Low density laser plasma source with various elements applicable to high repetition laser

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K18749
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 14:Plasma science and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Nagai Keiji 東京工業大学, 科学技術創成研究院, 准教授 (30280803)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: レーザープラズマ / レーザーターゲット / 高繰り返しレーザー / 量子線源 / 極端紫外光 (EUV) / 低密度材料 / 高分子電解質 / スズ

Outline of Final Research Achievements

Low density materials can control plasma properties of laser absorption, which can enhance quantum beam generation. The recent practical extreme ultraviolet light (EUV) is the first industrial example of laser plasma source with low density targets. The easy-handling target source based on a hollow sub-millimeter microcapsule was fabricated from polyelectrolyte cationic and anionic surfactant on air bubbles. The lightweight microcapsules acted as a scaffold for surface coating by tin(IV) oxide nanoparticles (22-48%), and then dried. The microcapsules were ablated with a Nd:YAG laser (7.1x10^10 W/cm2, 1 ns) to generate 13.5 nm EUV relatively directed to laser incidence. The laser conversion efficiency (CE) at 13.5 nm 2% bandwidth from the tin-coated microcapsule (0.8%) was competitive compared with bulk tin (1%). The microcapsule aggregates will be utilized as a small scale/compact EUV source, and future quantum beam sources by changing the coating to other elements.

Free Research Field

光エネルギー変換材料

Academic Significance and Societal Importance of the Research Achievements

この成果は13.5 nm のEUVのみならず次世代の 6 nm EUV、炭素イオンビームほか　様々なレーザー誘起量子線用のターゲットに展開できるものである。本技術のニーズは高強度レーザー研究者から特に強く、そうした分野への展開を検討するために、最終年度には、ワークショップでレーザープラズマ型量子線発生の研究者との会合をもち、共同研究の可能性を議論できた。さらに、本研究課題の成果を活用して、通常は高額な装置となるEUV光を、研究室内で利用する試みにも予備的に取り組み始めた。これらを進めることで、本成果は微細加工のみならず、低原子番号材料（生体を含む）の高空間分解能分析、医療応用に繋がる。