Table of contents

Preface

14^th Kudowa Summer School "Towards Fusion Energy", Kudowa-Zdrój, Poland, 4^th – 8^th June 2018

kudowaschool.ipplm.pl

The Kudowa Summer School "Towards Fusion Energy" takes place every two years in summer, usually in June, in Kudowa-Zdrój: a small resort city at the Polish-Czech border and is organized by the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland. Multinational audience, mostly PhD students, as well as Master students and young scientists from all over the world, have an opportunity to gather in order to broaden their knowledge of plasma and fusion physics, participating in lectures presented by outstanding and world-renowned lecturers working in the field of nuclear fusion.

Last edition of Kudowa Summer School was focused on following topics:

plasma basics and fusion energy

inertial confinement fusion

magnetic confinement fusion

plasma-diagnostics and technology.

Most of the participating students presented short presentations of their current work – the special jury awarded three best contributions with special prizes. Moreover, every student has been given a chance to publish a paper based on given talk.

This issue of Journal of Physics: Conference Series is the selection of the most interesting works submitted by participants of the School.

14^th Kudowa Summer School in numbers:

5 days

24 hours of speeches in total

17 lectures

27 student talks

46 participants.

Director of the School: J. Ongena

List of Scientific Committee and Local Organizing Committee members are available in this pdf.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The calculation of ray tracing for microwaves at 36 GHz frequency depending on the different maximum values of density was made. The calculation showed when rays hit or do not hit into the horn antenna shifted at angle 60° degrees with respect to the axis of the radiating horn antenna. In addition, the calculated and experimental measurements of the phase shift dependence in time for the through and inclined probing were performed. The use of refraction during interferometry can give additional information about plasma when the through probing interferometry is impossible.

Interferometry is a widely used active diagnostic method for measurements of physical properties of plasmas. In case of axial symmetry of probed objects an Abel inversion can be used to retrieve plasma density profiles from phase shifts reconstructed from interferograms. This approach is based on the assumption of the diagnostic beam propagating along a straight line. However, it is well known that in case of inhomogeneous media the refraction process affects the diagnostic beam trajectory resulting in an inaccuracy of the retrieved density structure. In order to deal with this unfavourable effect a more sophisticated approach needs to be employed. In this paper a special iterative algorithm is proposed to deal with this issue. This algorithm turns the inversion procedure into series of iterations, where the appropriate distribution of plasma density is found by following the diagnostic beam actual trajectory during its propagation through the inhomogeneous medium. The assumption of axially symmetric plasma distribution still applies. The respective trajectories are calculated using the ray tracing method. This method also allows to use the paraxial wave equation. This iterative algorithm was tested on simulated data with different configurations of plasma density proving its functionality. Results from the simulated data analysis show that using this approach the effect of refraction can be fully compensated and plasma density is thus recovered accurately. Comparison with the results obtained only by the Abel inversion as such is provided for illustration.

Test particle diffusion in a random electric field across uniform magnetic field is studied using analytical approach and direct numerical simulation. Our approximation describes particle trapping and is able to reproduce an asymptotically zero diffusion coefficient for infinite Kubo number, i.e. dimensionless correlation time. For large, but finite, correlation times the subdiffusive scaling relation for asymptotic diffusion coefficient is obtained. The considered approach also recovers the known scaling relation for small correlation times. The accurate method to take into account finite Larmor radius effects is demonstrated.

Extreme Light Infrastructure (ELI) is a large-scale European project, still in the development stage, offering parameters of laser drivers required for multiple applications (femtosecond pulse duration, ultra-relativistic laser intensities ∼ 10²² - 10²³ W/cm²), however studies of ion acceleration in the given intensity regime are still in the very early stages and require a deeper understanding of the processes occurring during laser-matter interactions to maximize the efficiency of ion acceleration. The purpose of this work is a numerical examination of the properties of carbon ion beams produced during the interaction of an ultra-intense laser beams (of intensities ∼ 10²¹ – 10²³ W/cm² and pulse duration order of femtoseconds, predicted to be available at ELI-NP, Romania) with C¹² target. The dependence of ion beam parameters, such as intensity, energy spectrum, maximum and average ion energy and spatial distribution of ion charge density, on laser pulse parameters (mainly intensity) and the target thickness is investigated. The possibility of generation of high intensity, GeV energy ion beams in the foregoing conditions is demonstrated. The obtained results can be useful for research in high energy-density physics, nuclear physics or medical applications of ion beams.