Abstract
Wiggler and undulator magnets can provide very intense photon flux densities to beam line components. This paper addresses some thermal/materials consequences due to such impingement. The LBL/Exxon/SSRL hybrid-wiggler beam line VI [1] now nearing operation will be able to provide up to ∼ 7 kW of total photon power at planned SPEAR operating conditions. The first masks are located at 6.5 m from the source and may receive a peak power density (transverse to the beam) exceeding 20 kW/cm 2. Significantly, this heat transfer rate exceeds that radiated from the sun's surface (7 kW/cm 2) and is comparable to that if welding torches. Clearly, cooling and configuration are of critical importance. Configurations for the first mask, the movable mask and the pivot mask on this beam line are presented together with considerations of thermal stress fatigue and of heat transfer by conduction to water-cooling circuits. Some preliminary information on the heating of crystals and mirrors is also presented. For the future, many additional intense wiggler/undulator beam lines are contemplated at several storage rings. The design of these beamlines would be enhanced by faster and more accurate computational techniques. LBL is developing a computer code which will be capable of giving photon power densities onto impinged surfaces for a wide range of source and beam line parameters. These include electron beam energy, current, emittance and orbit deviations; wiggler/undulator length, period and magnetic field; photon energy and angular distribution; reflection/absorption at intermediate impinged surfaces; defining apertures and focusing by mirrors. Three-dimensional computer programs for temperature, stress and strain have been available for some years, but “user friendly” versions are being sought. Other items to pursue are also suggested.
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