[en] Low photo desorption (PSD) from surfaces of vacuum chambers increases the beam lifetime and reduces the cost of the pumping system of any storage ring. In compact rings where all radiated power (∼10 kW) is incident on a few meters only, low PSD and good thermal conductivity of photon absorbers are of particular importance. An experimental chamber in which one meter long bars can be exposed to white photon beam with 500 eV critical energy has been built and installed on the U10B beamline in the VUV ring at the NSLS. Several reference bars made of high purity copper and a TiN coating on copper have been measured. Subsequent runs will include gold coating on copper, aluminum (200 degree C baked), diamond coating on copper and uncoated beryllium bars. In this paper the desorption coefficients will be measured and compared. 6 refs., 4 figs

No abstract available

No abstract available

[en] Low photo desorption (PSD) from surfaces of vacuum chambers increases the beam lifetime and reduces the cost of the pumping system of any storage ring. In compact rings where all radiated power (∼10 kW) is incident on a few meters only, low PSD and good thermal conductivity of photon absorbers are of particular importance. An experimental chamber in which one meter long bars can be exposed to white photon beam with 500 eV critical energy has been built and installed on the U10B beamline in the VUV ring at the NSLS. Several reference bars made of high purity copper and a TiN coating on copper have been measured. Subsequent runs will include gold coating on copper, aluminum (200 degree C baked), hard carbon coating on copper and uncoated beryllium bars. In this paper the desorption coefficients will be measured and compared

[en] ENEL's long-lasting commitment in rationalizing the energy end-uses, has lead to the assessment of the potential for the substitution, in the field of thermal uses, of traditional processes with efficient electro-technologies. The evaluation has been performed by taking in account the advantages for the user, in terms of the reduction in operating costs (energy included), for the electricity industry (increase in kWh sales), and for the Society (savings in primary energy consumption). The analysis allowed to identify many applications for which the primary energy saving is jointly obtained with significant extra-energy advantages for the end user. In order to validate the effectiveness of innovative electro-technologies, a demonstration activity, by means of pilot plants, is in progress. (author)

[en] Ever increasing circulating currents in electron-positron colliders and light sources demand lower and lower photodesorption (PSD) from the surfaces of their vacuum chambers and their photon absorbers. This is particularly important in compact electron storage rings and B meson factories where photon power of several kW cm^-1 is deposited on the surfaces. Given the above factors we have measured PSD from 1 m long bars of (a) solid copper and solid beryllium, and (b), TiN, Au, and C thin films deposited on solid copper bars. Each sample was exposed to about 10²³ photons/m with a critical energy of 500 eV at the vacuum ultraviolet ring of the National Synchrotron Light Source. PSD was recorded for two conditions: after a 200 degree C bakeout and after an Ar glow discharge cleaning. In addition, we also measured reflected photons, photoelectrons, and desorption as functions of normal, 75, 100, and 125 mrad incident photons

[en] Experiments on spherical heating of fusion targets in the Del'fin-1 device reveal laser scattering at frequencies of ω₀ and 2ω₀ by a plasma region with a density well below the critical density. For each of the frequencies, the size of the emission region is roughly four times the initial target diameter, and the region has a sharp boundary. Some possible explanations for the observations are proposed

[en] We demonstrate that the mode dispersion of gas-filled waveguides can be used to match group velocities of guided laser pulses. The synchronism is attained by balancing normal dispersion of the gas with geometry-dependent negative waveguide dispersion. By applying this approach to the process of Raman sideband generation in an impulsively excited SF₆, a multifold increase in the scattering efficiency was achieved, with the number of generated phase-locked Raman components sufficient to approach the attosecond regime of optical-field synthesis

[en] PEP-II will be a meson factory circulating asymmetric beams of 9 GeV and 3.1 GeV having maximum currents of 3.0 A. Copper beam chambers and absorbers will intercept resulting synchrotron radiation and it is critical that the dynamic gas load from photo stimulated desorption (PSD) and thermal outgassing is below 2x10^-6 molecules per photon. An experiment was set up to measure PSD from 1 m long bar samples and a chamber sample, fabricated from selected copper and copper alloys, then exposed to white light with a critical energy of 500 eV, on beamline U10B at the VUV ring of the National Synchrotron Light Source (NSLS). Based on U10B results a prototype chamber was built and will be exposed to white light with higher critical energies of up to 5 keV, on beamline X-28A at the X-ray ring of the NSLS. This paper presents the measurements of H₂, CO, CO₂ and CH₄ desorption yields as function of accumulated photon flux, angle of incidence, sample material, and surface condition. The results are compared with that of previous work on similar materials and with that of others for copper. (author)

[en] In support of PEP-II, a high luminosity B factory, photo-desorption of Cu alloys were measured to demonstrate suitability for ultra-high performance under high radiation loads. Results show that η_eff≤2x10^-6 mol/photon is a practical design value for Cu vacuum chambers. Commissioning times to attain this value in B factories can be expected to be <50 h. Pre-cleaning with Ar glow discharge was shown to be effective