The idea here is to use large relative velocities of electrons and nuclei in accelerator beams to increase the probability of fusion. The function of the electrons is to both screen the positive charge and to produce an increased parallel pinching current. The increase in reaction probability is estimated using the Darwin magnetic interaction energy approach.
Relativistic fluid dynamics and the theory of relativistic detonation fronts are used to estimate the space-time dynamics of the burning of the D-T fuel in Laser driven pellet fusion experiments. The initial "High foot" heating of the fuel makes the compressed target transparent to radiation, and then a rapid ignition pulse can penetrate and heat up the whole target to supercritical temperatures in a short time, so that most of the interior of the target ignites almost simultaneously and instabilities will have no time to develop. In these relativistic, radiation dominated processes both the i…
Recently laser induced fusion with simultaneous volume ignition, a spin-off from relativistic heavy ion collisions, was proposed, where implanted nanoantennas regulated and amplified the light absorption in the fusion target. Studies of resilience of the nanoantennas was published recently in vacuum. These studies are extended to nanoantennas embedded into a polymer, which modifies the nanoantenna's lifetime and absorption properties.
Relativistic Six-Fluid Rotating-Plasma Force-Balance Equilibria for p-11B Fusion Conditions in Spherical Tori
Beijing ENN Fusion Energy Science and Technology Co., Ltd.（北京恩诺聚变能源科学与技术有限公司）；Beijing Key Laboratory of High Magnetic Field Spherical Torus Fusion Energy（北京市高磁场球环聚变能重点实验室）；Hebei Key Laboratory of Compact Fusion（河北省紧凑型聚变重点实验室）
Energetic electrons are of interest in many types of plasmas, however previous modeling of their properties has been restricted to the use of linear Fokker-Planck collision operators or non-relativistic formulations. Here, we describe a fully non-linear kinetic-equation solver, capable of handling large electric-field strengths (compared to the Dreicer field) and relativistic temperatures. This tool allows modeling of the momentum-space dynamics of the electrons in cases where strong departures from Maxwellian distributions may arise. As an example, we consider electron runaway in magnetic-con…
The radial neoclassical fluxes of electrons in the 1/nu regime are calculated with relativistic effects taken into account and compared with those in the non-relativistic approach. The treatment is based on the relativistic drift-kinetic equation with the thermodynamic equilibrium given by the relativistic Maxwell-Jüttner distribution function. It is found that for the range of fusion temperatures, T_e<100 keV, the relativistic effects produce a reduction of the radial fluxes which does not exceed 10%. This rather small effect is a consequence of the non-monotonic temperature dependence of the…
Fast ignition of fusion targets by laser-driven electrons
在充分考虑集体磁效应和背景等离子体流体动力学响应的基础上，对预压缩聚变靶中的快电子输运和能量沉积进行了混合粒子模拟.内爆快速点火配置的实际点火结果显示在最近的实验中发现的光束发散度增加[J. S. Green等人，物理修订信函100，015003（2008）]和由于通过高级PIC模拟预测的轮廓陡化而导致的电子动能的减少[B. Chrisman等人，Phys.Plasmas 15，056309（2008）]。研究了靶点火与注入电子能量、锥尖到致密核的距离、相对论电子束的初始发散角和动能的关系。我们发现，光束准直大大降低了点火能量的锥形引导燃料配置假设在这里。
Fusion energy will be the ultimate clean energy source for mankind. One of the most visible concerns of the future fusion device is the threat of deleterious runaway electrons (REs) produced during unexpected disruptions of the fusion plasma. Both efficient long-term algorithms and super-large scale computing power are necessary to reveal the complex dynamics of REs in a realistic fusion reactor. In the present study, we deploy the world's fastest supercomputer, Sunway TaihuLight, and the newly developed relativistic volume-preserving algorithm to carry out long-term particle simulations of 10…
We present particle-in-cell (PIC) simulations of minority energetic protons in deuterium plasmas, which demonstrate a collective instability responsible for emission near the lower hybrid frequency and its harmonics. The simulations capture the lower hybrid drift instability in a regime relevant to tokamak fusion plasmas, and show further that the excited electromagnetic fields collectively and collisionlessly couple free energy from the protons to directed electron motion. This results in an asymmetric tail antiparallel to the magnetic field. We focus on obliquely propagating modes under cond…
Beam filamentation instability drives deuterium-tritium fusion with polarized neutron emission
State Key Laboratory of Nuclear Physics and Technology, Peking University（北京大学核物理与技术国家重点实验室）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；College of Physics, Sichuan University（四川大学物理学院）；Beijing Laser Acceleration Innovation Center（北京激光聚变创新中心）
The understanding of the physics of lasermatter interactions in the strongly relativistic regime is of fundamental importance. In this article, a new mechanism of fast electron generation at the vacuum-solid boundary of intense laser pulse interaction with overdense plasma is described. It is one that has no analogue in classical, non-relativistic laser-plasma interactions. Here, conclusive proof is provided that the key contribution to the fast electron generation is given by the zero points of the vector potential. We demonstrate that the new mechanism leads to scalings for the fast electron…
