Interaction Of Particle Beams Research Articles

Preface

The Ninth International Conference on Inertial Fusion Science and Applications (IFSA) was held on September 20-25, 2015 at the Hyatt Regency Bellevue on Seattle’s Eastside, Washington, U.S.A. The event was hosted by the University of California and was organized by the Lawrence Livermore National Laboratory. It brought together more than 370 participants from 16 countries.The goal, as for all previous IFSA Conferences, was to bring together scientists in the fields of inertial fusion science and high-energy-density physics, and their applications. Three hundred twenty seven papers were presented emphasizing the science of high-energy and high-intensity laser, pulsed-power, and particle-beam interactions with matter, the associated high-energy-density physics, and their application to fusion concepts. Results presented included theory, modeling, and experimental results from facilities worldwide.In recent years, significant advances have been made in high-energy-density science using lasers, Z-pinches, and particle beam systems with dramatic technical achievements in areas such as central-hot-spot ignition, fast and impulse ignition, material properties at extreme conditions, warm dense matter, particle acceleration and laser-plasma interactions. For the first time in the laboratory, x-ray driven ignition experiments, performed at the National Ignition Facility (NIF) in the United States, have exhibited self-heating. In the month following the Conference, the first plasma experiments were performed at Laser Mégajoule (LMJ) in France, and ignition scale projects are under way in China and Russia. Other approaches, such as magnetic compression on the Z-machine at Sandia National Laboratories and direct drive experiments at the University of Rochester, have produced exciting new results which were reported on at the Conference.Second-generation petawatt short-pulse laser systems such as the highest-energy petawatt laser systems LFEX (FIREX) in Japan, OMEGA-EP in the United States, PETAL in France, and Vulcan PW in the United Kingdom, have allowed the study of novel approaches to producing and probing high-energy-density matter and exploring alternative ignition schemes. These scientific studies contribute to the physics understanding needed to develop inertial fusion energy as a commercial energy source and were also reported on at the Conference.Third-generation rep-rated and high-energy petawatt lasers are coming on line for strong field science studies and have opened up a new field of relativistic plasma physics. The extreme states achieved in these laser-plasma interactions are relevant to high-intensity x-ray applications, material processing, novel accelerators, and laboratory astrophysics.Recent activities and research in all these fields were discussed in 327 presentations, including three Keynote lectures, two Teller lectures, 21 plenary talks, 135 orals, and 166 posters. The proceedings collected in this volume underwent a rigorous peer-review process. The Editor is thankful to all the authors who agreed to act as referees on papers written by their fellow authors, and who worked both hard and diligently to complete this task in record time. We also thank the Technical Program Committee members who helped make this Ninth IFSA Conference possible.The American Nuclear Society Teller Award was bestowed during IFSA2015 on two key contributors to ICF science, Hiroshi Azechi and Jie Zhang. In addition, prizes were awarded to four students for their excellent presentations.On behalf of the various Committees, we extend our appreciation to everyone who helped make IFSA2015 a great success.

Particle beams in ultrastrong laser fields: direct laser acceleration and radiation reaction effects

Several aspects of the interaction of particle beams with ultrastrong laser fields are discussed. Firstly, we consider regimes when radiation reaction is not essential and it is demonstrated that employing chirped laser pulses, significant improvement of the direct acceleration of particles can be achieved. Results from single- and many-particle calculations of the particle acceleration, in vacuum, by plane-wave fields, as well as in tightly-focused laser beams, show that the mean energies and their spreads qualify them for important applications. Secondly, we investigate the effect of radiation reaction in electron-laser-beam interactions. Signatures of the quantum radiation reaction during the interaction of an electron bunch with a focused superstrong ultrashort laser pulse can be observed in a characteristic behavior of the spectral bandwidth, and the angular spread of the nonlinear Compton radiation on the laser pulse duration. Furthermore, it is shown that the radiation reaction effects can be employed to control the electron dynamics via the nonlinear interplay between the Lorentz and radiation reaction forces. In particular, it is shown that an ultrarelativistic electron bunch colliding head- on with a strong bichromatic laser pulse can be deflected in a controllable way, by changing either the relative phase or the relative amplitude between the two frequency components of the bichromatic field.

