The laser temperature instability continued also after replacing the WI CO2 main laser with the spare one  (fig.1).

Thus, yesterday afternoon EGO crew swapped the WI CO2 chiller spare with the BACK UP one that seemed to work well in the previous tests.

With this new configuration, the chiller kept the laser temperature stable for all night (fig.2).

The current guardian system configuration is:

-the WI CO2 chiller is the old back up one

-the back up chiller is the initial chiller spare whose cooling capacity is limited. 

All chillers are settled on the ‘medium’ flux.

Thus, on 4 total chillers, two chillers do not work properly and need to be repaired.