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Suprathermal electrons which carry a seed current are generated by non-resonant parametric decay instability during the initial phase of lower-hybrid current startup in the JIPP T-IIU tokamak. From the numerical analysis it is found that parametrically excited lower-hybrid waves at the lower side-band can bridge the spectral gap between the thermal-velocity region and the low-velocity end of the pump power spectrum.

A new technique for local magnetic field measurement in a bumpy torus NBT‐1M (which is a magnetic plasma confinement device) has been developed using a rapid‐frequency‐scan (RAFS) laser system combined with sodium atomic beam probing. The RAFS laser beam excites the sodium D1 transition in the plasma cavity, and the Zeeman pattern is determined with laser fluorescence spectroscopy in a single laser shot. From the Zeeman splitting, the transient magnetic field distribution in the plasma, produced by electron cyclotron resonance heating (ECH), is measured with an accuracy of ±3.2%, a spatial resolution of 5 mm, and a temporal resolution of 5 μs.

The small-scale density fluctuations have been studied by both millimeter (2 mm) and sub-millimeter (337 µm) wave scattering technique in JIPP T-II plasmas. Experiments were performed in two types of plasma: tokamak and stellarator plasmas. In both plasmas, the density fluctuations are localized in outer region of the plasma column, and show the characteristics of the drift wave mode turbulence. The density fluctuation level is \(\tilde{n}/n_{0}{\simeq}1{-}1.5\%\) around the plasma edge, and this value is inversely proportional to the mean electrondensity. Further, the dependence of the fluctuation level on the plasma parameters is studied and compared with the scaling law of the energy confinement time of the plasma. The diffusion coefficient estimated from the density fluctuation is about one third of the global diffusion coefficient.

The use of a toroidal magnetic field as a lens system is proposed for producing an intense ion beam. The characteristics of the lens system are obtained both analytically and numerically. Some examples of ray-trajectories are presented for different focal lengths. The system is applicable to neutral beam injection heating and micro-pellet implosion for nuclear fusion, and to other fields such as ion beam X-ray lasers.

The surfaces of TiC (20 μm) coated limiters were investigated after four-month plasma exposure with tokamak and stellarator type discharges in JIPP T-II. Three types of surface damage were observed as 1. 1) a large melted spot having many macrocracks, 2. 2) a large exfoliated surface of the coating and 3. 3) a color changed region without exfoliation of the coating. The position of damages observed on the ring limiters and the rail limiter revealed that the damages of 2) and 3) were associated with the asymmetric cross-sectional shape of the stellarator type plasma. The quantitative AES analysis was performed for identification of surface impurities (Si,P,C, etc.) transported from the plasma and for depth composition analysis of the limiters. It was found that C atoms were depleted from the subsurface region and 0 atoms accumulated to produce a thick Ti-oxide layer (1500 A). The thickness of the oxide and the amount of retained Fe atoms in the subsurface region were also found to be associated with the asymmetric shape of stellarator type plasma.

Since the foundation of FPDC in April 1985, a system (FPDC-SRX) for the synchrotron radiation experiment at UVSOR facility of IMS, Okazaki, has been developed for the purpose of establishing calibration techniques of optical components, detectors and spectrometers for plasma diagnostics. The SRX is composed of a beam line (BL5B), a primary monochromator of plane grating type and a calibration chamber. The present status of the SRX is described, although the calibration chamber is being designed.

Current driven by injecting lower hybrid waves has been observed in low-density plasmas in the JIPP T-II. It is confirmed that RF-driven current is generated by momentum transfer from lower hybrid waves to suprathermal electrons with an energy of 8–25 keV. The driving efficiencies in tokamak and stellarator configurations are 1 kA·kW−1 and 0.3 kA·kW−1, respectively, at a power level of 40 kW. Enhanced electron cyclotron emission due to pitch-angle scattering of RF-driven suprathermal electrons is observed, and spikes in loop voltage and X-ray bursts appear coincidentally. In a long RF-pulse, these rapid changes advance to relaxation oscillations. It is concluded that the pulsating changes originate in the instantaneous scattering of RF-driven suprathermal electrons by the unstable waves excited at an anomalous Doppler resonance.

