Spring 1998: Progress Report

January
Mid of January the heating of the eastern tube started, but the phase cutting current control only survived the first half hour. The thyristors were underrated. Preparation is being made for leak testing the second arm.

February
The blown-up thyristors have been replaced by appropriate ones and the phase cutter works again. The eastern tube has been air baked at 200°C for about one and a half day. The vacuum bake lasted for three days. The mass 2 (hydrogen) readings of the quad in the central station showed too high values. In addition, as the quad was not baked simultaneously with the rest of the tube a lot of dirt accumulated in the quad. Another air bake and a subsequent vacuum bake (in combination with changing the gauges for clean ones) solved this problem. After switching off the heating of the tube, two leaks developed at the 600 mm COF flanges between the tube and the 600 mm gate valves. Tightening the bolts solved this problem.

March
The pressure in the eastern tube is now (27.3.98) 2•10-8 mbar and the quad reading shows a clear air signature. We hope it is one of the flanges in the trench and not the tube itself. As this pressure is clearly higher than the nitrogen partial pressure was before the bake, it is a new leak we are facing.

The northern tube is pumped down and has reached a pressure in the 10-5 mbar range. Leak testing is under way. The stacks for the Mode Cleaners are well on their way.

Angela Di Virgilio from Pisa came by to visit GEO600. Here she takes a look at the assembly shop. (From l.t.r.: Karsten, Angela, Aniello, Benno, Mike.) Zoom Image
Angela Di Virgilio from Pisa came by to visit GEO600. Here she takes a look at the assembly shop. (From l.t.r.: Karsten, Angela, Aniello, Benno, Mike.) [less]
Benno and Kasem look how to fix the roundtables to the TCMa top plate lying on it's back. The top "plate" has evolved from a planar to a rather Escher-like structure. Zoom Image
Benno and Kasem look how to fix the roundtables to the TCMa top plate lying on it's back. The top "plate" has evolved from a planar to a rather Escher-like structure. [less]
Peter and Jochen look at the top plate hovering above the stacks. Zoom Image
Peter and Jochen look at the top plate hovering above the stacks.
Kasem and Benno put the top plate onto the stacks. Zoom Image
Kasem and Benno put the top plate onto the stacks.
Mike adjusts the fit of the top plate. Zoom Image
Mike adjusts the fit of the top plate.
This view shows the stacks mounted on the resp. holder plates. The large thick thread-poles hold the upper part of the tank after opening it. The small ones bear square plates for the lowering device. Zoom Image
This view shows the stacks mounted on the resp. holder plates. The large thick thread-poles hold the upper part of the tank after opening it. The small ones bear square plates for the lowering device. [less]
The lowering device consists of three beams and a round plate. The beams are fixed to the square plates. Zoom Image
The lowering device consists of three beams and a round plate. The beams are fixed to the square plates.
Here the top plate is bolted to the lowering device. The stage is lowered by turning the nuts holding the square plates. (From l.t.r.: Mike, Benno, Calum, Peter.) Zoom Image
Here the top plate is bolted to the lowering device. The stage is lowered by turning the nuts holding the square plates. (From l.t.r.: Mike, Benno, Calum, Peter.) [less]
The top plate sits upon the stacks. Now the lowering device can be removed. Zoom Image
The top plate sits upon the stacks. Now the lowering device can be removed.
The top plates are made from box-section stainless steel elements. There are nozzles in each layer in order to allow damping material to be filled in. Here Mike and Calum apply fluid graphite-doped RTV to the top plates. A rather messy affair! Zoom Image
The top plates are made from box-section stainless steel elements. There are nozzles in each layer in order to allow damping material to be filled in. Here Mike and Calum apply fluid graphite-doped RTV to the top plates. A rather messy affair! [less]
By contrast the wiring of the control devices is a very delicate affair. The top plate has been inserted into the tank. From the intermediate round table the coil holder goes down. Below one can see a dummy mirror. Calum and Benno fix the wires of the coils. Zoom Image
By contrast the wiring of the control devices is a very delicate affair. The top plate has been inserted into the tank. From the intermediate round table the coil holder goes down. Below one can see a dummy mirror. Calum and Benno fix the wires of the coils. [less]
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Dr. Christian Ahrens, Head of Projects all over the World, National; Prof. Dr. Herbert Walther, Head of the Max-Planck-Society for Quantumoptics (MPQ) and Prof. Dr. Karsten Danzmann, Head of the Intitute for Atomic and Molecular Physics, Dept. of Spectroscopy, with the Registration Documents; Dr. Bernd Lüdecke, Head of Projects all over the World, National. Zoom Image
Dr. Christian Ahrens, Head of Projects all over the World, National; Prof. Dr. Herbert Walther, Head of the Max-Planck-Society for Quantumoptics (MPQ) and Prof. Dr. Karsten Danzmann, Head of the Intitute for Atomic and Molecular Physics, Dept. of Spectroscopy, with the Registration Documents; Dr. Bernd Lüdecke, Head of Projects all over the World, National. [less]
Dr. Ahrens, Prof. Danzmann, and Prof. Walther in front of the GEO600 posters. Zoom Image
Dr. Ahrens, Prof. Danzmann, and Prof. Walther in front of the GEO600 posters.
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