To: Distribution 17 September 97

From: Martin Nordby

Subject: IR Engineering and Physics Meeting Minutes: 29 August 97

Eddie Lin presented results of further RF analysis of the B1 Ion Pump screen impedance. He modelled one 3 mm diameter hole in a round beampipe, then scaled the result for the 1690 holes in the final design. Total inductance is 0.04 nH, which is 0.1% of the total budget of 83 nH for the rings. Total power lost due to this inductance is 0.52 W per 3A beam.

Total power lost due to all sources is: 0.5 W (inductive) + 7.5 W (resistive/HOM on st. steel) + 11.3 W (resistive/HOM on Cu) = 20 W. This is for two 3 Amp beams. For the nominal running condition of 1A HEB on 2A LEB, total power is 5/18 of this, or 5 Watts.

Mike Sullivan estimated that radiation scattering off the main S.R. strike regions nearby could add another 20-30 Watts, to bring the total to 50 Watts. This will be used for subsequent thermal analysis.

Karen Fant presented the final design for the pump screen. It has angled holes, backed up by one rank of baffles. This yields a net pumping speed on beamline of 300 L/s for the ion pump, while eliminating all direct lines-of-sight from the beampipe into the pump volume. The baffles are brazed to the beampipe screen to thermally sink them, and hold them in place. The holes in the screen will be pointed away from the IP to avoid heating the baffles from scattered SR from the B1 mask strike.

Scott Debarger reported on plans to support the Q2 Magnet in the Raft. The earlier plans to use rod ends did not pan out, since the supports did not fit through the Raft. Also, the supports must allow the magnet to slide in X (transversely) towards the HEB during installation and removal. This disentangles the magnet water manifold from the cutout in the Raft.

The final support design for the magnet is a push-me/pull-you style support, similar to that being used for the Q1 Magnet. There are 3 Y-supports, and 2 X-supports, with the Z-position set when the support brackets are bolted and pinned to the magnet during installation. All adjustment is made from the outside, through access holes in the Raft, except the out-board Y-support, which can be reached from the end of Q2. This ensures that the magnet can be aligned with the Raft cover mounted, and with SK1 in position.

Range of motion for the supports is +/- 0.5" in Y, 0.7" in X towards the LEB, and 1.45" in X towards the HEB (for magnet removal). The supports clear all bussing and water connections for the magnet, which happen mostly above/below the magnet core, and at the very out-board end of the magnet. The magnet sits on 3 ball-ended bolts, so its should not bind up during alignment

These minutes, and agenda for future meetings, are available on the Web at: