Fusion Program in Japan and Prospect of Inertial Fusion

AU0019439

SadaoNAKAI Institute of Laser Engineering, Osaka University Yamada-oka, Suita, Osaka 565 Japan

Development of nuclear fusion as a practical energy source could provide great benefits for all mankind. This fact has been widely recognized and this task could be good example to pursue the goal with worldwide collaboration and friendship. Fusion energy development is one of the big scientific programs in Japan. Both Magnetic Fusion Energy (MFE) and Inertial Fusion Energy (IFE) are proceeded aiming to achieve clean, abundant and safe fusion energy for the future human society on the earth.

Fusion Program in Japan ^ In "July 1975 the Atomic Energy Commission of Japan laid down the second phase basic program of fusion research and development. JT-60 (the Break-even Plasma Test Device) was constructed by the Japan Atomic Energy Research Institute (JAERI) and marked in 1987 the. achievement of its major goals as given in the second phase program. With the upgraded machine JT-60U, experiments are addressing the improvement of reversed shear plasma performance and non-inductive current drive in high performance/2^ The research on small and medium-sized devices in universities also contributed to the significant progress achieved in many aspect of fusion plasma. In 1988 IPP Nagoya University was converted to National Institute of Fusion Science (NIFS) to construct the Large Herical Device (LHD) which was completed and started the plasma experiment in 1998. For the Inertial Fusion, the world largest laser facility GEKKO XII was completed in 1983 and high density compression up to 600 times solid density was achieved in 1989 which demonstrate physical feasibility of laser implosion fusion. The third phase basic program is going to be implemented. The principal objectives of this phase are the achievement of the self-ignition condition, the realization of a long burn and the formation of the reactor technology bases required for the prototype fusion reactor development. A Tokamak fusion experimental reactor is to be developed to play a central role in attaining the goals of this phase. At the same time, the importance is recognized to establish a reliable energy confinement scaling law in other magnetic fusion concepts and a reliable gain scaling in inertial fusion. Both ITER in Tokamak and National Ignition Facility (NIF) in the US laser fusion program are the facilities to pursue the similar goal with that of the third phase basic program of Japan. The overview of the fusion energy R&D in Japan is shown in the chart. Tokamaks: JAERI (JT-60) Kyushu Univ. (Triam) h- Helical Devices: NIFS (CHS, LHD) "MEF—i_ Reverse FieW pinch. Tokyo Univ_ (REPUTE) „ . _ — Compact Tori: Universities Fusion Energy 1 *— Mirror Device: Tsukuba (GAMMA-10) R&D in Japan - r— Laser Fusion: ELE Osaka Univ. (GEKKO-12) — IFE—j : ETL-MITI (Ashura) Driver Developments: Universities

35 Prospect of Inertial Fusion The basic physics of Inertial Confinement (compression and ignition of small fuel pellet containing deuterium and tritium) is becoming increasingly well understood. The research on implosion physic is focused on establishing the reliable energy gain scaling with evaluation on the tolerable non-uniformity of laser irradiation and fuel pellet. The key issues are (1) formation of hot spark by direct, indirect and hybrid drive implosion, (2) sensitivity of fusion gain to implosion stability, (3) improvement of the integrated code for investigating gain scaling and high gain pellet design, and (4) investigation on new concept for ignition and burn such as volume ignition and fast ignition. Inertial fusion ignition, burn and energy gain are expected to be achieved within the first decade of next century with Megajule laser facilities which are under construction in the USA and France. The progress of implosion and relevant technologies give us feasible prospect and require us to examine a strategic approach toward IFE development. The design study for a laser fusion power plant KOYO has been conducted as a joint program of universities, national laboratories and industries in Japan. Fusion power plant design studies, together with the technical breakthrough in the field of Diode Pumped Solid State Laser (DPSSL) indicate that IFE power plant are feasible and have attractive cost, safety, and environmental features. The review book "Energy from Inertial Fusion" was published from IAEA (1995) as a results of international collaborative work of 80 experts from around the world in recognition of the growing importance of IFE research/3^ [However, international cooperation in ICF has been rather limited both in scope and in participation. The reason for the limited international cooperation in this field is that portions of ICF programs had remained classified in some countries. Recently, many restrictions have been lifted and it is now possible to notice a significant growth of international cooperation in this area. Part of the mission of the IAEA is to support and to encourage progress towards the development of thermonuclear fusion as a new energy source. The continuation of international cooperation in two possible approaches to nuclear fusion-MCF and ICF- is of major importance to any breakthrough in the utilization of this potentially unlimited source of energy. J (Hans Blix, Foreward by Director General for "Energy from Inertial Fusion") A consultant group was organized in 1997 by IAEA to help the Agency keep abreast of current in making future program plans in IFE. The final report has been submitted to IAEA recommending to take action for IFE research promotion in planning, technical meetings, coordinated research, public information, and equipment sharing and manpower development. It should be also noticed that laser fusion energy development will be proceeded jointly with industrial photonics research and development because of the richness of spinoff of laser fusion technology.

References 1) National Policy for Promoting Fusion Research and Development, (Third Phase Basic Program of Fusion Research and Development) Atomic Energy. Commission, Japan, June 9, 1992 2) 17th IAEA Fusion Energy Conference, International Atomic Energy Agency Yokohama, Japan, 19-24 October 1998 3) Energy from Inertial Fusion, IAEA, Vienna, 1995