Tonight we tested the longitudinal control of the SWEB bench while the ITF was in recombined mode. In order to check the performance of this loop to cancel microseismic noise, we excited the bench by injecting a line along Z at the top of the suspension.
The following data have been collected:
Line Frequency (Hz) | Line Amplitude | Loop status | Loop gain | Start time (utc) | Duration (s) |
0.1 | 600 | OPEN | 21:46:00 | 300 | |
0.1 | 600 | CLOSED | 10 | 21:51:30 | 840 |
0.1 | 400 | OPEN | 21:39:30 | 360 | |
0.1 | 400 | CLOSED | 10 | 22:06:20 | 240 |
0.1 | 400 | CLOSED | 50 | 22:15:30 | 180 |
0.1 | 400 | OPEN | 22:18:40 | 160 | |
0.1 | 300 | OPEN | 22:22:00 | 90 | |
0.1 | 300 | CLOSED | 50 | 22:24:20 | 140 |
0.1 | 200 | OPEN | 22:33:30 | 130 | |
0.1 | 200 | CLOSED | 50 | 22:36:36 | 180 |
0.2 | 300 | OPEN | 22:51:00 | 60 | |
0.2 | 300 | CLOSED | 50 | 22:52:00 | 100 |
0.3 | 300 | OPEN | 22:54:14 | 64 | |
0.3 | 300 | CLOSED | 50 | 22:55:34 | 116 |
The gain was set in line 408 of the SWEB_LC process. For a gain equal to 70 or above it was found that the loop became unstable (growing oscillations).
Data will be analyzed later.