A. Martinez

Design and testing of the New Muon Lab cryogenic system at Fermilab

Fermi National Accelerator Laboratory is constructing a superconducting 1.3 GHz cryomodule test facility located at the New Muon Lab building. The facility will be used for testing and validating cryomodule designs as well as support systems. For the initial phase of the project, a single Type III plus 1.3 GHz cryomodule will be cooled and tested using a single Tevatron style standalone refrigerator. Subsequent phases involve testing as many as two full RF units consisting of up to six 1.3 GHz cryomodules with the addition of a new cryogenic plant. The cryogenic infrastructure consists of the refrigerator system, cryogenic distribution system as well as an ambient temperature pumping system to achieve 2 K operations with supporting purification systems. A discussion of the available capacity for the various phases versus the proposed heat loads is included as well as commissioning results and testing schedule. This paper describes the plans, status and challenges of this initial phase of the New Muon Lab cryogenic system.

SUPERCONDUCTING RADIO-FREQUENCY MODULES TEST FACILITY OPERATING EXPERIENCE

Fermilab is heavily engaged and making strong technical contributions to the superconducting radio-frequency research and development program (SRF R&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 the SRF R&D needs. The projects first stage 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 Meson Detector Building (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.

Surge recovery techniques for the Tevatron cold compressors

The Fermilab Tevatron cryogenic system utilizes high‐speed centrifugal cold compressors, made by Ishikawajima‐Harima Heavy Industries Co. Ltd. (IHI), for high‐energy operations. The compressor is designed to pump 60 g/s of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off‐design range of 40 to 70 g/s and operating speeds between 40 and 95 krpm. Since initial commissioning in 1993, Tevatron transient conditions such as quench recovery have led to multiple‐location machine trips as a result of the cold compressors entering the surge regime. Historically, compressors operating at lower inlet pressures and higher speeds have been especially susceptible to these machine trips and it was not uncommon to have multiple compressor trips during large multiple‐house quenches. In order to cope with these events and limit accelerator down time, surge recovery techniques have been implemented in an attempt to prevent the compressors from tripping once the machine entered this surge regime. This paper...

Cryogenic system for the Cryomodule Test Facility at Fermilab

This paper provides an overview of the current progress and near-future plans for the cryogenic system at the new Cryomodule Test Facility (CMTF) at Fermilab, which includes the helium compressors, refrigerators, warm vacuum compressors, gas and liquid storage, and a distribution system. CMTF will house the Project X Injector Experiment (PXIE), which is the front end of the proposed Project X. PXIE includes one 162.5 MHz half wave resonator (HWR) cryomodule and one 325 MHz single spoke resonator (SSR) cryomodule. Both cryomodules contain superconducting radio-frequency (SRF) cavities and superconducting magnets operated at 2.0 K. CMTF will also support the Advanced Superconducting Test Accelerator (ASTA), which is located in the adjacent New Muon Lab (NML) building. A cryomodule test stand (CMTS1) located at CMTF will be used to test 1.3 GHz cryomodules before they are installed in the ASTA cryomodule string. A liquid helium pump and transfer line will be used to provide supplemental liquid helium to ASTA.

Cryogenic controls for Fermilab's SRF cavities and test facility

A new superconducting radio frequency (SRF) cavities test facility is now operational at Fermilabs Meson Detector Building (MDB). The Cryogenic Test Facility (CTF), located in a separate building 500 m away, supplies the facility with cryogens. The design incorporates ambient temperature pumping for superfluid helium production, as well as three 0.6 kW at 4.5 K refrigerators, five screw compressors, a helium purifier, helium and nitrogen inventory, cryogenic distribution system, and a variety of test cryostats.To control and monitor the vastly distributed cryogenic system, a flexible scheme has been developed. Both commercial and experimental physics tools are used. APACS+™, a process automation control system from Siemens-Moore, is at the heart of the design. APACS+™ allows engineers to configure an ever evolving test facility while maintaining control over the plant and distribution system. APACS+™ nodes at CTF and MDB are coupled by a fiber optic network. DirectLogic205 PLCs by KOYO® are used as the f...

SCRF Cryogenic Operating Experience at FNPL

The Fermilab‐NICADD Photoinjector Laboratory (FNPL), a photoelectron research and development beam line, has been operational since 1998. A single TESLA 9‐cell superconducting RF cavity is operated in support of this accelerator system. The superfluid cryogenic system consists of a dewar‐fed liquid helium supply with up to 2 g/s vacuum pumping capacity. Helium gas is recovered to the Tevatron cryogenic system. The photoinjector static load is about 2.5 W to 1.8 K, with a typical dynamic component of about 0.5 W. The capabilities, performance, operating experience, and reliability of this superfluid cryogenic system will be discussed. An auxiliary cryogenic system for testing bare superconducting RF cavities in a vertical dewar is also available, providing a steady state capacity of about 12 W at 1.8 K for testing.

Pressure Field Study of the Tevatron Cold Compressors

The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations [1]. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40 and 95 krpm, with a speed of 80 krpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper.

Report on the First VLHC Photon Stop Cryogenic Design Experiment

As part of Fermilab’s study of a Very Large Hadron Collider (VLHC), a water‐cooled photon stop was proposed as a device to intercept the synchrotron radiation emitted by the high‐energy proton beams in the high‐field superconducting magnets with minimal plug‐cooling power. Photon stops are radiation absorbers operating at room temperature that protrude into the beam tube at the end of each bending magnet to scrape the synchrotron light emitted by the beam one magnet up‐stream. Among the technological challenges regarding photon stops is their cryo‐design. The photon stop is water‐cooled and operates in a cryogenic environment. A careful cryo‐design is therefore essential to enable operation at minimum heat transfer between the room temperature sections and the cryogenic parts. A photon stop cryo‐design was developed and a prototype was built. This paper presents the results of the cryogenic experiments conducted on the first VLHC photon‐stop prototype.

Critical Speed Measurements in the Tevatron Cold Compressors

The Fermilab Tevatron cryogenic system utilizes high‐speed centrifugal cold compressors, manufactured by Ishikawajima‐Harima Heavy Industries Co. Ltd. (IHI), for high energy operations. Nominal operating range for these compressors is 43,000 to 85,000 rpm. Past foil bearing failures prompted investigation to determine if critical speeds for operating compressors fall within operating range. Data acquisition hardware and software settings will be discussed for measuring liftoff, first critical and second critical speeds. Several tests provided comparisons between an optical displacement probe and accelerometer measurements. Vibration data and analysis of the 20 Tevatron ring cold compressors will be presented.