PeterK, JeffB, RickS

This morning, Peter set irises to mark the beam pointing in advance of the water line work.

We then installed stops to register the position of the Front End baseplate, removed the pump fibers, moved the Front End box to the edge of the table,  removed the 35-W amplifier from the Front End box, and replaced the "quick connect" water fittings with 8 mm push-to-connect tubing fittings (see attached photos).

We did a pressure test with the 35-W head plumbed in the new configuration but outside the Front End box to check for leaks before re-installing it and moving the Front End box back into location.

We also removed all the flow-regulating valves from the supply-side water manifold for the three circuits: 35-W amp, 70-W amp, and high-power shutter.  We moved the flow meters to the return-side manifold so that they would respond to a leak in the water path by shutting down the chiller before exhausting the water supply.

Initial flows were: 1.3 lpm, 2.7 lpm, and 1.4 lpm for the three paths.  We then installed a 3-4 ft. section of 6 mm (OD) tubing in the 70-W amp path.  The resulting flows were: 1.4, 1.9, and 1.4 lpm.  So we added about 40 ft of 8 mm tubing (we didn't have any more 6 mm tubing) to get flows close to the 1.5 lpm target: 1.4 lpm, 1.6 lpm, 1.5 lpm (see attached photo).  Note that the "pwrmtr" signal is really for the HP shutter).

Note that we have not yet modified the chiller configuration to reduce the laser-end water pressures, now about 70 psi on the supply side and 50 psi on the return side, by throttling the chiller output to reduce the pressure drop across the heat exchanger on the return-side path to the reservoir.  We plan to do that later in the week.  We are waiting on a part that is schedule to arrive today or tomorrow.

Our detailed task list is also attached for future reference.