開催報告：日米高エネルギー密度セミナー（Speaker: Dr. Alessio Morace, Osaka University）

日米高エネルギー密度セミナーを６月２１日に開催しました。

大阪大学レーザー科学研究所のAlessio Morace助教をスピーカーとして開催され「プラズマデバイスを用いた強磁場によるプロトンビームの制御」のタイトルでキロジュール級高強度レーザーによるプロトンビームの生成とそのダイナミクスの制御に関し、講演いただきました。

–Speaker–
Dr. Alessio Morace
ILE, Osaka University

–Title–
“Magnetic field dominated proton beam dynamics in focusing plasma devices.”

–Abstract–
High Energy Density Physics is the field of physics dedicated to the study of matter and plasmas in extreme conditions of temperature, densities, and pressures. It encompasses multiple disciplines such as material science, planetary science, laboratory, and astrophysical plasma science. For the latter, High Energy Density states can be accompanied by extreme radiation environments and super-strong magnetic fields. The creation of high energy density states in the laboratory consists in concentrating/depositing large amounts of energy in a reduced mass, typically solid material sample or dense plasma, over a time shorter than the typical timescales of heat conduction and hydrodynamic expansion. Laser-generated, high current-density ion beams constitute an important tool for the creation of High Energy Density states in the laboratory. Focusing plasma devices, such as cone-targets are necessary in order to focus and direct these intense beams towards the heating sample or dense plasma, while protecting the proton generation foil from the harsh environments typical of an integrated high-power laser experiment. A full understanding of the ion beam dynamics in focusing devices is therefore necessary in order to properly design and interpret the numerous experiments in the field. In this work, we report a detailed investigation of large-scale, kilojoule-class laser-generated ion beam dynamics in focusing devices and we demonstrate that high-brilliance ion beams compress magnetic fields to amplitudes exceeding tens of kilo-Tesla, which in turn play a dominant role in the focusing process, resulting either in a worsening or enhancement of focusing capabilities depending on the target geometry.