Development of hot plastically deformed Si X-ray mirrors

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K18775
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 16:Astronomy and related fields
• Research Institution: Tokyo Metropolitan University
• Principal Investigator: Ezoe Yuichiro 首都大学東京, 理学研究科, 准教授 (90462663)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: X線望遠鏡 / シリコン / 高温塑性変形

Outline of Final Research Achievements

We have developed hot plastically deformed Si X-ray mirrors for future X-ray astronomy missions. A thin Si wafer is ideal as an X-ray mirror substrate because of its stiffness and lightness. How to bend the fragile Si wafer has been an issue. We deformed Si wafers into a conical shape using hot plastic deformation method. A Si wafer was pressed between convex and concave dies at high temperature near melting point of Si above 700 deg C. For the first time with this method, we have succeeded to shape a Si wafer into the conical shape and to demonstrate X-ray imaging with the single mirror. The measured angular resolution was about 30 arcsec in the central part of the mirror but more than 1 arcmin at edges. By improving the shapes of the dies and deformation conditions, further improvements can be expected in the near future. Furthermore, we have established smooth Pt coating on the Si wafer using atomic layer deposition method.

Free Research Field

X線天文学

Academic Significance and Societal Importance of the Research Achievements

本研究の目的は将来のX線天文衛星に向けて、軽量かつ解像度の良い新たな望遠鏡を開拓することである。日本独自のSi 基板を高温でプレス変形する手法で、本研究で世界で初めて本手法で円錐鏡を試作して、角度分解能で基板中央部で約30秒角という、一つの目標である<1分角を達成した。基板端では治具の噛み合わせが悪く改良を要するが、形状を改善した治具の製作にも企業の協力により成功しており、近い将来の衛星搭載に向けて大きな期待が持てる結果である。また Si 表面への原子層堆積法を用いた膜付けも世界に先駆けて行った。宇宙用だけでなく、X線レントゲンなどの医療や微量分析などの地上応用も可能と考えている。