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EVLA Front-End CDR

EVLA Front-End CDR. Cryogenic & Vacuum Systems. Cryogenics &Vacuum Systems Overview. EVLA Required Cryogenics and Vacuum System Upgrades Design Parameters Gas flow system Vacuum system Hardware Compressors Drivers. EVLA Upgrades. EVLA upgrades to the receiver system include:

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EVLA Front-End CDR

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  1. EVLA Front-End CDR Cryogenic & Vacuum Systems EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  2. Cryogenics &Vacuum SystemsOverview • EVLA Required Cryogenics and Vacuum System Upgrades • Design Parameters • Gas flow system • Vacuum system • Hardware • Compressors • Drivers EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  3. EVLA Upgrades • EVLA upgrades to the receiver system include: • S-Band (New) • Ka-Band (New) • C-Band (relocated out of the “A” rack) • Ku-Band (relocated out of the “A” rack) The impact is, a higher gas flow rate and a higher volume vacuum requirement. EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  4. Gas Flow System Design Parameters • Three Types of Coldheads used in system • Type 1020 Coldhead: 28 scfm • Type 350 Coldhead: 17 scfm • Type 22 Coldhead: 9 scfm EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  5. Gas FlowSystem Design Parameters • EVLA gas flow requirements dictated that a third helium compressor be installed. • Compressor A circuit requires 43 scfm • S(350), Ku(350), Q(22) • Compressor B circuit requires 43 scfm • X(22), K(350), Ka(350) • Compressor C circuit requires 45 scfm • L(1020), C(350) EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  6. Compressor B Helium Compressors Compressor A Compressor C EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  7. Vacuum System Design Parameters • EVLA vacuum requirements resulted in the smaller of the two VLA pumps being replaced with a larger unit. • Vacuum Pump A circuit • X, C, S, Ku • Vacuum Pump B circuit • Ka, K, Q, L EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  8. Vacuum SystemPump Controlled by the card cage EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  9. HardwareCompressors • Compressor modifications justification: • CTI discontinued the 3 HP piston type compressor. • Refurbished CTI 1020R compressors are $11,500 each. • CTI 1020R compressors were rated at 51 scfm, but had a higher gas discharge temperature than NRAO compressors • NRAO modified and built a compatible compressor at a cost of $4600, which is rated at 48scfm. EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  10. HardwareDrivers • Coldhead Drivers • New Scott-T boxes • Designed, tested and installed • Designed to work with the new receiver card cages • Not compatible with the old style card cage • Each Scott-T will drive up to 4 coldheads • Interim • Used the old style coldhead drivers until new card cages are installed EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  11. New Scott-T Boxes HardwareColdheadDrivers EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

  12. Summary • Discussed the additional Helium gas flow need for EVLA, that resulted in the addition of a third circuit. • Discussed the new Scott-T coldhead drivers. • Discussed cost savings related 1020R compressor modifications. • 87% of Cryo budget has been expended to date; • Purchased 104 model 350 coldheads • Purchased 30 Helium compressors • Remaining budget is sufficient to cover ancillary hardware. EVLA Front-End CDR – Cryogenic & Vacuum Systems April 24, 2006

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