Upgrade of the Tevatron Cryogenic System
Fermilabs superconducting Tevatron accelerator has reached its tenth year of operation. This year, three significant upgrades to the cryogenic system will become operational; a second central helium liquefier, a Tevatron satellite refrigerator lower temperature upgrade, and a satellite refrigerator controls system upgrade.
The decision to build a second central helium liquefier (CHL) was originally based on redundancy; protecting accelerator operation from a major CHL failure such as a heat exchanger. Higher capacity turbines were used in the second coldbox, which will result in an estimated 5400 liters per hour production rate. Preliminary commissioning of the coldbox took place in 1992. Full capacity testing will take place in 1993.
To aid in the discovery of the top quark, it is desirable to increase the particle energy in the Tevatron accelerator. The machine is limited to an energy of 900 GeV due to magnet conductor short sample current at the existing operating temperature. An upgrade is underway to lower the temperature of the accelerator ~1K. The short term goal is 1000 GeV operation with a 1100 GeV long term goal. Cold vapor compressors will be used in each of the 24 satellite refrigerators to achieve the temperature reduction.
An upgrade of the existing satellite refrigerator controls system is necessary to incorporate the added control devices, instrumentation, and controls algorithms required by the low temperature upgrade. The existing Z80 Multibus I based system will be replaced with a 386 Multibus II system. New features will be incorporated, including processor to processor communications, fast event driven circular buffer, hierarchical alarm system, higher level language support, and more elaborate controlling algorithms.
KeywordsHeat Exchanger Cryogenic System Circular Buffer Cold Compressor Cryogenic Engineer
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