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AOS (Baffles & Beam dumps)
tomotada.akutsu - 22:05 Monday 29 January 2018 (4042) Print this report
[WAB cooling] Replacing damping magnets

Simon, Miyo, Hasegawa, Akutsu:

Set back the WAB suspension from the saving mode position to the nominal position in the chamber (Fig 1). During the moving, we found the teflon sheet undermeath the WAB suspension made some dusts probably due to the friction of the WAB moving...  (Fig 2). how can we avoid this kind of dust??

Detached two damping suspensions which had neodymium magnets for passive damping (Fig 3, 4). Here we firstly had attached neodymium magnets in Mitaka, as we only had had those. Today we have SmCo magnets, so they were replaced. SmCo's magnetism won't change so much in the cryogenic temperature, comparing with that of neodymium, so the SmCo will be used for the actual WAB suspension. Another demerit is that the SmCo's magnetism is about twice weaker than that of neodymium. So we attached eight SmCo magnets to the damping plate (Fig 5, 6), where four neodymium were attached. As usual, the magnet's directions were alternated (Fig 9).

The magnet dampers were attached to the WAB suspension in the cryostat (Fig 7). Then protectors for the suspension were detached (Fig 8, 10), and so the WAB would be suspended. This is the first time a baffle in KAGRA was suspended! We vibrate the WAB breifly to check the magnetic damping, and seemd so so so far.

Details here.

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