Faculty Members

Main research themes and their characteristics

「Laser-produced extreme ultraviolet (EUV) source and applications」

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　One of the key technologies that support the network society is the miniaturization of integrated circuits. The light source used in the reduction projection exposure system has a shorter wavelength, and liquid immersion method and multiple exposure method have been developed for the reduction. However, these manufacturing processes are extremely complicated resulting in a cost problem. Furthermore, it is difficult to apply the multiple exposure method to manufacture chips having complicated circuits such as logic and central processing unit. Under these circumstances, several national projects started to develop a clean and highly efficient extreme ultraviolet light source with a wavelength of 13.5 nm. As a result, a method of irradiating a tin droplet with a two-wavelength double pulse laser as shown in Fig. 1 was developed (a patent of Osaka University). Now, the EUV light source developed along this way is spreading to the production of logic circuits with a node width of several nm.
　Since the photon energy of extreme ultraviolet light is about 10 eV, which is larger than the band gap energy of various materials. That enables to directly ionize substances. Such high-powered light sources have great expectations as a tool that will open new hollizon in material process research. Currently, under the "Collaboration project with Osaka University on advanced light technology", we are conducting joint research on the material process of laser plasma emission extreme ultraviolet light.

「Laser-driven neutron source and n-radiography」

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　In recent years, neutrons have been increasingly used as a nondestructive inspection probe source not only in science but also in technology fields such as physical properties, materials, devices, biology, foods, drug discovery, nuclear material research, but also in product development and manufacturing sites in industry. Since neutrons have a high sensitivity to light elements such as hydrogen, they can be used in combination with radiographs using X-rays as a probe source to prevent the formation of large composites (eg, bag-shaped steel plates joined with adhesive, oil flowing inside iron pipes).
　Research n-reactors that have been used in the field of neutron research from the past have to meet high-level safety regulations. Therefore, there is a demand for the "on-demand" compact neutron sources that can generate neutrons with the required energy and number when needed. Upon this background, the "construction of basic technology for compact neutron sources and their industrial application" (JST/A-STEP Project (2016-2019)). It has been promoted and has achieved the highest level of neutron generation in the world. Currently, under the "Collaboration project with Osaka University on advanced optical technology", we are conducting research and development on laser-driven neutron sources.

Major academic publications

H. Nishimura,他17名 “Energy transport and isochoric heating of a low-Z, reduced-mass target irradiated with a high intensity laser pulse”, Physics of Plasmas 18, 022702 (2011).

A. Yogo, (9 authors) H. Nishimura, (17 authors), ”Boosting laser-ion acceleration with multi-picosecond pulses”, Scientific Reports 7, (2017) 42451.

H. Nishimura, Y. Arikawa, Y. Abe, A. Yogo, “Laser-driven neutrons and relevant diagnostics ”, Plasma and Nuclear Fusion research, 95 (2019) 3-10.

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