. In this study, we estimated the radio-activation at each part of the HIF accelerator. An evaluation using collisions due to Coulomb barrier gives the safer estimation in the radio-activation of the vacuum vessel wall. The estimation results of total cross sections of nuclear reactions between an incident ion and wall elements showed the potential radio-activation parts in the HIF accelerator. We indicated that schematic layouts of two types of HIF accelerators with the nuclear reaction cross section, and the activated area for the HIF accelerator was evaluated.

Development of fuel target implosion simulation system in heavy ion inertial confinement fusion

In inertial confinement fusion (ICF), the DT fuel should be compressed uniformly, and the ion temperature of the compressed DT should reach ~5–10 [KeV]. In order to compress the DT fuel stably to the high density, the implosion non-uniformity should be less than a few percent. In this paper, we present a fuel pellet implosion simulation system O-SUKI code in heavy ion inertial confinement fusion and its application results to parameter studies especially in the driver input pulse. It was found that the rise time period of the main pulse has a significant impact on the fuel implosion performance. We also found that an irradiation timing error of each driver beam induces an enhancement of the implosion non-uniformity, and consequently the driver beam irradiation timing error degrades the fusion energy gain.

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.

Uniformity improvement of fuel target implosion by phase control in heavy ion inertial fusion

A dynamic smoothing method was proposed based on a phase control to stabilize plasma instabilities and smooth plasma non-uniformities. In this paper, the dynamic smoothing method is applied to a spherical fuel target implosion in heavy ion inertial fusion (HIF). We found that the wobbling motion of each heavy ion beam (HIB) axis induces a phase-controlled HIBs energy deposition, and consequently the phase-controlled implosion acceleration is realized, so that the HIBs illumination non-uniformity is successfully smoothed. HIB accelerators provide a well-established capability to oscillate the HIBs axes with a high frequency. In inertial confinement fusion, a fuel implosion uniformity is essentially important to compress the DT fuel and release the fusion energy, and the non-uniformity of the implosion acceleration should be less than a few %. The results in this paper also demonstrate that the wobbling HIBs would provide an improvement in the fusion energy output gain.

On application of wobbler in experiments with cylindrical targets

For the experiments with irradiation of cylindrical targets by intense heavy ion beams which are actual for fundamental and applied researches (laboratory astrophysics, heavy ion inertial fusion, ion therapy, industry) it is necessary to shape the driver beam with hollow geometry. The wobbling method is of interest for such experiments. In the paper one of the problems of the method is considered leading to possible symmetry violation. The results of the simulation of the rotated beam dynamics are presented.

Non-uniformity smoothing of direct-driven fuel target implosion by phase control in heavy ion inertial fusion

We have proposed a dynamic smoothing method based on a phase control to smooth plasma non-uniformities in perturbed plasma systems. In this paper, the dynamic smoothing method is applied to a spherical direct-driven fuel target implosion in heavy ion inertial confinement fusion. We found that the wobbling motion of each heavy ion beam (HIB) axis induces a phase-controlled HIBs energy deposition, and consequently the phase-controlled implosion acceleration is realized, so that the HIBs irradiation non-uniformity is successfully smoothed. HIB accelerators provide a well-established performance to oscillate a HIB axis at a high frequency. In inertial confinement fusion, a fuel implosion uniformity is essentially significant for achieving the DT fuel compression and for releasing the fusion energy, and the non-uniformity of the implosion acceleration should be less than a few %. The results in this paper demonstrate that the wobbling HIBs would provide an improvement in the fuel target implosion uniformity.

Code O-SUKI: Simulation of direct-drive fuel target implosion in heavy ion inertial fusion

