[en] In order to asses the fusion research and development, we discussed on proposals which might have possibility to overcome the critical issues of a demonstration fusion reactor. Advanced Tokamak reactor concept and a fast ignition method of laser fusion are proposed to reduce the high capital cost which is common for both of magnetic fusion and inertial fusion. Hopeful divertor concepts are also proposed for both of Tokamak and Helical reactor. These summarized presentations are appended. (author)

[en] The nuclear fusion research was expanded as a research of production of energy from sea water at an oil crisis. The experimental reactor was built at a great cost. History of nuclear fusion researches is explained in details. International Thermonuclear Experimental Reactor (ITER) is a research project with USA, EU, Russia and Japan. ITER is decided to be built in EU. The ITER project and many problems have been investigated in Japan and the progress of negotiations is stated in details. The nuclear fusion energy is one of the future energy sources. Japan should formulate a plan of long period development of energy and the research system. (S.Y.)

[en] Initial stage of linear turbulent heating of plasmas has been investigated by means of Thomson Scattering of ruby laser light with an eight-channel polychromator. In a low density discharge (n sub(e) asymptotically equals 5 x 10¹² cm^-3), an anomalously rapid electron heating was observed to start in association with the onset of the current driven ion acoustic instability. Flat-top velocity distributions of the electrons were observed after the onset of the instability, which was interpreted by the quasilinear diffusion process in the velocity space caused by the turbulent ion acoustic waves. In a high density discharge (n sub(e) asymptotically equals 2 x 10¹⁴ cm^-3), the applied pulse voltage generated skin current distributions disappearing in less than 0.6 μsec, while skin profiles of the electron temperature remained longer, say for 2 μsec. It is concluded that the observed rapid current penetration is also due to the anomalous resistivity caused by the current driven ion acoustic instability. (author)

[en] The application of alkali-metal ion or atomic beams to the diagnostics of magnetically confined plasmas has a long history. Thermionic ion sources are used mostly because of their ease of handling. Fine probing beams and rather large atomic collision cross sections provide good spatial and temporal resolution of the measurements. Among the variety of this kind of diagnosis, two methods are reviewed as typical examples: a heavy ion beam probe (HIBP) and beam probe spectroscopy using a neutral lithium beam (LiBP). (author)

[en] A heavy ion beam probe (HIBP) is a unique diagnostic method to measure the electric potential in magnetically confined high temperature plasmas. Its fine probing beam and well-collimated secondary beam detector give this diagnostic good spatial resolution, which together with the good time resolution make it powerful in probing plasma interior both in steady state and transient state. There are many excellent review papers [for example, 1,2], but these mostly concentrate on HIBP applications in tokamak research. The radial electric field or space potential structure is more important in stellarators or other non-axisymmetric tori, because particle fluxes are intrinsically non-ambipolar in these devices. This paper reports examples of HIBP measurements of potential structures in non-axisymmetric tori - the bumpy torus NBT-1M and the heliotron/torsatron CHS - following brief reviews of the development history and basic principles of the HIBP. (author)

[en] Experiments are described in which the correlation time and fluctuation level of ion waves are measured under the condition of turbulent heating using twin capacitive probes. When the resistivity becomes anomalous, the correlation time becomes shorter, typically several periods of ion waves, and the energy density of the waves is of the order of 0.2.10^-2 n sub(e)T sub(e). The ion heating rate and correlation times of ion waves (electrostatic ion cyclotron waves) are well explained by the quasilinear theories dealing with the stochastic mechanism. The anomalous resistivity is also found to result in the rapid electron heating. (author)

[en] Transition in radial electric field has been observed in CHS plasmas during a combined heating phase of ECH+NBI, using a heavy ion beam probe. The transition occurs in a timescale of a few dozen or a hundred microseconds. Radial current to induce the transition is evaluated by high temporal resolution of the heavy ion beam probe. Neoclassical dependence of radial electric field on a plasma parameter will be discussed to clarify the nonlinearity to allow the transition. (author)

[en] Construction of a large-scale helical device equipped with many measuring instruments is progressing in National Institute for Fusion Science. Aiming at the development of a control system using CAMAC, HIBP measuring system equipped with CHS experimental system was chosen as the object. It is necessary to operate all parts of the apparatus by remote-control. However, there are various functions necessary for the control system of those measuring equipments. Possibly, some of those functions such as those in the vacium-exhaust system can be controlled by a common system. The authors attempted to develop a control system composed of CAMAC controlled by an intelligent crate-controller, and a programmable logic one. In this report, this system, CAMAC and the latter controller are assigned to the real-time control of beam-orbital and the sequence control of the vacuum-exhaust apparatus, respectively. The real-time OS of the intelligent crate controller along with the above system is explained in this report. Further, development of an environment is which graphical user interface available for general-purpose net works is usable and also of a development of measuring control system with VME + VxWorks as well as CAMAC + VAXELN for comparison of the respective control systems are pointed out as the future problems. (M.N.)

[en] By multiple sintering, we have significantly increased the lifetime of the thallium (Tl) zeolite ion source used in single-ended electrostatic accelerators. The obtained lifetime of a small ion source (6.4 mm in diameter and 10 mm long) was about 4400 μAh (70 μAh/mm³ for Tl zeolite). (author)

[en] The heavy ion beam probing system has been constructed for the study of plasma confinement in Nagoya Bumpy Torus (NBT-1/1M). Not only the plasma space potential but also the electron density multiplied by a function of the electron temperature nf(Tsub(e)) can be measured with good spatial resolution. The feedback controlled detection technique and the time resolved fast detection technique are used, depending on the operation mode. The effects of the hot electron beta and the potential on the beam orbit are analyzed. It was confirmed that these effects on the observation points are usually small, and that the hot electron beta can be estimated from the shifts of the primary beam orbits of many cords. (author)