A six‐channel HCN laser interferometer system has been developed for the measurement of the electron density profile in the JIPP T‐IIU tokamak. The fringe shift of the probe beam is directly read out using a reference beam, the frequency of which is Doppler shifted by 50 kHz with a rotating grating. The optical configuration is of the Michelson interferometer type, of which reflecting mirrors are directly attached on the wall of the vacuum vessel. An effective area of the optical window is only φ40 mm. This optical configuration enables us to make the electron density profile measurements by the multichannel laser interferometer with a single small optical window.

A novel technique to measure the magnetic field strength is demonstrated, which is based on blow‐off beam probing combined with Doppler‐tuned laser spectroscopy. The field strength is determined from the Zeeman splitting of the LiI resonance line (670.8 nm) with good time and spatial resolutions (Δt

The technique of laser fluorescence spectroscopy (LFS) was exploited for the study of surface phenomena during ion-beam bombardment by observing the transient change of the velocity distribution functions from pure iron and iron-oxide targets. It was shown that the surface binding energy of compound as well as pure materials could thus be measured. In addition, the LFS technique was expanded to the VUV region by observing the fluorescence signal of carbon atoms sputtered from a graphite target.

A new method using both techniques of a neutral beam and spectroscopy has been developed to measure the spatial electron density profile of a plasma. This neutral beam probing technique utilizes the photons emitted by impact excitation of the probing lithium beam with plasma electrons. The spatial electron density distribution of the plasma of Te approximately 10 eV, ne approximately 1011 cm-3 has been determined from the measurements of the local photon flux and beam intensity by using the excitation rate coefficient calculated from the available cross-section data. The comparison of these results with those of conventional methods proves this new method is of practical use in the space-resolved measurements of plasma parameters, especially when a Langmuir probe is no longer usable. The cross sections for excitation of the Li beam in collisions with He, Ar and H2 have been also measured and used to estimate the neutral lithium beam intensity.

All the X-ray lines associated with K-shell from an iron plasma have been observed. Transition wavelengths of the He-like resonance series lines up to 1s6p-1s 2 have been determined for the first time. The structures of Kα He-like and Kβ Li-like satellites are described in detail. A highly resolved Kα spectrum of FeXXIV and FeXXV has been observed and the plasma parameters were defer-mined from the intensity ratios of intercombination line γ, dielectronic satellite j and satellite q due to inner-shell excitation to resonance line w and the line broadening of w , i.e., n e ≃10 21 cm -3 , T e ≃2.2 keV, the ionization temperature T z ≃0.8 keV and \(T_{i}\lesssim 4\) keV. These parameters show that the plasma is mainly under the transient ionizing condition. Comparison between the observed and calculated intensity ratios among the He-like resonance series lines in C–R model gives an evident proof for the ionizing plasma.

The principle of Project MACETIE and the preliminary experiment are described. The basis of our plan is the thought that the goal of controlled thermonuclear fusion may be accessible by the multistage alternating processes of adiabatic compression and irreversible expansion of plasma. In the latter process, the plasma compressed by a strong magnetic field is expanded into a region of weaker magnetic field. A static consideration of this expansion suggests that plasma temperature will not change appreciably in this process, and a second adiabatic compression of plasma in the weak field may further increase its temperature. Preliminary experiments are being carried out to examine the foregoing principle of irreversible expansion.

Spase and time resolved Mach-Zebnder interferometer is applied to study a slow theta pinch plasma. Methods of timing operations and experimental arrangements are described. The plasma is pinched in the third half cycle of discharge period. The interferogram shows that the peak electron density varies from about 1 x 1016 to 1 x 1017 cm-3 as the filling gas pressure is varied from 25 to 400 mtorr. The radial distribution of shell structure is observed when a small reverse bias field is added. The relaxation time of this field is longer at the lower gas pressure. In the pressure range of higher than 40 mtorr, a flute-type instability appears. But no drift motions are observed. Interferograms show various modes of instabilities. The loss rate of the total number of electrons is estimated and the result is in good agreement with a theoretical model of steady magnetohydrodynamic fluid.

For the measurement of a profile of spectral line, a high dispersive monochrometer with an Echelle-grating and 12 channels of photoelectric devices using thin glass sheets, to separate the line profile are constructed. The measured resolving power is about 2×105 and the linear dispersion at the image plane is 1.2 mm/A. This instrument is applied to measure the ion temperature of MACETIE device by using the line of He II 4686 A.

An apparatus dedicated to characterizing the VUV and soft x‐ray optical elements was fabricated, and a preliminary test on its performance was made in the soft x‐ray region with a grasshopper monochromator at the Photon Factory. The results demonstrated that quantitative evaluation of diffraction efficiency of a grating could be easily performed using the apparatus.