The Code O-SUKI is an integrated 2-dimensional (2D) simulation program system for a fuel implosion, ignition and burning of a direct-drive nuclear-fusion pellet in heavy ion beam (HIB) inertial confinement fusion (HIF). The Code O-SUKI consists of the four programs of the HIB illumination and energy deposition program of OK3 (Comput. Phys. Commun. 181, 1332 (2010)), a Lagrangian fluid implosion program, a data conversion program, and an Euler fluid implosion, ignition and burning program. The OK3 computes the multi-HIBs irradiation onto a spherical fuel target. One HIB is divided into many beamlets in OK3. Each heavy ion beamlet deposits its energy along the trajectory in a deposition layer depending on the particle energy. The OK3 also has a function of a wobbling motion of the HIB axis oscillation, and the HIBs energy deposition spatial detail profile is obtained inside the energy absorber of the fuel target. The spherical target implosion 2D behavior is computed by the 2D Lagrangian fluid code coupled with OK3, until just before the void closure time of the fuel implosion. After that, all the data by the Lagrangian implosion code are converted to them for the Eulerian code. The fusion Deuterium (D)–Tritium (T) fuel and the inward moving heavy tamping material are imploded and deformed seriously at the stagnation phase. The Euler fluid code is appropriate to simulate the fusion fuel compression, ignition and burning. The Code O-SUKI 2D simulation system provides a capability to compute and to study the HIF target implosion dynamics. Program summaryProgram Title: O-SUKIProgram Files doi:http://dx.doi.org/10.17632/h8n474wvf5.1Licensing provisions: CC BY NC 3.0Programming language: C++Nature of problem: The nuclear fusion energy would provide one of energy resources for our human society. In this paper we focus on heavy ion beam (HIB) inertial confinement fusion (HIF). A spherical deuterium (D)–tritium (T) fuel pellet, whose radius may be about several mm, is irradiated by HIBs to be compressed to about a thousand times of the solid density. The DT fuel temperature reaches ∼5–10 KeV to be ignited to release the DT fusion energy. The typical HIBs total input energy is several MJ, and the HIBs pulse length is about a few tens of ns. The DT fuel compression uniformity is essentially important to release the sufficient fusion energy output. The DT fuel pellet implosion non-uniformity should be kept less than a few %. The O-SUKI code system provides an integrated tool to simulate the HIF DT fuel pellet implosion, ignition and burning. The HIBs energy deposition detail profile is computed by the OK3 code (Comput. Phys. Commun. 181, 1332 (2010)) in an energy absorber outer layer, which covers the DT fuel spherical shell. The DT fuel is compressed to the high density, and so the DT fuel spatial deformation may be serious at the DT fuel stagnation. Therefore, the O-SUKI system employs a Lagrangian fluid code first to simulate the DT fuel implosion phase until just before the stagnation. Then all the simulation data from the Lagrangian code are converted to them for the Euler fluid code, in which the DT fuel ignition and burning are simulated.Solution method: In the two fluids codes (Lagrangian and Euler fluid codes) in the O-SUKI system the three-temperature fluid model (J. Appl. Phys. 60, 898 (1986)) is employed to simulate the pellet dynamics in HIF. The HIBs energy deposition detail profile is computed by the OK3 code (Comput. Phys. Commun. 181, 1332 (2010)).

Fuel Pellet Alignment in Heavy-Ion Inertial Fusion Reactor

In inertial confinement fusion, 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 heavy ion inertial fusion 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.

New developments of HIF injector

The ultra-high intensity heavy-ion beam is highly pursued for heavy-ion researches and applications. However, it is limited by heavy-ion production of ion source and space-charge-effect in the low energy region. The Heavy-ion Inertial Fusion (HIF) facilities were proposed in 1970s. The HIF injectors have large cavity number and long total length, e.g., there are 27 injectors in HIDIF and HIBLIC is 30 km in length, and the corresponding HIF facilities are too large and too expensive to be constructed. Recently, ion acceleration technologies have been developing rapidly, especially in the low energy region, where the acceleration of high intensity heavy-ions is realized. Meanwhile, superconducting (SC) acceleration matures and increases the acceleration gradient in medium and high energy regions. The length of HIF injectors can be shortened to a buildable length of 2.5 km. This paper will present a review of a renewed HIF injector, which adopts multi-beam linac-based cavities.

Irradiation of materials with short, intense ion pulses at NDCX-II

AbstractWe present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam-driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 1011 ions, 1 mm radius, and 2–30 ns full width at half maximum duration have been created with corresponding fluences in the range of 0.1–0.7 J/cm2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV [megaelectronvolt (106 eV)] He+ ion beam is neutralized in a drift compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment plays an important role in optimizing accelerator performance.

Effect of tapered magnetic field on expanding laser-produced plasma for heavy-ion inertial fusion

AbstractA laser ion source (LIS) is a promising candidate as an ion source for heavy-ion inertial fusion (HIF), where a pulsed ultra-intense and low-charged heavy ion beam is required. It is a key development for a LIS to transport laser-produced plasma with a magnetic field to achieve a high-current beam. The effect of a tapered magnetic field on laser-produced plasma is demonstrated by comparing the results with a straight solenoid magnet. The magnetic field of interest is a wider aperture on a target side and narrower aperture on an extraction side. Based on the experimentally obtained results, the performance of a scaled LIS for HIF was estimated.