Preface: Centennial Physics at Peking University

The Year 2013 is probably as much remarkable for the development of modern physical science in China as it is for School of Physics at Peking University. One hundred years ago, the physics division was born in Peking University, as the very first physics higher education unit having appeared in modern national universities of China. In the first one hundred years, the School has made distinguished contributions to the nation and to the world in both education and academia. As we celebrate the birthday of its first century and set our sights on the next, it is my great pleasure to invite you to this special issue of Frontier of Physics on “Centennial Physics at Peking University”. In 1913, the “WuLi Men” (Physics Division) was established at Peking University, and was later renamed the Department of Physics in 1919. With the reorganization of the Chinese system of higher education in 1952, the new Physics Department of Peking University was created from the merger of the physics departments of Peking University, Tsinghua University and Yenching University. This became the premier center for physics in China. The School of Physics was established in 2001, and includes not only the traditional fields of study in physics, but also related physical sciences. Throughout its history, the School has educated and hosted many prominent physicists, including figures such as Ta-You Wu, C. N. Yang, T. D. Lee, and Kun Huang. Today, the School of Physics includes Physics, Astronomy, Atmospheric & Oceanic Sciences, and Nuclear Science & Technology. Research is devoted not only to the frontiers of fundamental physics but also to the innovation of advanced technology. Major research fields include high energy physics, astrophysics and cosmology, radioactive nuclear physics, high energy-density physics, key technologies for advanced light sources and particle beams, the interaction of particle beams with materials, mesoscopic semiconductor light emission and laser physics, ultrafast physics, optical properties of artificial microstructures and mesoscopic devices, electro-magnetic properties of mesoscopic functional systems, mesoscopic theory and material computation, high-temperature superconductivity physics and devices, nano-material and devices, near-field optics, quantum materials and quantum manipulation, soft condensed matter physics, biophysics, medical physics and imaging, atmospheric physics and the environment, meteorology and climate change, physical oceanography, and many others. The School consists of eleven divisions and seven related research institutes as follows, especially in which Daniel Chee Tsui Laboratory at Peking University was established in 2012, as Prof. Tsui, 1988 Nobel Prize Laureate, became a member of the School.

Alpha Particle Beam Interactions with Fe-Based and FeCo-Based Amorphous Magnets

AbstractSamples of Fe78B13Si1 and Fe66Co18B15Si1 metallic glasses were irradiated with alpha particle beams (W=2.8 MeV) using radiation doses of 1016 and 1017 cm2. Irradiation-induced effects on the magnetic and structural properties of alloy samples were studied by transmission and conversion electron Mbssbauer spectroscopy. The evolution of phases and microstructure during the radiation-induced amorphous-to-crystalline transformation was found to depend on the particle flux and sample composition. Differences between bulk and surface irradiation behaviors were demonstrated.

Efficiency enhancement of Monte Carlo simulation of particle beam interaction by separation of stochastic and continuum contributions

In electron and ion beam lithography, the particle–particle interaction in the drift length of the system imposes a fundamental limitation on the useful current obtainable for a given resolution. This is a classical N-body problem, for which Monte Carlo simulation has proven useful for predicting the size of the effect. Monte Carlo simulation is slow, however, due to the fact that N(N−1)/2 computations of the Lorentz force must be done for N particles at each step. The purpose of this study is to investigate the limitation on computational efficiency. Based on this, an efficient algorithm is proposed and demonstrated. The approach consists of separating the interaction force arising from the average charge distribution from that arising from random fluctuations in charge density. These two contributions are computed separately, and the results combined in a way which eliminates ‘‘end effects’’ arising from a finite particle sample length. The results show that a significant reduction is possible in the number of particles needed to obtain a given level of accuracy. This is expected to result in reduced computation time.

