The Novel ''Controlled Intermediate Nuclear Fusion'' and its Possible Industrial Realization as Predicted by Hadronic Mechanics and Chemistry

In this note, we propose, apparently for the first time, a new type of controlled nuclear fusion called "intermediate" because occurring at energies intermediate between those of the ''cold'' and ''hot'' fusions, and propose a specific industrial realization. For this purpose: 1) We show that known limitations of quantum mechanics, quantum chemistry and special relativity cause excessive departures from the conditions occurring for all controlled fusions; 2) We outline the covering hadronic mechanics, hadronic chemistry and isorelativity specifically conceived, constructed and verified during the past two decades for new cleans energies and fuels; 3) We identify seven physical laws predicted by the latter disciplines that have to be verified by all controlled nuclear fusions to occur; 4) We review the industrial research conducted to date in the selection of the most promising engineering realization as well as optimization of said seven laws; and 5) We propose with construction details a specific {\it hadronic reactor} (patented and international patents pending), consisting of actual equipment specifically intended for the possible industrial production of the clean energy released by representative cases of controlled intermediate fusions for independent scrutiny by interested colleagues.Comment: 32 pages, 5 figures. Journal of Applied Sciences, in pres

Breakup reactions of 90MeV 9Be

SIGLEAvailable from British Library Document Supply Centre- DSC:DX84154 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Extremely high-intensity laser interactions with fundamental quantum systems

The field of laser-matter interaction traditionally deals with the response of atoms, molecules and plasmas to an external light wave. However, the recent sustained technological progress is opening up the possibility of employing intense laser radiation to trigger or substantially influence physical processes beyond atomic-physics energy scales. Available optical laser intensities exceeding 10^{22}\;\text{W/cm^2} can push the fundamental light-electron interaction to the extreme limit where radiation-reaction effects dominate the electron dynamics, can shed light on the structure of the quantum vacuum, and can trigger the creation of particles like electrons, muons and pions and their corresponding antiparticles. Also, novel sources of intense coherent high-energy photons and laser-based particle colliders can pave the way to nuclear quantum optics and may even allow for potential discovery of new particles beyond the Standard Model. These are the main topics of the present article, which is devoted to a review of recent investigations on high-energy processes within the realm of relativistic quantum dynamics, quantum electrodynamics, nuclear and particle physics, occurring in extremely intense laser fields.Comment: 58 pages, 26 figures, version accepted by Reviews of Modern Physic

Studies of magnetised and non-local transport in laser-plasma interactions

The application of magnetic fields in inertial fusion experiments has led to renewed interest in fully understanding magnetised transport in laser-plasma regimes. This motivated the development of a new laser magnetohydrodynamic code PARAMAGNET, written to support investigations into classical magnetised transport phenomena and laser propagation in a plasma. This code was used to simulate laser-underdense plasma interactions such as the pre-heat stage of magneto-inertial fusion. Alongside these simulations, this thesis will present analytic focusing and filamentation models derived from magnetohydrodynamics extended with classical magnetised transport coefficients. These results showed the focal length and filamentation growth length shortened with magnetisation, a result of the magnetisation of the thermal conductivity. Further investigation of the transport properties using the diffusion approximation kinetic code IMPACT showed significant deviation of the growth rate at intermediate values of magnetisation and non-locality, inexplicable using fluid models. The kinetic code result motivated exploring the influence of the high-order anisotropies of the distribution function (in terms of spherical harmonics), ignored in conventional approximations. By using a recursive matrix inverse method, corrections to the transport coefficients including all orders of the electron distribution expansion were found. Analysis of the conductivity, resistivity and thermoelectric coefficients showed deviation by up to 50% from the classical form at intermediate magnetisation and nonlocality. The diffusive approximation of the IMPACT simulations was insufficient to capture the transport behaviour present in the theoretical high order calculation. Modern inertial fusion experiments work in regimes that are non-local and susceptible to significant focusing exacerbated by magnetisation. The resulting filamentation has detrimental implications to laser absorption and the modified non-local transport behaviour is a possible source of error in simulations. The complex interplay between non-locality and magnetisation in transport suggests using more terms of the spherical harmonic expansion in closures of plasma equations. Particular consideration is given to the implications to inertial fusion experiments. Together these results suggest the necessity of including non-local magnetised transport in the modelling of high-energy-density laser plasma experiments.Open Acces

