[en] Heat leak measurements on magnet strings and transfer line were taken during the latest run of the A1 and A2 satellite refrigerators this past summer. Methods and results are discussed in this report

[en] The impetus for this design report originated in the Snowmass 88 meeting where the subject of higher energies within the constraints of the existing Tevatron tunnel enclosure was investigated. It was determined that beam transport to the fixed target experimental areas was possible up to an energy of ∼1.5 Tev. Collider operation was feasible at somewhat higher energies (1.8 Tev), primarily limited by the ability to design a single turn beam abort system within the constraints of the straight section length. A new accelerator in the existing tunnel would, of necessity, have a similar though not identical lattice and straight section layout to the present Tevatron. Thus when issues arose in the magnet design requiring input from the accelerator standpoint we have assumed a Tevatron like machine. The possibility of using these high field magnets as elements in the existing Tevatron to create new 'warm space,' for another Interaction Region for example, also emphasizes compatibility with the present machine. 16 refs., 62 figs., 23 tabs

[en] This report is based on the past 12 years of experiments on R and D and operation of the 27 kW Fermilab Tevatron Cryogenic System. In general the comments are applicable for all helium plants larger than 1000W (400 l/hr) and non mass-produced nitrogen plants larger than 50 tons per day. 14 refs., 3 figs., 1 tab

[en] The Tevatron refrigeration system is described, specifically the design transfer line cross-section. A cross-section and one section Tevatron feed line are illustrated. One pair of Tevatron U-tubes and the transfer line test layout are also illustrated. The fabrication and installation are described. Cooldown and warmup tests are reported with the operation and heat leak measurements given. Current work includes flow instabilities. Preliminary results indicate that heat loads are similar to previous measurements

[en] The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.

[en] The start-up of any large system can be broken into three phases: (1) component debug, (2) commissioning and (3) operations. The component debug phase consists of getting the rotating machinery working reliably as well as getting major subsystems operational such as coldboxes. In addition, for computer controlled systems, one must get the control software and a significant fraction of the application diagnostics operational. The 13 years of experience on R and D and operation of the 27 kW Fermilab Tevatron Cryogenic System are described

[en] The Energy Saver Refrigeration System is based on the concept of a central helium liquefier (5000 l/hr) providing liquid to 24 satellite refrigerators (966 W at 4.6/degree/K), which operate as amplifiers with a gain of 12. This concept was tested, cooling two 125 m long strings of superconducting magnets. The test was run using one satellite refrigerator operating as the ''central liquefier'', shipping liquid helium through a 250 m long transfer line to a second satellite refrigerator, which in turn cooled the magnets. In addition to testing the satellite concept, the heat loads of the magnets and transfer line were also measured. 3 refs

[en] The Tevatron magnets at Fermilab are cooled by a hybrid system which consists of a 5000 liters/hr central helium liquefier coupled with a small-diameter liquid transfer line connecting twenty-four satellite refrigerators. The transfer line supplies liquid helium for both the refrigerators and the magnet lead flow as well as liquid nitrogen for the magnet shields. The satellites act as amplifiers with a gain of twelve by using the enthalpy of the helium supplied by the central liquefier as liquid and converting it to 4.5-K refrigeration and then returning it as 300-K gas. This arrangement combines the advantages of a single central facility with those of individual stand-alone units stationed around the ring. The central liquefier has the high efficiency associated with large components but its requirements for distribution of both cryogenic liquids and electric power to the service buildings is reduced. The six compressor buildings supply 20 atm helium to the twenty-four refrigerators through a discharge header located on the berm and a suction header located in the tunnel. The compressor buildings each have four-two stage 58 g/sec screw compressors; each of these has its own oil removal system. The inventory in the ring is controlled at the first compressor building through a cross-connect line to the central liquefier. The suction header is also used as the cooldown line as well as for quench relief. A third header located in the tunnel is the nitrogen collection and relief header

[en] Fermilab is heavily engaged and making strong technical contributions to the superconducting radio-frequency research and development program (SRF R and D). Four major SRF test areas are being constructed to enable vertical and horizontal cavity testing, as well as cryomodule testing. The existing Fermilab cryogenic infrastructure has been modified to service Fermilab SRF R and D needs. The first stage of the project has been successfully completed, which allows for distribution of cryogens for a single cavity cryomodule using the existing Cryogenic Test Facility (CTF) that houses three Tevatron satellite refrigerators. The cooling capacity available for cryomodule testing at MDB results from the liquefaction capacity of the CTF cryogenic system. The cryogenic system for a single 9-cell cryomodule is currently operational. The paper describes the status, challenges and operational experience of the initial phase of the project

[en] Fermilab has constructed a facility for testing dressed superconducting radiofrequency (RF) cavities at 1.8 K with high-power pulsed RF. This test stand was designed to test both 9-cell 1.3 GHz TESLA-style cavities and 9-cell 3.9 GHz cavities being built by Fermilab for DESY's TTF-FLASH facility. An overview of the test stand and a description of its initial commissioning is described here