An experimental and theoretical investigation of lifetimes of metastable levels in La II has been performed. The experimentally obtained results using the laser probing of a stored ion beam were tau=5.2+/-0.2 s for the a(1)G(4) and tau=2.1+/-0.3 s for the b(1)D(2) levels. Within the error bars, the results are in good agreement with the relativistic Hartree-Fock calculations including core polarization.

The ECR source now delivers beams to experiments. The EBIS source, CRYSIS, has been used with some radioactive species such as tritium, and uranium. The research groups studying molecules and molecular clusters often request ions that can only be produced in small amounts. Thus, weak beams, less than 1 nA from the ion source, have been successfully injected into the ring and stored. Furthermore fast ramping of the magnets during acceleration is reported. 1 OVERVIEW CRYRING is a 52-m circumference ion storage ring. Bρ max is 1.44 Tm, giving a maximum energy of 96q 2 /A 2 MeV/u. q and A are ion charge and mass. The injection energy is 300 keV/A if q/A>0.23 so the ions can be accelerated in the RFQ, otherwise 40 keV total energy. 109 different ions have been stored in the ring, 30 different ones the last year. An EBIS ion source produces highly charged ions up to i.e. Pb 60+ . It is used both for injection in the ring and for low energy experiments. A recent addition is an ECR source for medium charged ions, which presently only is used for low energy experiments. The beamline to the ring will soon be finished.

Sputter deposition using a focused ion beam has been investigated as an alternative to magnetron sputtering for the deposition of thin-film gold electrodes onto quartz resonators. One potential concern is the inclusion of argon in the growing film when argon ions are used for sputtering. Argon retention in sputter-deposited gold films using an 11.5 keV argon ion beam was investigated with Rutherford backscattering spectrometry and it was found that in layers deposited at close to normal ejection angles the argon trapping was at the level of less than or equal to 1 at,%, similar to magnetron-deposited layers, whereas argon incorporation increased with the ejection angle up to several per cent at large angles. Copyright (C) 2000 John Wiley & Sons, Ltd.

New edge profile measurements, including calorimetric measurements of the parallel heat flux, were made in Extrap T2. Test limiters of pure molybdenum and the TZM molybdenum alloy have been exposed in the edge plasma. The surface damage was studied, mainly by microscopy. Tungsten coated graphite probes were also exposed, and the surfaces were studied by microscopy, ion beam analysis and XPS. In this case cracking and mixing of carbon and tungsten at the interface was observed in the most heated areas, whereas carbide formation at the surface was seen in less heated areas. In these tests pure Mo generally fared better than TZM, and thin and cleaner coatings fared better than thicker and less clean.

A new compact magnetron plasma system and its characteristics are described. The system makes it possible to carry out ion irradiation experiments at high fluxes of 1018 ions/cm2·s and to reach fluences of 1022 cm−2, with a homogeneous distribution over an area of 0.3 × 0.2 cm2. The sample temperature, the distribution of ion flux densities within the sputtering zone, and the energy spectrum of ions are in situ measured during irradiation. The device is capable of producing a discharge current of up to 1.2 A and mean current densities of up to 100 mA/cm2. The mean ion energy can be regulated in the range 50–500 eV by changing the working pressure and the discharge self-sustaining degree. The plasma can be swept over the interaction zone by using a moving magnet controlled by a stepping motor. The VC characteristics and discharge current relations were measured for several different gases and at different pressures in the plasma. Integral ion energy and current density distributions at the cathode surface were measured at different parameters. In the first experiments targets of graphite, silicon, molybdenum and titanium were used and exposed under similar plasma conditions using deuterium in the discharge, energies of 150 eV and fluences of 1021 cm−2. RBS (Rutherford backscattering spectrometry) and NRA (Nuclear reaction analysis) were analytical techniques for the determination of deposited layers with respect to the quantity of deposits and for the study of the purity and homogeneity of the irradiated layers.