High-Performance Software for Quantum Chemistry and Hierarchical Matrices

Linear algebra is the underpinning of a significant portion of the computation done in the modern age. Applications relying on linear algebra include physical and chemical simulations, machine learning, artificial intelligence, optimization, partial differential equations, and many more. However, the direct use of mathematically exact linear algebra is often infeasible for the large problems of today. Numerical and iterative methods provide a way of solving the underlying problems only to the required accuracy, allowing problems that are many magnitudes larger to be solved magnitudes more quickly than if the problems were to be solved using exact linear algebra. In this dissertation, we discuss, test existing methods, and develop new high-performance numerical methods for scientific computing kernels, including matrix-multiplications, linear solves, and eigensolves, which accelerate applications including Gaussian processes and quantum chemistry simulations. Notably, we use preconditioned hierarchical matrices for the hyperparameter optimization and prediction phases of Gaussian process regression, develop a sparse triple matrix product on GPUs, and investigate 3D matrix-matrix multiplications for Chebyshev-filtered subspace iteration for Kohn-Sham density functional theory calculations. The exploitation of the structural sparsity of many practical scientific problems can achieve a significant speedup over the dense formulations of the same problems. Even so, many problems cannot be accurately represented or approximated in a structurally sparse manner. Many of these problems, such as kernels arising from machine learning and the Electronic-Repulsion-Integral (ERI) matrices from electronic structure computations, can be accurately represented in data-sparse structures, which allows for rapid calculations. We investigate hierarchical matrices, which provide a data-sparse representation of kernel matrices. In particular, our SMASH approximation can construct and provide matrix multiplications in near-linear time, which can then be used in matrix-free methods to find the optimal hyperparameters for Gaussian processes and to do prediction asymptotically more rapidly than direct methods. To accelerate the use of hierarchical matrices further, we provide a data-driven approach (where we consider the distribution of the data points associated with a kernel matrix) that reduces a given problem's memory and computation requirements. Furthermore, we investigate the use of preconditioning in Gaussian process regression. We can use matrix-free algorithms for hyperparameter optimization and prediction phases of Gaussian process. This provides a framework for Gaussian process regression that scales to large-scale problems and is asymptotically faster than state-of-the-art methods. We provide an exploration and analysis of the conditioning and numerical issues that arise from the near-rank-deficient matrices that occur during hyperparameter optimizations. Density Functional Theory (DFT) is a valuable method for electronic structure calculations for simulating quantum chemical systems due to its high accuracy to cost ratio. However, even with the computational power of modern computers, the O(n^3) complexity of the eigensolves and other kernels mandate that new methods are developed to allow larger problems to be solved. Two promising methods for tackling these problems are using modern architectures (including state-of-the-art accelerators and multicore systems) and 3D matrix-multiplication algorithms. We investigate these methods to determine if using these methods will result in an overall speedup. Using these kernels, we provide a high-performance framework for Chebyshev-filtered subspace iteration. GPUs are a family of accelerators that provide immense computational power but must be used correctly to achieve good efficiency. In algebraic multigrid, there arises a sparse triple matrix product, which due to the sparse (and relatively unstructured) nature, is challenging to perform efficiently on GPUs, and is typically done as two successive matrix-matrix products. However, by doing a single triple-matrix product, reducing the overhead associated with sparse matrix-matrix products on the GPU may be possible. We develop a sparse triple-matrix product that reduces the computation time required for a few classes of problems.Ph.D

Study of transport of laser-driven relativistic electrons in solid materials

With the ultra intense lasers available today, it is possible to generate very hot electron beams in solid density materials. These intense laser-matter interactions result in many applications which include the generation of ultrashort secondary sources of particles and radiation such as ions, neutrons, positrons, x-rays, or even laser-driven hadron therapy. For these applications to become reality, a comprehensive understanding of laser-driven energy transport including hot electron generation through the various mechanisms of ionization, and their subsequent transport in solid density media is required. This study will focus on the characterization of electron transport effects in solid density targets using the state-of- the-art particle-in-cell code PICLS. A number of simulation results will be presented on the topics of ionization propagation in insulator glass targets, non-equilibrium ionization mod- eling featuring electron impact ionization, and electron beam guiding by the self-generated resistive magnetic field. An empirically derived scaling relation for the resistive magnetic in terms of the laser parameters and material properties is presented and used to derive a guiding condition. This condition may prove useful for the design of future laser-matter interaction experiments

Interatomic potentials: Achievements and challenges

Interactions between atoms can be formally expanded into two-body, three-body, and higher-order contributions. Unfortunately, this expansion is slowly converging for most systems of practical interest making it inexpedient for molecular simulations. This is why effective descriptions are needed for the accurate simulation of many-atom systems. This article reviews potentials designed towards this end with a focus on empirical interatomic potentials not necessitating a-priori knowledge of what pairs of atoms are bonded to each other, i.e., on potentials meant to describe defects and chemical reactions from bond breaking and formation to redox reactions. The classes of discussed potentials include popular two-body potentials, embedded-atom models for metals, bond-order potentials for covalently bonded systems, polarizable potentials including charge-transfer approaches for ionic systems and quantum-Drude oscillator models mimicking higher-order and many-body dispersion. Particular emphasis is laid on the question what constraints on materials properties ensue from the functional form of a potential, e.g., in what way Cauchy relations for elastic tensor elements can be violated and what this entails for the ratio of defect and cohesive energies. The review is meant to be pedagogical rather than encyclopedic. This is why we highlight potentials with functional forms that are sufficiently simple to remain amenable to analytical treatments, whereby qualitative questions can be answered, such as, why the ratio of boiling to melting temperature tends to be large for potentials describing metals but small for pair potentials. However, we abstain for the most part from discussing specific parametrizations. Our main aim is to provide a stimulus for how existing approaches can be advanced or meaningfully combined to extent the scope of simulations based on empirical potentials