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Title. Beam clipping Problems in GEO 600 ??. Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut). Stefan Hild Ilias WG1 meeting, June 2005. Introduction. After installation of new Power Recycling mirror less light power was observed than expected:
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Title Beam clipping Problems in GEO 600 ?? Max-Planck-Institut für Gravitationsphysik(Albert-Einstein-Institut) Stefan Hild Ilias WG1 meeting, June 2005
Introduction • After installation of new Power Recycling mirror less light power was observed than expected: • Hypothesis: Mode matching into PR cavity is not too bad (?) • Hypothesis: beam is clipping somewhere inside the cavity • Expected (simulations) 4.5 kW • Measured 1.5 kW
Simple model cavity Simple model: 2 mirror cavity, 1.7 W incident, T1 = 900ppm, T2 represents losses expected reality Intracavity power [W] reflected power [W] Losses in cavity overcoupled undercoupled Looking for intracavity losses of the order of 500 ppm
Power Recycling reaction mass CCD Clearly much light on the reaktion mass, but at least beam seems to be centered (in respect to the reaction mass) Main beam CCD
Potential clipping spots in TCC north arm MPR east arm dark port
Power Recycled Michelson Used HeNe-Laser from endstadions to project the free aperture onto MPR reaction mass. Result: no clipping inside the power recycling cavity
Signal Recycling cavity We definitely see clipping between beamsplitter and MSR (see blue line) Side note: there is also clipping on MSR reaction mass. HeNe from far end locked DRMI
Smoking gun: BDBSs1 CCD Suspect the beam to clip the beam dump (blue arrows)