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- H. R. Kremers, J. P.M. Beijers, S. Brandenburg
KVI, Groningen
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We present the design, construction and the first results of a new, versatile emittancemeter and profilemonitor for low-energy, multiply-charged ion beams. Both instruments share the same basic design, e.g. they fit on the same size vacuum flange and many parts can be exchanged. The central component of both instruments is a beam-imaging device, consisting of two multi-channel plates (MCP) in the chevron configuration followed by a phosphor screen. This combination transforms the two-dimensional beam-intensity distribution to a two-dimensional light-intensity distribution, which is imaged via a mirror and a lens system onto a CCD camera mounted outside the vacuum. The MCP, phosphor screen and mirror are mounted on a table which can be moved in and out of the beam. For emittance measurements the device is equipped with a pepperpot plate with a pattern of small holes in one direction, which is stepped through the beam in the orthogonal direction. The structure of the pattern can be adapted to the expected shape of the emittance. By taking images of the beamlets passing through the holes at a number of positions the full four-dimensional beam emittance can be reconstructed.
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