The use of electrical discharges and plasmas for sterilization is reviewed. Plasmas generated by a silent discharge, a pulse discharge, and a radio frequency discharge under atmospheric pressure have been used for sterilization. Furthermore, a microwave plasma, a radio frequency plasma, and a low temperature plasma with hydrogen peroxide under low pressure conditions have been also used for sterilization. Sterilization results from injury caused by the discharge current, and from the reaction of species affected by the discharge. A silent discharge with air or oxygen is most effective for the sterilization. Nitrogen discharge also has a significant effect, however, argon discharge does not have a significant effect.

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This paper briefly reviews the effects of electric fields, air ions, and corona discharge on plants. From the middle of the eighteenth century, electric fields and air ions have been applied to plants both in the field and under laboratory conditions. Although many studies have reported beneficial effects, the results have been inconsistent, and the electrical conditions leading to definite benefits cannot so far be predicted. High electric fields have been reported to damage plants by flowing the induced currents caused by corona discharge from the tips. Since the investigations have been continued, the results have been controversial and contradictory. There remains no firm theory governing electrophysiology in plants.

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In an attempt to replace chemicals for weed control, high voltage spark discharge has been applied. With the application of high voltage, discharge takes place, and current flows through the stem and root. Microscopic observation indicates that cells are damaged. The electrical resistance of the damage plant’s stems and roots decreased significantly. Several different types of apparatus were constructed, and field test results show the effectiveness of electrical discharge for weed control.

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The biological effects of extremely low frequency electric fields on animals are reviewed with emphasis on studies of the nervous system, behavior, endocrinology, and blood chemistry. First, this paper provides a histrical overview of studies on the electric field effects initiated in Russia and the United States mainly regarding electric utility workers in high voltage substations and transmission lines. Then, the possible mechanisms of electric field effects are explained using the functions of surface electric fields and induced currents in biological objects. The real mechanisms have not yet been identified. The thresholds of electric field perception levels for rats, baboons, and humans are introduced and compared. The experimental results concerning the depression of melatonin secretion in rats exposed to electric fields are described.

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Research on the electrostatic chemical application system has been carried out for the purpose of improving spray deposition and reducing spray drift. By means of corona discharge or electrostatic induction, particles of agricaltual chemicals become electrostatically charged. Many electrostatic sprayers are developed and tested. The results suggested that these sprayers improved the spray deposition onto plants or plant models. Several electrostatic sprayers are currently utilized.

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The so-called “Yamase” accompanied by very low temperatures and dense fog results in not only bad crop harvests especially rice, but also traffic confusion and accidents during the summer season from the Sanriku Coast to Shimokita Peninsula in the part of northern Japan facing the Pacific Ocean. Effective counterplots against these disasters are strongly expected to be realized by farmers and many citizens. We have invented an electrostatic fog-liquefier in order to solve these problems by dissipating fog artificially. In this paper, we describe the principle of fog dissipation by means of corona discharge, and demonstrate fog and white vapor dissipation experiments not only in a laboratory, but in the field also. Bad odor abatement by means of this newly invented apparatus is also related in detail.

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The stability of mirror-confined plasmas is reviewed. The equilibrium of mirror-confined plasmas is first briefly discussed. Then, MHD stability is studied based on an energy priciple with the paraxial approximation and flute and ballooning interchange-mode equations are derived. The effects of E×B rotation due to an ambipolar electric field and the finite Larmor radius of ions on MHD stability are briefly described. Alfven ion cyclotron instability driven by the temperature anisotropy of ions, and E×B drift shear stabilization of electrostatic drift waves due to an ambipolar electric field are reported.

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A parallel mapping algorithm for plasma particle codes on vector-parallel computers is shown with the use of an extended Abe-Nishihara vectorization algorithm. It is scalable not only for performance but also for size of problem. A plasma particle code employing this algorithm achieves scalable parallel performance on the distributed-memory-type vector-parallel computer VPP300 and the SX-4, the shared- and distributed-memory-type vector-parallel architecture. On such a code, parallel performance is determined by four ratios. First is a ratio between the number of arithmetic operations and the number of elements which are to be transferred to other processors. Second is a peak ratio between the arithmetic flop/s and communication MB/s performance. Third is a ratio between efficiency of the arithmetic and communication performance. Fourth is a ratio of the number of meshes to particles. Among those four ratios, the three ratios except for the third one are determined uniquely by the property of the code or computer. Therefore, the third ratio is an important issue to design and select parallel computers for the plasma particle codes.

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Based on the various studies on the ignition characteristics, the feedback control algorithm for ignition burn has been developed for a safe operation and diagnostic integration design of ITER. A set of the diagnostic systems for core burn control are selected and a fail-safe control algorithms has been proposed to prevent the unsafe operation caused by the diagnostic failure. Some feature in the reduced cost of ITER Is also presented.

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An 89 GHz quasi-optical Electron Cyclotron Heating (ECH)/Current Drive (ECCD) system has been installed on the WT-3 tokamak. In order to investigate the effect of localized ECH/ECCD on the MHD instabilities, this system is designed to focus the micro-wave beam into a small focal spot with the radius about 1cm in the plasma center. This radius is smaller than the inversion radius of the sawtooth oscillation observed in WT-3. Utilizing this feature, the experiment on control of sawtooth oscillation by on-axis current drive have been performed. Stabilization of sawtooth by counter-ECCD is observed when the power deposition is localized inside the inversion radius. This result may be due to the decrease in current density near the magnetic axis. For the optimal coupling of the micro-wave to obliquely propagating waves at the plasma surface, a linear-elliptical polarization converter has been installed recently. This polarization converter may raise the effective current drive efficiency by a factor of 1.5 for the injected micro-wave power.

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To examine the effects of ferritic steel on error field, ripple reduction and plasma properties (especially for improved confinements), Advanced Material Tokamak EXperiment (AMTEX) is planned for JFT-2M. The AMTEX program consists of the test of toroidal field ripple reduction with ferritic inserts and that of the compatibility between ferritic steel and the tokamak plasma. To reduce fast ion losses due to toroidal field ripple, the ripple amplitude and its toroidal mode number have to be reduced. The guideline of the design for the reduction in ripple amplitude (δ) by inserting Ferritic Boards (FB) is as follows; the wider and thicker FB should be positioned far from the plasma and be located just under the toroidal field coil. Elimination of a central part of the FBs is effective in reducing a second harmonic ripple amplitude. Since the ferritic steel easily saturates by the toroidal magnetic field, the δ depends on the toroidal magnetic field. The JFT-2M Vacuum Vessel (VV) will be remodelled using ferritic steel for the plasma-matching test. Since the relative magnetic permeability of the ferritic steel is around two, the effect of the ferritic steel VV on plasma equilibrium is rather small. A simple port design can reduce any ripple amplitude of the fundamental mode but cannot reduce that of higher modes.

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