No abstract available

[en] Departure from the quasi-neutral condition allows us to apply significant two-fluid effects that impart a new freedom to the design of high-performance fusion plasma. The self-electric field in a non-neutralized plasma induces a strong ExB-drift flow. A fast flow produces a large hydrodynamic pressure that can balance with the thermal pressure of the plasma. Basic concepts to produce a toroidal non-neutral plasma have been examined on the internal-conductor toroidal confinement device Proto-RT. A magnetic separatrix determines the boundary of the confinement region. Electrons describe chaotic orbits in the neighborhood of the magnetic null point on the separatrix. The chaos yields collisionless diffusion of electrons from the particle source (electron gun) towards the confinement region. Collisionless heating also occurs in the magnetic null region, which can be applied to produce a plasma. (author)

[en] Recently, an internal-ring device named Proto-RT (Prototype Ring Trap) was constructed at University of Tokyo, and experiments on the device have been just initiated. The goal of Proto-RT is to explore an innovative way which has a possibility to attain a plasma equilibrium with extremely high-β (β>1) in a toroidal geometry using non-neutral condition. At the first series of the experiments, pure electron plasma (n_e∼10¹² m^-3) is successfully confined inside a separatrix. No disruption is so far observed. The confinement time of the electron plasma is the order of 1 sec. A shear effect of magnetic fields seems to result in longer confinement. The non-neutrality of Δn_e ∼10¹² m^-3 is already beyond the value required to produce an enough self-electric field E in plasma, causing a strong ExB flow thoroughly all over the plasma where the hydrodynamic pressure of the flow is predicted to balance with the thermal pressure of the plasma. (author)

[en] Anomalous heating of ions has been observed in the EXTRAP-T2 reversed-field-pinch (RFP) plasma. Ions are heated primarily in the parallel direction (with respect to the magnetic field), resulting in an appreciable anisotropy of the ion temperature. This observation suggests that the magnetohydrodynamic fluctuations are dissipated primarily by the ion viscosity. (Author)

[en] A feedback control system and an arc power supply capable of controlling a plasma arc current were designed and constructed for generating stable ion beam ranging from pulse to steady operation. The accel current is fed back to the arc current in such a way it can be kept constant. The ion beam current rises to a setting value in 2 ms and is kept constant. The hydrogen ion beam of 1 A, 35 keV was extracted for 1 hour. The stability of both the beam power and the divergence angle are less than ± 0.5 %. (author)

[en] In the neighborhood of a magnetic neutral line, where the magnetic field vanishes, the adiabatic invariants of a charged particle motion are destroyed, and hence the degree of freedom increases. When a radio-frequency electric field is applied, the particle motion becomes strongly chaotic. This effect can be used to produce a heat in a plasma without any collisional process. The kinetic entropy of an electron orbit increases very rapidly by the mixing effect. The velocity distribution is approximated by a Gaussian function, so the thermodynamic entropy production is also estimated. This collision-less heating mechanism enables high-efficiency plasma production at a low gas pressure. (author)

[en] The new, compact data-acquisition system of the reversed field pinch device, REPUTE-1, is reported. Its distinctive feature is high flexibility and easy handling. The interface between the computer and measurement devices is CAMAC. The computer and the CAMAC devices are connected to a CAMAC byte serial highway that transmits setup parameters and acquisition data. The computer carries out setup of CAMAC devices and data acquisition automatically by use of CAMAC parameters and the acquisition data base. The maintenance tools for the data base are also provided. The computer system, which consists of a ''TOSBAC DS-600,'' has been in operation for REPUTE-1 since 1985

[en] The object of the experiment was to study the rapid further heating of a tokamak plasma and its influence on confinement. For this purpose, a high-voltage theta-pinch pulse was applied to a tokamak plasma and production of a high-temperature (keV) plasma was ensured within a microsecond. The magnetic pulse is applied at the plasma current maximum parallel or antiparallel to the study toroidal field. In either case, the pulsed field quickly penetrates the plasma and the plasma resistivity estimated from the penetration time is about 100 times larger than the classical. A burst of energetic neutrals of approximately 1 μs duration was observed and the energy distribution had two components of the order of 1 keV and 0.1 keV in the antiparallel case. Doppler broadening measurement shows heating of ions to a temperature higher than 200 eV; however, the line profile is not always Maxwellian distribution. The X-rays disappear at the moment of applying the magnetic pulse and reappear about 100 μs later with an intensive burst, while both energy levels are the same (approximately 100 keV). (author)

[en] A reversed ultra-fast theta-pinch using a Blumlein circuit is applied to an ordinary tokamak plasma to provide of further heating. A large amplitude magnetic wave is excited and propagates radially into the plasma and is expected to heat it turbulently by its passage, the plasma cross-section remaining unchanged. A preliminary experiment in a straight machine showed some interesting results. A small, fat torus has been constructed whose major diameter is 50 cm and minor is 24 cm. The conducting shell also serves as the thetatron coil. The toroidal magnetic field is, 7 kG and the plasma current of 30 kA flows for about 10 ms. The Blumlein line charged to 100 kV is closed at the time of the plasma current maximum. The induced azimuthal electric field is estimated to be 0.4 kV/cm along the tube wall in the case of vacuum. The rise time of the magnetic field is 200 ns. (author)

[en] As a marker for prostatic cancer, a prostate-specific antigen was purified from human prostatic tissues. Double antibody radioimmunoassay utilizing immune reaction was developed on the basis of the purified prostatic antigen (PA). Measurement results have revealed that PA radioimmunoassay is much better than prostatic acid phosphatase (PAP) radioimmunoassay in the diagnosis of prostatic cancer