> From: Ernie Ihloff > Sent: Wednesday, December 5, 2018 2:36:50 PM > To: Ruben Fair; Probir Ghoshal; Robin Wines; David Kashy; Sandesh Gopinath; Javier Gomez > Cc: Krishna Kumar; Juliette Mammei; Kelsey, Jim; Jason Bessuille; Karen Dow; Bolek Wyslouch; Richard Milner; Mark Pitt > Subject: Moller Prototype coil Power/flow test - quick summary > > Hi Jlab people, > We have recently done testing on the prototype coil at MIT Bates. Summary is we had no surprises during the testing and I am very happy at this point. The original design is pretty sound. > 1. Water flows at 100, 150, 200, 265/275 psi were done on all circuits. They were very close to my original design values with some being more flow and it the worst case 20% lower than design. > 2. We full power tested the two sets of coils with the worst case delta T. The end sets of the coil that I called A-A and D-D. We got lower than design delta T on both sets (due to convection coiling in the room) but it was absolutely uneventful. > 3. The DarkLight supply performed perfectly for this test so thanks to Richard Milner for letting me use it. Stable and very well matched to load. Alpha should be on any magnet power supply bidders list. I paid 125 K a few years ago for 5 ppm, 2200 amp, 90V supply. There are other excellent vendors for the four supplies needed. > 4. The only issue at all is the Chiller we used owned by ProTom, had an issue with the second compressor not coming on so during a long test (more than one hour), the inlet water cooling temp rose 5C during the test. > 5. Worst case delta T was about 30 Cin either coil . Water was not flowing or present in coils not powered. Thermal images were very useful but showed the leads not getting hot and the rest of coil doing as expected. > We (at MIT) have have looked at the idea of running the four coils in series at some other value then the design value (since we have a single supply). My strong recommendation to forget this test. It will be hard to make high current jumpers safely and the test is of dubious value. We have learned a lot from FLIR images of the coils at this point that make me less worried about stress in coils due to delta T. Cross cooling may be a factor but it would just lower the delta T in the worst coils we already tested. > Summary from my viewpoint: > 1. the present current density of about 20 A/mm^2 do not present any issue other than a water flow design parameter. Get the water needed through the coil and delta T is correct. > 2. The velocity of about 15 ft/sec or 5 meter/sec does not seem like any issue at all. MIT would like to be involved in the design of the water cooling system for Moller. > 3. The pressure of 275 psi used in the test coil was zero issue and could be higher if needed (I would say 350 psi or so). It was easy to achieve and not a problem at all. > 4. At this point, I am complete with the tests I am planning to do. > 5. If alternate designs have lower power usage, current design or pressure drop, that is fine but at this point, the Prototype coil was a success and we learned a lot of valuable information and hopefully will be able to silence critics. I would expect this magnet coil to work for years at these values if the inlet water is about 20C. > 6. Now the next step on the coil design is a time consuming CAD problem to fit it in coils , get connections in without interference to the Moller envelop. > Thanks, Ernie > -- > Ernie Ihloff P.E. > Principal Research Engineer > Engineering Group Leader > MIT Bates Research and Engineering Lab > Office 617-253-9503 > Cell 781-760-9381 > eihloff@mit.edu