Feb 11, 2011 Replacement Solenoid

Items for followup from previous meeting

1. Power supply. Current ~ 15KA, voltage 5-10 V. (Could existing power supply 3KA/10V be converted to 6KA/5V?)
   • Elton will obtain cost estimates for this power supply
2. Cryogenic plant: Primary circuit: Forced flow He at 4.5K, < 10g/s, ~5-10 bar, pressure drop < 2 bar. Secondary circuit: Deliver intermediate temperature He gas at 20-70 K to HTS vapor cooled current leads
   • Jonathan will investigate feasibility/cost of modifying existing refrigerator or purchasing new to deliver these requirements. Provide details to Ettore
3. High-current HTS (17KA) vapor cooled leads
   • Ettore will provide this information based on Sultan design
4. Fast protection system (external), with response time of ~0.5 s. Commercial 4 parallel breakers 5KA each (20KA total), 2KV max. Two independent systems for redundancy.
   • Ettore will obtain details of these existing systems.

Tentative Agenda

1. Power supply
   • maximum current capability
   • How much the PS can be modified to increase the current capability
   • bus bar capability. Can cables be used, or are air/water cooled bus bars required?

1. Cryogenic plant
   • Is a secondary loop practical/feasible with an intermediate heat exchanger and recirculating pump in order to comply with the pressure (~6 bar) and pressure drop (~0.5 bar) needed for the CIC conductor.

Minutes

Attending Morning: Joe Minervini, Phil Michael, Elton, Ettore, Glenn, Lionel Quettier, Mitch Laney, Catherine Ware (MIT Chief Fiscal Officer on the phone),

1. Drawings
   • Add space envelop for cryogenic can/connections on top of magnet. Drawing should include expected iron cladding. Also add location of transfer lines. (Tim)
   • Provide building information for use in considerations of installation and operation. Hall D has a 20 T crane.
   • Update B-field table with values for "preferred shape" (LASS values) (Elton)
   • Saturation curve for steel. (Tim suggest the use of 1010 steel properties)
   • Specify radiation environment in hall. To start give power deposited per volume inside coils. [Note: For Hall D rates this will likely not be a problem, but good to document] (Elton)
2. Requirements and Interface Document (MIT will start with draft and iterate with JLab)
   1. Items to add in random order
      • duty cycle of magnet
      • possibility of reversing polarity (start assuming reversing should be possible, but infrequent --check protection system and diode stacks)
      • consider assembly and operations
      • add specification of 5 G boundary
      • Investigate operation of magnet at 2.5 T with existing design with out modifications.
      • Revisit saturation of iron by adding iron to fill in regions currently occupied by existing magnet infrastructure. Could possibly also add more iron in "coil volume" for thinner coil
   2. Implementation
      • MIT to provide server read access to documentation
      • JLab to approve and keep controlled documents
3. Discussion of Hall B experience with Rutherford cable (Lionel)
   • Lionel showed pictures and discussed Hall B experience with soldering the Rutherford cable into Cu channel.
4. Procurement issues
   • terms and conditions seem to be ok on first glance
   • MIT will give feedback to Mitch as soon as possible.
   • An extension of the RFP will be granted to allow for necessary review time.
5. Discussion: Why investigate the CIC option?
   1. Qualitative arguments (Ettore)
      • higher current -> less conductor -> fewer splices inside windings, more robust
      • higher current density -> more compact coil, possible gain in performance
   2. Comments and discussion
      • could lead to higher cryogenic loads
      • pricing of high temp leads might be high. Ettore: Should use existing HT current lead design, even for higher performance to save design/testing effort. HT lead designs include 6kA (CERN), 17kA (Sultan)
      • Note: burn out time for leads ~ 10x fast dump time.
      • Might require intermediate temperature for current leads of about 50-70k, below 80k for nitrogen. [Ganni commented later that 4K should be used with adjustable flow rate to adjust temperature]

Attending Afternoon discussion on infrastructure: Ettore, Elton, Joe, Phil, George Biallas, Tim Whitlatch, Elliott Wolin, Jonathan Creel, Rao Ganni.

1. Power Supply
   • Guestimates of modifying existing power supply for currents exceeding 3KA would not save much compared to purchasing a new supply at about $150K.
   • Decision not to constrain the conceptual design for either conductor type by attempting to use existing supply. New PS would also be outfitted with a new dump resistor and protection system.
2. Cryoplant
   • Ganni emphasized that secondary pump loop was not effective use of resources (modification costs equalled new refrigerator and maintenance problematic)
   • Existing refrigerator could be reconfigured to provide a 5-6 atmosphere input pressure to provide an output pressure of about 3 atmospheres. This should be sufficient for even the CIC design, but implementation can be reviewed at the time that the conceptual design provides actual parameters.
   • Existing refrigerator should be able to handle a magnet consuming 50W at 5g/s. Current magnet operates at 100W at 0.3 g/s.
   • Intermediate temperature for HT leads: Rao suggests using 4K liquid, and adjusting the flow to achieve the desired temperature.
   • Preferred option is to use a bath, but other options can be accommodated depending on the magnet design
   • Jonathan (Rao) will provide a spec sheet for the cryo plant to MIT