The potential formation of multi-mega-ampere beams of relativistic "runaway" electrons (REs) during sudden terminations of tokamak plasmas poses a significant challenge to the tokamak's development as a fusion energy source. Here, we use state-of-the-art modeling of disruption magnetohydrodynamics coupled with a self-consistent evolution of RE generation and transport to show that a non-axisymmetric in-vessel coil will passively prevent RE beam formation during disruptions in the SPARC tokamak, a compact, high-field, high-current device capable of achieving a fusion gain Q > 2 in deuterium-tri…
High-energy-density flows through dense matter are needed for effective progress in the production of laser-driven intense sources of energetic particles and radiation, in driving matter to extreme temperatures creating state regimes relevant for planetary or stellar science as yet inaccessible at the laboratory scale, or in achieving high-gain laser-driven thermonuclear fusion. When interacting at the surface of dense (opaque) targets, intense lasers accelerate relativistic electron beams which transport a significant fraction of the laser energy into the target depth. However, the overall la…
The onset and evolution of magnetic fields in laboratory and astrophysical plasmas is determined by several mechanisms, including instabilities, dynamo effects and ultra-high energy particle flows through gas, plasma and interstellar-media. These processes are relevant over a wide range of conditions, from cosmic ray acceleration and gamma ray bursts to nuclear fusion in stars. The disparate temporal and spatial scales where each operates can be reconciled by scaling parameters that enable to recreate astrophysical conditions in the laboratory. Here we unveil a new mechanism by which the flow …
Plasma Screening Effects in Stark Broadening: A Fully Relativistic Close-Coupling Approach
College of Science, Xi’an University of Science and Technology（西安科技大学理学院）；National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics（计算物理国家重点实验室，应用物理与计算数学研究所）；HEDPS, Center for Applied Physics and Technology, Peking University（高能密度物理研究中心，应用物理与技术中心，北京大学）；College of Science, Xi’an University of Architecture and Technology（西安建筑科技大学理学院）
For the simulation of disruptions in tokamak fusion plasmas, a fluid model describing the evolution of relativistic runaway electrons and their interaction with the background plasma is presented. The overall aim of the model is to self-consistently describe the nonlinear coupled evolution of runaway electrons (REs) and plasma instabilities during disruptions. In this model, the runaway electrons are considered as a separate fluid species in which the initial seed is generated through the Dreicer source, which eventually grows by the avalanche mechanism (further relevant source mechanisms can …
Self-consistent modelling and qualitative comparison of mildly relativistic runaway electron dynamics with a closed flux surface formation model during tokamak startup
During disruptions in fusion-grade tokamaks like ITER, large electric fields are induced following the thermal quench (TQ) period which can generate a substantial amount of Runaway Electrons (REs) that can carry up to 10 MA current with energies as high as several tens of MeV [1-3] in current quench phase (CQ). These runaway electrons can cause significant damage to the plasma-facing-components due to their localized energy deposition. To mitigate these effects, impurity injections of high-Z atoms have been proposed [1-3]. In this paper, we use a self-consistent 0D tokamak disruption model as …
Developing avoidance or mitigation strategies of runaway electrons (RE) in magnetic confinement fusion (MCF) plasmas is of crucial importance for the safe operation of ITER. In order to develop these strategies, an accurate diagnostic capability that allows good estimates of the RE distribution function in these plasmas is needed. Synchrotron radiation (SR) of RE in MCF, besides of being one of the main damping mechanisms for RE in the high energy relativistic regime, is routinely used in current MCF experiments to infer the parameters of RE energy and pitch angle distribution functions. In th…
Demonstration of full-scale spatio-temporal diagnostics of solid-density plasmas driven by an ultra-short relativistic laser pulse using an X-ray free-electron laser
Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in which DT fuel is first compressed to high density and then ignited by a relativistic electron beam generated by a fast (< 20 ps) ultra-intense laser pulse, which is usually brought in to the dense plasma via the inclusion of a re-entrant cone. The transport of this beam from the cone apex into the dense fuel is a critical part of this scheme, as it can strongly influence the overall energetics. Here we review progress in the theory and numerical simulation of fast electron transport in the context of Fast Ignition. Im…
The properties of high energy density plasma are under increasing scrutiny in recent years due to their importance to our understanding of stellar interiors, the cores of giant planets$^{1}$, and the properties of hot plasma in inertial confinement fusion devices$^2$. When matter is heated by X-rays, electrons in the inner shells are ionized before the valence electrons. Ionization from the inside out creates atoms or ions with empty internal electron shells, which are known as hollow atoms (or ions)$^{3,4,5}$. Recent advances in free-electron laser (FEL) technology$^{6,7,8,9}$ have made possi…