Target implosion uniformity in heavy-ion fusion

AbstractIn this paper, the robustness of the dynamic instability mitigation mechanism is first examined, and then the instability mitigation phenomenon is demonstrated in a deuterium–tritium (DT) fuel target implosion by wobbling heavy-ion beams (HIBs). The results presented here show that the mechanism of the dynamic instability mitigation is rather robust against changes in the phase, the amplitude and the wavelength of the wobbling perturbation applied. In general instability would emerge from the perturbation of the physical quantity. Normally the perturbation phase is unknown, so that the instability growth rate is discussed. However, if the perturbation phase is known, the instability growth can be controlled by a superposition of perturbations imposed actively: if the perturbation is induced by, for example, a driving beam axis oscillation or wobbling, the perturbation phase could be controlled and the instability growth is mitigated by the superposition of the growing perturbations. In this paper, we realize the superposition of the perturbation by the wobbling HIBs’ illumination onto a DT fuel target in heavy-ion inertial fusion (HIF). Our numerical fluid implosion simulations present that the implosion non-uniformity is mitigated successfully by the wobbling HIBs illumination in HIF.

Control of fuel target implosion non-uniformity in heavy ion inertial fusion

AbstractIn inertial fusion, one of scientific issues is to reduce an implosion non-uniformity of a spherical fuel target. The implosion non-uniformity is caused by several factors, including the driver beam illumination non-uniformity, the Rayleigh–Taylor instability (RTI) growth, etc. In this paper, we propose a new control method to reduce the implosion non-uniformity; the oscillating implosion acceleration δg(t) is created by pulsating and dephasing heavy-ion beams (HIBs) in heavy-ion inertial fusion (HIF). The δg(t) would reduce the RTI growth effectively. The original concept of the non-uniformity control in inertial fusion was proposed in [Laser Part. Beams (1993) 11, 757–768]. In this paper, it was found that the pulsating and dephasing HIBs illumination provide successfully the controlled δg(t) and that δg(t) induced by the pulsating HIBs reduces well the implosion non-uniformity. Consequently the pulsating HIBs improve a pellet gain remarkably in HIF.

Researches on a reactor core in heavy ion inertial fusion

AbstractIn this paper, a study on a fusion reactor core is presented in heavy-ion inertial fusion (HIF), including the heavy-ion beam (HIB) transport in a fusion reactor, an HIB interaction with a background gas, the reactor cavity gas dynamics, the reactor gas backflow to the beam lines, and an HIB fusion reactor design. The HIB has remarkable preferable features to release the fusion energy in inertial fusion: in particle accelerators HIBs are generated with a high driver efficiency of about 30–40%, and the HIB ions deposit their energy inside of materials. Therefore, a requirement for the fusion target energy gain is relatively low, that would be ~50 to operate an HIF fusion reactor with a standard energy output of 1 GW of electricity. In a fusion reactor, the HIB charge neutralization is needed for a ballistic HIB transport. Multiple mechanical shutters would be installed at each HIB port at the reactor wall to stop the blast waves and the chamber gas backflow, so that the accelerator final elements would be protected from the reactor gas contaminant. The essential fusion reactor components are discussed in this paper.

Uniform fuel target implosion in heavy ion inertial fusion

For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the non-uniformity mitigation mechanisms in the heavy ion beam (HIB) illumination are discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to the radiation energy smoothing for the HIB illumination non-uniformity. The large density-gradient scale, which is typically ∼500μm in HIF targets, also contributes to a reduction of the Rayleigh- Taylor instability growth rate. In HIF a wobbling HIBs illumination would also reduce the Rayleigh-Taylor instability growth and to realize a uniform implosion.

Numerical analysis corresponding with experiment in compact beam simulator for heavy ion inertial fusion driver

Tune depression in a compact beam equipment is estimated, and numerical simulation results are compared with an experimental one for the compact beam simulator in a driver of heavy ion inertial fusion. The numerical simulation with multi-particle tracking is carried out, corresponding to the experimental condition, and the result is discussed with the experimental one. It is expected that the numerical simulation developed in this paper is useful tool to investigate the beam dynamics in the experiment with the compact beam simulator.