A new compact plasma simulator device has been mounted on line at the Van de Graaff accelerator and successfully used for deposition experiments of deuterium atoms with the mean ion energy of 120–140 eV. Deuterium retention in graphite exposed to a magnetron plasma at flux densities above 1017 D cm−2 s−1 has been studied by nuclear reaction analysis. A dynamic retention of about 1 × 1016 D/cm2 has been identified in the discharge with a current density exceeding 16 mA/cm2. This dynamic inventory is released within 60 ms after the discharge has been stopped. The interpretation is based on trapping, detrapping and diffusion of deuterium in graphite.

Mass spectra of negative secondary ions emitted from the surface of a stoichiometrical superconducting YBa2Cu3O7-x ceramic bombarded by 250 eV positive argon and oxygen ions were measured. The results show that the reduction of the primary ion energy reduces the yield of heavy secondary ions. It was observed that the supply of oxygen to the sample bombarded by Ar+ ions enhances the yield of secondary negative ions, although this yield is further enhanced by switching to positive oxygen primary ions. Moreover, the bombardment of a YBCO ceramic sample by oxygen ions is characterized by a particular enhancement of the yield of barium and barium-containing molecular ions.

This paper reports the results of scanning tunneling (STM) and atomic force microscopy (AFM) studies of D+ irradiated graphite and graphite-silicon mixtures. The microscopes were used for studying surface topography and for measuring the surface roughness. The substrates were exposed at various temperatures (60 and 700°C) to different doses of deuterium ions in simulators of plasma - surface interactions and in the TEXTOR tokamak. Also nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy were applied for the qualitative and quantitative determination of surface composition. The initial stages of radiation damage, nanometer-sized bubbles/blisters, were found in plasma-eroded surfaces. These structures only appeared in the graphite phase on the multicomponent material. The microroughness of the surfaces was measured. We also used the AFM for probing the thickness of the plasma-modified layers. The results correlate with the presence of deuterium measured by NRA depth-profiling. Moreover, the AFM reveals the co-deposited layers formed on surfaces facing the tokamak plasma. The appearance of these layers is clearly correlated to the amount of co-deposited atoms.

Mesoporous chromia aerogels with a surface area of 484-735 m2g-1 a pore volume of 0.4- 0.9 cm3 g-1 and a pore diameter of 3-9 nm were prepared by urea-assisted homogeneous precipitation from an aqueous Cr(NC3)3 solution, followed by continuous supercritical CO2 extraction. The aerogels were characterized by means of N2-adsorption isotherms, AA, HR- TEM, FTIR, thermoanalytical methods TPD, TPO, DSC and X-ray diffraction in combination with structure modeling. For production of mesoporous aerogels with surface areas > 700 m2g-1was required Pco2 of ≈ 400 bar. The chromia aerogels consisted of 3 to 5 nm nanoparticles representing a monoclinic analogue of α-CrOOH in which half the O atoms and OH groups were replaced with coordinately bonded water molecules. After dehydration at 550-600 K the materials retained their texture, being converted to two-dimensional fragments (clusters) of α -CrOOH crystals built on [Cr(OH)3O3] octahedra without bonding along the Z- axis (N2, vacuum) or to amorphous CrO2 (air). At temperatures of >650 K in air and of > 773 K in an inert atmosphere, the material was converted to a-Cr2O3 with 50-nm particles .

Sputtering yields at energies ranging from 0.5 to 8 keV have been determined for oxygen and neon sputtering of thin carbon films, deposited on metal substrates. In order to investigate the influence of chemical sputtering, the restgas composition was monitored with a quadrupole mass spectrometer, and the changes in the carbon layer thickness after sputtering were compared to the amount of sputtered carbon which had been collected on a surface situated in a backward direction. The small amount of carbon that was found on the collectors after sputtering with oxygen ions was taken to indicate that there is a significant contribution from chemical sputtering, even at room temperature. The residual carbon layers were investigated with SIMS after sputtering.