Spatially resolved Fe Kα spectra in the wavelength range of 1.7–2.0 A (FeII‐XXVI) and 1.91–1.95 A (FeII‐XIX) are first observed in a single shot with low‐resolution Johansson and high‐resolution Johann type crystal spectrometers, respectively. The spectra show the evident proof that the vacuum spark plasma has two different structures. One is a thermalized point plasma (≲10 μm) with high temperature (Te ∼2 keV) and high density (ne ∼1021 cm−3). The spectrum contains x‐ray lines from FeXXIII‐XXVI. The other is an extended plasma (∼3 mm) associated with nonthermal electrons, where the region of intense emission of Kα lines from FeIII‐XX shifts toward the cathode with the increase of the ionic charge.

A new method combining Li0‐beam probing and spectroscopic techniques has been developed to measure local magnetic fields in a bumpy torus. A collimated thermal Li0 beam is injected into the plasma. The Zeeman pattern of the lithium resonance radiation (22S–22P, 6708 A) is observed with a Fabry–Perot interferometer. The strength of the local magnetic field is determined from the splitting between two π components of the 22S1/2–22P1/2 transition with the spatial resolution of about 7 mm. The magnetic fields from 2 to 4 kG were measured with accuracy of ±2%. This method is applicable to plasmas of a line‐integrated electron density below 5×1012 cm−2.

In order to clone hepatitis C (blood-borne non-A, non-B hepatitis) virus, lambda gt11cDNA library was constructed from RNA extracted from 100 liters serum collected from 1,047 donors with elevated ALT levels and negative for hepatitis B virus-DNA. The library was immunoscreened on Y1090 cells with pooled serum obtained from patients with acute hepatitis C or chronic hepatitis C. By screening 29 clones specific for Japanese hepatitis C infection were isolated. The specificity of these clones for hepatitis C infection was determined by panels constructed in 3 laboratories. Of these, 12 clones were specific for American hepatitis C infection as well. The nucleotide sequence (201 bp) of one of them was determined to be unique compared to known human viruses including hepatitis A virus, hepatitits B virus and hepatitis D virus. Southern blot analysis showed the absence of the sequence of the human genome in the clone. The predicted amino acid sequence is rich in residues of lysine, arginine, glutamic acid and asparagine, while lacking leucine, cysteine and methionine.

A lambda gt11-random-primed-cDNA clone specific for chronic hepatitis C was isolated from pooled serum presumably infected by hepatitis C virus. The translation product of the clone detect 50% of patients with chronic hepatitis C in 4 test panels but none of the patients with acute hepatitis C, other liver diseases or normal controls was positive for the peptide. The nucleotide sequence of the cDNA clone, the size of which is 66 bp, has no homology to the complete sequences of known human viruses such as adenovirus, coxsackievirus, rhinovirus, immunodeficiency virus type 1, Epstein-Barr virus, polioma virus, poliovirus, papilloma virus, parvovirus, papovavirus, varicella-zoster virus, yellow fever virus, endogenous retrovirus, T-cell lymphotropic virus types I, II, and III Japanese encephalitis virus, and hepatitis A, B, and D viruses. Probably only one or two epitopes are present on the molecule encoded by the clone as the peptide consists of only 22 amino acid residues.

Turbulent spectrum of ion waves excited by an electron current is investigated experimentally, where electron drift velocity is measured directly by the rotatable Langmuir probe.

The effective scattering of an ion beam by the ion wave turbulence is investigated experimentally. The results are compared with the values predicted theoretically.

A simple diagram method is applied to obtain the time evolution of the electron temperature from the time history of the impurity line radiation which appears during the early phases of lower hybrid current startup in the JIPP T-IIU tokamak. This method makes it possible to survey the dependence of the time behavior of impurity emission on various plasma parameters (impurity influx rate, impurity confinement time, etc.). The electron temperature thus obtained agrees well with that derived from the temperature-sensitive line ratio and from Thomson scattering.

A metal-film bolometer has been developed for reliable measurements of the radiation power from high-temperature plasmas. Its sensitivity and time response were improved by reducing the absorber thickness (10 µm) to the minimum limit in order to sufficiently absorb photons with high energies up to 3 keV. In addition, this detector has well-defined thermal characteristics. The deviation of the measured value arising from thermal cooling was investigated by numerically solving a heat conduction equation associated with the detector. The calculated results could explain the thermal characteristics well for a temporally constant power (at calibration) and showed that the deviation of the measured radiation power from its calculated value could be reduced by a precise correction (to the extent of 0.5%).

