J. Oberling, P. King, E. Merilh

Today we swapped Diode Box 1 (DB1) for the PSL HPO with a spare shipped up from LLO.  The swap was relatively painless, although we did have a delay in attempting to extract a rounded screw from the lid of the "new" diode box.  Once that was taken care of the DB was installed in the PSL LDR.  We then turned only DB1 on with 20A of current.  Using an IR camera we confirmed that none of the fiber connections were overheating (all were <23 °C).  The PSL was then restarted.

For the new DB, we used an operating current of 49.3 A and set the temperature setpoints for the individual diodes to 29 °C.  The HPO came up with zero issues.  We then rotated each fiber connecter in the DB to maximize the power output by the HPO (unscrew the connector just enough so the fiber can rotate, rotate to maximize power, re-tighten connector).  Once this was done DB1 was closed and we slid it into place in the rack.  The 35W FE was restarted and injection locking engaged; the PSL was left to warm up in this configuration for ~1 hour.

After the warm-up period, the pump diode operating current and temperatures were adjusted to incorporate the new DB.  The temperatures of the diodes in DB2, DB3, & DB4 were unchanged; the temperatures of the diodes in DB1 were changed to 28 °C.  The operating current of each of the 4 DBs is summarized below (a screenshot is attached for future reference):

• DB1: 48.6 A
• DB2: 51.5 A
• DB3: 51.5 A
• DB4: 51.5 A

The PSL is now outputting ~158 W, and the PMC is transmitting ~60 W.  The PSL is now fully recovered from the DB swap and functioning as it was before work began.  The SN of the old DB is OBS2-DB1, the SN of the new DB is OBS1-DB1.

This closes LHO WP 7019.  Incidentally, this work also completes FAMIS 3653 (Weekly PSL Power Watchdog Reset) and FAMIS 8425 (PSL Weekly HPO Pump Diode Current Adjust).