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[en] A Penning trap which is optimized for transverse resistive cooling yields a cooling time constant for trapped He+ ions of as low as 3 seconds, depending on cooling duty cycle. Opposite quadrants of the ring electrode resonate (Q=1800 at 7.4 MHz) with Nb/Ti inductors at 4.2 K. The f' motion is resonantly cooled by operation at 2 Tesla axial field and trap voltages from 12 to 38 Volts. Ion signals are magnetically coupled to a 4 K GaAs fet preamplifier, wide-band 300 K amplifier and linear diode detection system. The rate of cooling is set by fractional time on resonance during sweep of the trap voltage. Shifting and broadening due to space charge are demonstrated. Other interesting features of the ion spectra, such as peak structure, response to heating by f+ - f-, and growth/decay of the peak components, will be presented
[en] The results reported give evidence of a high energy desorption peak which exhibits a rapid growth when the quantity of helium, trapped in the tungsten at energies higher than 400eV, is increased. The presence of this peak can be explained by the migration of vacancies containing helium atoms, leading to the formation of microbubbles of gas in the metal
[fr]Les resultats presentes montrent l'existence d'un pic de desorption fortement energetique dont l'importance croit avec la dose d'helium fixee par le tungstene soumis a un bombardement d'energie superieure a 400eV. La presence de ce pic peut s'expliquer par la migration d'atomes d'helium situes en position lacunaires conduisant a la formation de microbulles de gaz incluses dans le metal
[en] The method of complex-coordinate rotation is used to investigate resonances in e+-He+ scattering. By using Hylleraas-type wave functions the auhor has obtained resonance positions and widths for two S- and two P-wave resonances. The resonance positions for the two S-wave states are consistent with those obtained by Bhatia and Drachman who used the stabilisation method. The total widths for the lowest S- and P-wave resonances are determined in the present work as 3.52 eV and 4.83 eV, respectively, raising the possibility that such resonances may be detectable in e+ - He+ scattering experiments
[en] Complete text of publication follows. Plasmaspheric drainage plumes are regions of cold dense plasma that connect to the main body of the plasmasphere and extend to the outer magnetosphere. Plumes form in response to sudden changes in magnetospheric convection and are associated with the drainage of plasmaspheric plasma into the outer magnetosphere. In this study we used two different techniques to study ion densities in plumes. The first technique involves the extreme ultraviolet (EUV) camera onboard the IMAGE satellite. This instrument detects solar 30.4 nm radiation that is resonantly scattered by He+ ions and produces images every 10 min. The images from near apogee (∼8 Re) can provide global perspectives of the plasmasphere with 0.1 Re spatial resolution. The second technique involves measurements of magnetospheric field line resonances. Cross-phase analysis from closely spaced ground magnetometers yields the eigenfrequency of magnetic field lines, providing information on the plasma mass density near the equatorial plane. Data from an extended meridional array of ground magnetometers therefore allows the radial density distribution to be remotely monitored. We studied an event during the interval from 9 to 12 June 2001. The EUV images show the presence of two plumes on 10 June, with the western edge of the one of them rotating with ∼60 % of the corotation velocity. The field line resonance measurements were used to produce time series of the plasma mass density at L = 3.6 - 4.1 in the European meridian, which indicated significant enhancements in density when the field line projections caught-up to the western edge of the plume. This is clear evidence of the simultaneous detection of plumes by both the EUV and field line resonance measurements techniques. This presentation will show details of plasma density and composition in the plumes.