A new method for determining the electron density of a thin plasma by means of Fabry-Perot interferometry is proposed. The interferometer consists of two plasma layers and dielectric material surrounded by two plasma layers. The transmittance of electromagnetic waves across the interferometer is calculated, and Fabry-Perot resonances are demonstrated. It is shown that the plasma density can be determined based on the measurement of the resonance frequency when the width of a plasma layer is known.

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The absorption rate of heat microwave power for plug ECRH (electron cyclotron resonance heating) in the GAMMA 10 tandem mirror is calculated in three ways over a wide range of plasma density. These methods include ray-tracing calculation, analytic estimation and full-wave Maxwell simulation. The results correlate very closely with each other. The full-wave Maxwell simulation is found to be a powerful method to evaluate the microwave power deposition for ECRH. It also predicts the power deposition in the region of ω_c < ω for beach heating.

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An analytical method to evaluate spatio-temporal change in the current density profile directly from the motional Stark effect (MSE) diagnostic is applied to a discharge, where a neo-classical tearing mode (NTM) appeared and was stabilized by electron cyclotron current drive (ECCD). The analysis clearly shows a spatially localized decrease in current density at the magnetic island location, implying a decrease in bootstrap current due to a flattening of the pressure profile within the island. When the NTM is stabilized after the start of the ECCD application, an increase in current density at the island location is observed.

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This article presents recent progress in magnetic measurements of magnetic confinement systems. “Signal drift” in the integrator for magnetic measurements is one of the major problems for plasma control and the estimation of equilibrium parameters in long-pulse operation. In addition, the durability of sensors such as a magnetic probe, a flux loop, etc., under fusion neutron irradiation environments is also important. The present status of the developments of a long-pulse integrator and a new magnetic sensor are reported.

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Large-scale simulation research is the most important and effective method to reveal the physical mechanisms in the complex systems such as fusion plasma. The current state of the development and history of the supercomputer system of Theory and Computer Simulation Center of National Institute for Fusion Science are summarized and the concept of the next generation simulator is introduced.

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The progress of large scale scientific simulation environment in JAERI is briefly described. The expansion of fusion simulation science has been played a key role in the increasing performances of super computers and computer network system in JAERI. Both scalar parallel and vector parallel computer systems are now working at the Naka and Tokai sites respectively, and particle and fluid simulation codes developed under the fusion simulation project, NEXT, are running on each system. The storage grid system has been also successfully developed for effective visualization analysis by remote users. Fusion research is going to enter the new phase of ITER, and the need for the super computer system with higher performance are increasing more than as ever along with the development of reliable simulation models.

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Tremendous progress has been made in the enhancement of the peak performance of high-end supercomputers like the Earth Simulator. Tera-Flops machines are being very common, and the key to their success is large-scale parallel processing. From the programmers’ point of view, the difficulty of parallel programming has remained the same in comparison with the progress made in hardware systems. In this paper, we outline recently developed parallel programming software technologies, and discuss the direction of their future development.

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High performance magnetically confined plasma is realized by having structures in plasmas, in which different elementary processes with different time and spatial scales act synergistically with each other. Research based on large scale simulation is then essential to understand such complex hierarchical plasmas. We discuss the underlying physical process of structural plasmas and present the prospects for future numerical simulations which cover a wide dynamical range.

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Recent progress of large scale simulation study in laser fusion research at Osaka University is briefly reviewed in connection with supercomputer development. Present vector-parallel computers have allowed us to proceed to three-dimensional simulations from two-dimensional ones without any difficulties in both radiation-hydro and particle codes. The molecular dynamic(MD) method used mostly in microscopic simulations can also be applied to large-scale macroscopic simulations. Some simulation results are shown with figures. Various attempts to realize highperformance network computing are also presented, including an application of large scale MD simulations using the Lagrangian Particle D³ (Dynamic Domain Decomposition) method to a supercomputer network connected by Super SINET, as well as to integrated fast ignition simulations with the use of originally developed DCCP (Distributed Computing Collaboration Protocol), and to the EUV (Extreme Ultra Violet) simulation GRID.

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Computer simulation research has greatly changed its feature due to the appearance of supercomputers and their recent revolutionary development. This paper briefly reviews how plasma simulation has developed under such a background in the information technology and what kind of problems will be attacked in the coming future, in regard to basic plasma physics research, including self-organization of an MHD plasma and collisionless reconnection. Especially, the importance of cross-hierarchy simulation is discussed.

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A new formula has been derived to describe the energy spectrum of sputtered atoms from a target material bombarded by light ions. We assume that sputtered atoms bombarded by low-energy light ions are mainly primary knock-on atoms which are created by large-angle backscattered light ions. The escape processes of recoil atoms are estimated on the basis of the Falcone-Sigmund model. The new formula has the dependence on the incident energy of a projectile. We have compared the new formula with simulation results calculated with ACAT code for a Fe target material bombarded by 50eV, 100eV and 500eV D⁺ ions. Good agreements are found for 50eV and 100eV D⁺ ions.

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