Dr. Y. Shimomura joined the Fusion Research Programme at the Japan Atomic Energy Research Institute (JAERI) in 1971 after studying high temperature plasmas at Osaka University.

From 1973 to 1980, he led the JFT-2a/DIVA project, the first divertor tokamak in the world, and studied impurity control and plasma surface interactions. He developed a reactor-relevant divertor concept, without poloidal field coils inside the toroidal field coils, for INTOR in 1979.

From 1981 to 1991, he worked for the JT-60 Progect as the Head of Experimental Planning and Analysis, later as the Head of the Large Tokamak Experimental Division. He took part in the ASDEX experiment at IPP Garching from December1981 - December 1982 and demonstrated the cold and dense divertor plasma. He also worked for the preparation of the ITER CDA from 1987 and was the Head of the Poloidal Field System Design Unit of the ITER CDA from April 1988 to March 1990.

From July 1992 to July 2001, Dr. Shimomura was the Deputy to the Director of the ITER EDA and coordinated mainly technology R&D activities of the four Parties, Physics Unit and Safety Division at the San Diego Joint Work Site (1992-1999) and at the Naka Joint Work Site ( 1999-2001).

He was appointed International Team Co-Leader in July 2001, and became Interim Project Leader in July 2003.