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Notes: The growth rate of a second liquid phase is studied in demixing process of n-butoxyethanol/water mixtures. Following the liquid/liquid coexistence curve from far-off critical compositions to the critical point, the growth rate of the droplets slows down markedly. The values of the mutual diffusion coefficient D extracted from the growth rate data are found to scale approximately with a power law of the form D ∼|| (T − Tc)/Tc||0.79.

Notes: We present beam measurements which have been carried out using a CHORDIS ion source supplied with a modified extraction system. This system is designed to handle extraction voltages up to 60 kV. For beam diagnostics, a Faraday cup and a sector magnet have been used. Presented are measurements on beam current, mass, and energy spectra in dependence on various source parameters as gas pressure, arc voltage, and extraction voltage.

Notes: In cooperation with the Lawrence Berkeley Laboratory, a multicusp ion source has been investigated. The goal of these investigations is to generate a nearly pure atomic nitrogen (N+) ion beam. To achieve this, the discharge chamber is divided into two parts of different plasma parameters by means of a filter magnetic field. As beam diagnostics, a bending magnet and a faraday cup have been used. Measurements of the beam current density and the ion composition for a wide range of discharge conditions have been performed. By using a Langmuir probe, we have performed measurements of electron temperature and electron density.

Notes: A duoplasmatron ion source fed with nitrogen usually produces a N+ fraction of approx. 60% in dc mode. In pulsed mode, the duoplasmatron ion source turns out to be a nearly perfect source for atomic nitrogen ions with a high fraction of more than 90% in the milliampere range. This is achieved by pulsing the arc discharge and not by use of any filter magnets. Parameters of operation will be given, such as the comparatively low gas inlet pressure and the arc current, which far exceeds the arc current in dc mode.

Notes: Neutron yield measurements are performed at the Jülich Tokamak experiment TEXTOR with different detectors located around the Tokamak and on center axis above the shielding roof. Due to the large structure of the machine and the extended diagnostic equipment, both virgin and scattered neutrons are detected. To prepare a Bonner sphere of appropriate response, the shape of the degraded neutron spectrum was determined with a spherical ionization chamber in situ. These investigations have been enlarged under quasi-real conditions at the accelerator facility of the Physikalisch-Technische Bundesanstalt in Braunschweig with a set of Bonner spheres used as a spectrometer. For the calibration the plasma neutron source is simulated by two point sources, 238Pu/B and 252Cf. The sources are moved around the TEXTOR vessel along the position of the magnetic axis.

Notes: Results of experiments, carried out in space and on earth, are reported in which spinodal decomposition in a single-component fluid (SF6) is studied by small angle light scattering. Deformed circular light-scattering patterns are observed. They reflect deformation of density fluctuations by gravity effects and shear flow.

Notes: Fundamental questions of electron beam ion sources (EBIS) are studied using three different setups. Cryogenic classical EBIS: The limit of ion–ion cooling in EBIS devices operating near the space-charge neutralization limit has been studied experimentally. To investigate different degrees of compensation of the electron beam by highly charged ions, a hemispherical analyzer has been constructed including a novel deceleration optic for high resolution. Using its energy definition we tested different modes of ion transportation in our multipassage magnetic spectrometer, which can be operated chromatically as well as extremely dispersively: up to 200 passages could be obtained. EBIS without magnetic field: First results on ion production in the short trap at the very dense crossover of an electron beam (XEBIS) confined only inertially without the use of magnetic fields are presented. Normal conducting short EBIS: Using a normal conducting field of 0.8 T of 25-cm length an EBIS is under construction to study extremely short ion extraction of approximately 4 μs for single turn injection into a medical synchrotron for cancer therapy (MEDEBIS).

Notes: Abstract: The time course of changes in the tissue impedance and the levels of extracellular transmitter and non-transmitter amino acids was studied in the striatum and hippocampus of the unanesthetized rat after cardiac arrest. Electrodes were implanted for the continuous measurement of tissue impedance so that a measure of the volume of extracellular space was provided. Alternatively, bilateral dialysis probes were used for monitoring levels of extracellular amino acids in subsequent 30-s samples using an automated precolumn derivatization technique for reversed-phase HPLC analysis and fluorimetric detection. The impedance started to rise ∼1.2 min following cardiac arrest, increased rapidly during the first 5 min, and increased almost linearly thereafter. After 15 min, a decrease of ∼50% in the extracellular space was calculated. The impedance rose more steeply in the striatum than in the hippocampus. The extracellular levels of taurine, which increased 〉300% within 5 min after cardiac arrest, most closely resembled the time course of the change in impedance. Glutamate and aspartate levels did not increase until 5 min after circulatory arrest, and at 15 min they had risen to a level of 465 and 265% for the striatum and 298 and 140% for the hippocampus of the resting release, respectively. The release of γ-aminobutyric acid (GABA) was multiphasic and did not resemble that of any of the other—putative—transmitter amino acids. Fifteen minutes after cardiac arrest, the levels of GABA were 617 and 774% of the resting release in the striatum and hippocampus, respectively. Glycine and ala-nine efflux substantially increased (232 and 151% in striatum and 141 and 154% in hippocampus, respectively) 15 min postmortem, whereas the glutamine level was slightly increased and levels of asparagine, histidine, threonine, ethanolamine, serine, arginine, and tyrosine were inconsistently higher in the two brain regions. At this time, the extracellular levels of glutamate, GABA, and aspartate were only slightly lower, as expected from the tissue levels and from levels of the other amino acids, an observation indicating that all the amino acids may diffuse through postmortem brain tissue to a nearly similar extent. This study provides evidence that extracellular levels of taurine reflect changes in distribution of electrolytes (and in membrane potentials), that the postmortem release of transmitter amino acids is multiphasic with a delay of at least 1 min, that postmortem shrinkage in extracellular volume cannot account for the increase in the content of transmitter amino acids in the dialysate, and that the massive overflow of glutamate, aspartate, GABA, and taurine seen during ischemia is the result of both release and the failure of uptake. Possible implications of the present findings for excitotoxic damage of the brain are discussed.

Notes: We present measurements on multichannel acceleration of intense, low-energy ion beams with a multiple electrostatic quadrupole array linear accelerator. The beam properties are investigated for different transverse and longitudinal focusing strengths, which can be adjusted independently in the accelerator. A maximum He+ ion current of four times 2 mA has been accelerated from 40 to 115 keV with an acceleration efficiency of 50%. Measurements and computer simulations suggest that the current is limited by transverse fields and by mismatch and misalignment of the beams, whereas longitudinal fields are of minor importance. The energy spread in the bunches is roughly three times the gap voltage.