Study of electron longitudinal phase space in laser wakefield acceleration via electro-optic streaking technique

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K17998
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 80040:Quantum beam science-related
• Research Institution: National Institutes for Quantum Science and Technology
• Principal Investigator: Huang Kai 国立研究開発法人量子科学技術研究開発機構, 関西光科学研究所 光量子科学研究部, 主任研究員 (30866166)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: high power laser / electron accelerator / beam diagnostics / EO sampling / Longitudinal phase space

Outline of Final Research Achievements

I proposed a brand new electro-optic streaking technique for the single-shot measurement of the electron longitudinal phase space (LPS) in laser wakefield acceleration. A “dog-leg” system composed of two dipole magnet was designed and manufactured. For easier access to the overall self-field information of the electron bunches, the measurement on the transition radiations (TR) from the electron bunches are planned. I have carried out a preliminary experiment to monitor the electron timings outside the plasma. The electron bunches were discovered to have a timing fluctuation of merely 7 fs (rms). This work was published as “K. Huang et al., Applied Physics Express 15, 036001 (2022)” and selected as the spotlight paper of the journal. For the theoretical aspect: I have developed a code covering all the sessions in the LPS. For the next step, I will insert the “dog-leg” into the experimental set-up and measure the LPS of the electron bunch.

Free Research Field

量子ビーム科学

Academic Significance and Societal Importance of the Research Achievements

従来の加速器では、電子バンチのLPSは高周波 (RF) Transverse Deflection Structure (TDS)で測定される。しかし、レーザー駆動の粒子加速の場合、フェムト秒の時間スケールで電子バンチを時間的にキックすることが可能なTDSを構築することは困難である。本研究は、LWFAにおける電子ビームダイナミクスの先駆的な研究となる。EO技術の創造的な応用は、中赤外からTHzまでの波長範囲でのEO結晶の分散特性の研究にも有益である。