Nondestructive imaging detectors for energetic particle beams

This paper describes the design and discusses initial experimental results produced from a nondestructive, position sensitive particle beam detector. The detector measures the spatial and intensity distribution of a particle beam by determining the position and intensity of secondary electrons or ions produced by particle beam interactions with thin foils ( ∼ 10 μg/cm 2) or wire grids. These secondary charged particles are focused onto an imaging detector using stigmatic ion optics which provide a high degree of correlation between the position of the incident particle beam at the foil and the position of secondary ions at the image sensor. The imaging detector is nonintrusive to the particle beam flux since most of the incident beam passes through the thin foil or around the wire mesh. This detector can monitor particle beam intensities ranging from tens of microamperes down to several hundred particles per second. Image resolution on the order of 5 μ is observed for particle beams having diameters on the order of several millimeters.

Structural fluctuations in small particles

Abstract We present a theoretical analysis of a phenomenon recently observed by high-resolution electron microscopy that involves rapid structural fluctuations in small f.c.c. particles below 10 nm in size. The different energy contributions to the total energy of the particle and the magnitude of the potential energy barrier between different shapes is evaluated and compared with the available energy during particle-beam interactions. The results indicate that the activation energy barrier existing between different shapes is only a few electron volts, whilst a rough estimate indicates that during electron-beam irradiation the available energy may be as much as 100–1000eV.

Analysis of directly driven ICF targets

In this article the current capabilities at DENIM for the analysis of directly driven targets are presented. These include theoretical, computational and applied physical studies and developments of detailed simulation models for the most relevant processes in ICF. The simulation of directly driven ICF targets is carried out with the one-dimensional NORCLA code developed at DENIM. This code contains two main segments: NORMA and CLARA, able to work fully coupled and in an iterative manner. NORMA solves the hydrodynamic equations in a lagrangian mesh. It has modular programs coupled to it to treat the laser or particle beam interaction with matter. Equations of state, opacities and conductivities are taken from a DENIM atomic data library, generated externally with other codes that will also be explained in this work. CLARA solves the transport equation for neutrons, (Boltzmann), as well as for charged particles, and suprathermal electrons (Fokker-Planck), using discrete ordinates and finite element methods in the computational procedure. Parametric calculations of multilayered single-shell targets driven by heavy ion beams are also analyzed. Finally, conclusions are focused on the ongoing developments in the areas of interest such as: radiation transport, atomic physics, particle in cell method, charged particle transport, two-dimensional calculations and instabilities.

Surface Dynamics of Small Particles

ABSTRACTWe investigate the energetics of structure changes in small particles, a phenomena recently observed by high resolution electron microscopy. The energy variations during transformations from a single crystal to symmetric and asymmetric decahedral multiply twinned particle (MTP) structures are evaluated. We examine briefly a few possible energy gain mechanisms during the particle-beam interaction which enable the particles to cross the activation energy barriers and fluctuate between various local energy minima of the morphological potential energy surface.

The summation of Bessel products

We produce in what follows the closed forms for the summation of certain products of Bessel functions pertinent to a number of distinct fields of research, such as the theory of plasma waves, charged particle beam interaction with plasma, and density wave theory in galactic dynamics.

Particle beam interactions with plasmas and their application to inertial fusion

Present day target designs indicate that particle beams with 1-10 MJ and 100-500 TW, focused to intensities around 100 TW/cm2 will be required to ignite targets with gains of 10-100. Due to uncertainties about the symmetry and stability of the implosion, these requirements may change by as much as an order of magnitude as more is learned. The particle beams will interact with target plasmas which have temperatures of several hundred electron volts and densities up to solid density. Under these conditions the main energy-loss mechanism is collisional, however, in the case of electrons, the orbits can be substantially altered by electric and magnetic fields. Experiments with thin foils have measured energy deposition enhancement by a factor of 5-10 with foils mounted in the anode, and by a factor of 20 or more with foils mounted on a stalk extending into the diode.

The use of ion beams to study radiation effects in metals

Abstract Particle accelerators are finding increasing use in the study of materials. This review will concentrate on their application to study radiation damage effects. The first section will deal with the basic interaction of particle beams with solids, the production of defects and their agglomeration, and phenomena such as irradiation-enhanced diffusion and precipitation. The second part of the review complements the recent Contemporary Physics article by J. R. Matthews (1977) which deals with the behaviour of materials in fast reactors. It discusses in some detail the application of particle accelerators to technological problems such as void formation in fast reactor materials and irradiation enhanced creep.