The characteristics of four crystals (LiF(200), Ge(220), LiF(220) and Quartz(2023)) for a Johann type crystal spectrometer with Photo Diode Array have been investigated from observations of FeKα1,2 characteristic X-ray. The results are tabulated with their resolution power and relative sensitivities. They were applied also to the X-ray spectroscopic measurements of a high-temperature plasma. The fine structure of the iron oxygen-like Kα lines has been resolved by the Quartz(2023) crystal.

The spatial profiles of electron density in Nagoya Bumpy Torus (NBT) have been measured with a fast neutral Li beam probing, which utilizes the photon emission due to the electron impact excitation of the injected atoms. It is shown that plasmas are well contained inside the hot electron annuli. The attenuation of thermally injected Li atoms has been measured for the estimation of electron density as a cross check.

The characteristics of a Johann-type crystal spectrometer with a photodiode array (PDA) are described. The crystal used is LiF(200) with a bending radius of 100 cm, and the sensitivity of the PDA is measured for X-rays of 4 to 17 key. The collection efficiency η of charges created in the PDA is determined as a function of the X-ray energy E(keV): η=-0.026E+0.68. An asymmetrical spectral profile is observed when a monochromatic X-ray beam is incident on the PDA with an angle larger than 40°. The sensitivity of the spectrometer is also calibrated against a conventional X-ray tube. The PDA is used for the observation of X-ray lines from a high-temperature plasma in a vacuum spark. The resultant Fe Kα spectrum shows a spread over several channels due to blooming, when compared with that recorded on Kodak no-screen X-ray film.

A 10-channel grating polychromator has been developed and applied for the measurements of the second harmonic electron cyclotron emission from the JIPP T-IIU tokamak plasma. The frequency resolution measured at 150 GHz is about 3 GHz which corresponds to the spatial resolution of 1.8 cm near the center of the plasma column. The grating efficiency is about 80% for S-polarization around 160 GHz. Its excellent time resolution, Δt≤2 µs, is favorable for studying MHD activities in hot plasmas. It has been found from the measurements in JIPP T-IIU that the grating polychromator is a powerful diagnostic tool for the measurements of electron temperature of the plasma.

By introducing into the single-collision model a flux-attenuation factor both in the incoming flux and in the outgoing flux, together with a reduced particle energy, we have derived more comprehensive analytical expressions for the number and energy reflection coefficients for all incident-target-atom combinations, leading to a simple explicit representation of the reflection flux under certain approximations. This gives the general qualitative tendency of the light-particle reflection, while a more quantative knowledge should be obtained from computer simulations or analytical approaches including numerical calculation for multiple collisions.

The magnetic field strength has been obtained from the Zeeman splitting. Thermal He atoms, as an impurity, were injected into a low density (n e∼5×1010 cm-3) hydrogen plasma produced by electron cyclotron resonance. A singlet line at 6678 Å from He atoms excited by the plasma electrons splits into a normal Zeeman triplet in the magnetic field. The line profile was measured with a high resolution Fabry-Perot interferometer. This diagnostic allows the determination of the Zeeman splitting at magnetic fields as low as 1.2 kG, lower than which the splitting is masked by the Doppler broadening of the injected atoms.

The efficiency vs operation voltage characteristics of a channel electron multiplier (CEM) with a negative voltage applied to the entrance cone are investigated in detail. In this negative bias operation, an abnormal increase in efficiency with operation voltage is found, arising from two main mechanisms. One is the change in potential distribution in the cone with the applied voltage. This is because the probability of secondary electrons ejected from the cone being pulled into the channel depends on the potential distribution in the cone. The other is the ionization of particles by leakage electrons from the gap between the CEM exit and the electron collector. Methods of solving these problems are also described.

The characteristics of a thermistor, a metal-film bolometer, and a pyroelectric detector were investigated with the aim of attaining a highly reliable bolometric measurement. The spurious signal which appears on a pyroelectric detector was sufficiently eliminated by setting a mask close to the detector, thus avoiding the direct incidence of photons at the electrode. Whether a signal was true or false could be determined from the integrated value of the signal. Calibrations were performed with a HeNe laser in consideration of reflections on the detector surface. No time drift was observed on the sensitivity determined in such a way. The radiation power measured with a pyroelectric detector agreed within 10% with that measured with a calibrated metal-film bolometer.

A high-current lithium ion beam of a few mAcm-2 with an energy of 12 keV and a minimum beam divergence of about 1.2° has been produced by using an ion source of the discharge type. Characteristics of the lithium ion beam regarding the intensity and divergence were experimentally investigated in detail. A lithium neutral beam has been produced using a sodium neutralizer. The neutralization efficiency of the lithium ion beam in the energy range of 2–15 keV was about 80% with a neutralizer at a vapor pressure of 1.7×10-3 Torr. A mass analysis was performed when a mixed discharge of lithium and argon was used. The ratio of R (argon-ion current/lithium-ion current) became less than 0.1 at the oven temperature of the ion source to about 700°C. The applicability of a fast neutral lithium beam to plasma probing is discussed.

The spectral line profiles produced by neutral hydrogen atoms have been measured using a high resolution Fabry-Perot Interferometer. The Hα line 6563 Å is found to have an asymmetric profile in non-magnetized and low density plasmas. The line profile calculated taking into account the fine structure of the Hα line shows a reasonable agreement with the experimental results. The atom temperature obtained from the Doppler broadening is about 0.1 eV.

Successful oscillation of a tunable, high-power argon excimer laser is reported. The wavelength was tuned from 124.5 to 127.5 nm with a spectral width of 0.3 nm. The output power of 2.2 MW, obtained at the line center, is 3 orders of magnitude larger than the value reported previously by Wrobel et al. [Appl. Phys. Lett. 36, 113 (1980)]. The possibility of frequency conversion of the argon excimer laser radiation to other wavelengths by a stimulated Raman scattering process is discussed.

Fundamental characteristics of a GaAs Schottky barrier diode mixer have been measured for the purpose of using it as the detector of a twin 118.8 µm CH3OH laser interferometer. The mixer sensitivity for beat oscillations of the twin lasers was measured in a frequency region from 1 MHz to 7 MHz. A signal to noise ratio of I.F. signal over 45 dB is obtained for the frequency up to 6 MHz. The dependence of the mixer sensitivity on local beam power was also measured. The I.F. signal level is approximately proportional to the local beam power in power level from 0.1 mW to 1.2 mW.

The ion temperature profile and the density distribution for the beam penetration in the plasma have been measured and evaluated using emissions produced by the charge exchange reaction between a heating neutral hydrogen beam and fully ionized impurities on the JIPP T-IIU tokamak. A 1 m spectrometer with a multichannel detector is used to detect ultraviolet and visible emissions from this reaction. The ion temperature profile during neutral beam heating (or plus ion cyclotron range of frequency heating) is obtained from the Doppler broadening of emission spectra. The central ion temperature agrees with those from other diagnostics. The beam density profile is also in good agreement with the simulational result. The availabilities are demonstrated on this technique to measure the ion temperature and the beam density profile which are necessary to discuss beam heating efficiency and thermal transport.

For the measurement of the profile of a spectral line, a high dispersive monochromator with an Echelle grating and 12 channels of photoelectric devices using thin glass sheets to separate the line profile was constructed. The measured resolving power is about 2×105 and the linear dispersion at the image plane is 1.2 mm/Å at 5000Å. This instrument was used to measure the ion temperature of a BSG device by employing the 4686Å line of He II.

Electron temperatures as well as plasma densities of a transient plasma can be visualized directly on the pattern of a cathode-ray tube. The principle is based on Langmuir's single probe method. Electron temperature is obtained by differentiating a logarithm of the probe current with respect to the probe potential. Then, if the probe potential is changed linearly with time, electron temperature is given by the ratio of probe current to its time derivative. (L.T.W.)

N-type indium antimonide shows the photoconductive effect not only in the far infrared, but also in the millimeter-wave region. Millimeter-wave photoconductivity was observed in the 2 mm-wave region to clarify the origin of the effect. It is concluded that, in elements with low carrier concentration, the impurity transition between shallow donor levels is the main process for the photoconductivity, while the hot electron photoconductive effect is small as compared with the impurity photoconductivity. Performances as a millimeter-wave detector are also studied. Signal-to-noise ratio of InSb detector is superior to that of conventional silicon point contact diode. Rise and decay times of the detector without magnetic field are about 0.4 µs and 0.7 µs respectively. This detector is useful even for measurements of incoherent radiation.