ILCTA – Cryomodule Assembly Buildings

Fermilab’s Cryomodule Assembly Facility consists of two areas: MP9 and the Industrial Center Building. MP9 is a 12,000-square-foot facility, which was designed using DESY laboratory’s Hall 3 facility in Hamburg, Germany as a guide. Fermilab’s new facility consists of a clean room, cavity string assembly rail and cold mass assembly fixture that will be used for lab’s 1.3 GHz and 3.9 GHz superconducting cavity programs. The Industrial Center Building is an 18,000–square-foot production floor building, which will accommodate two parallel cold mass assembly areas and final assembly areas in order to achieve the ultimate throughput for the facility -- one cryomodule per month.

Technicians stringing superconducting cavities together in Fermilab’s clean room.

Inside this facility, Fermilab engineers and scientists receive chemically processed bare cavities for ILC R&D. These cavities are prepared for the vertical test. If the test is successful, these cavities then get welded inside a helium vessel. The cavities also get further chemically processed and dressed with a power coupler in the clean room and then further dressed with a tuner and magnetic shielding. If the cavity achieves the desired acceleration gradient during the horizontal test in Fermilab’s new Horizontal Test Stand, it returns to the clean room to be assembled into a string of eight cavities for eventual inclusion in a cryomodule. (If the cavity fails the horizontal test, it needs to be further processed and/or high pressure rinsed.)

Inside the facility at MP9, Fermilab engineers and scientists receive chemically processed bare cavities for ILC R&D. These cavities are prepared for the vertical test. If the test is successful, these cavities then get welded inside a helium vessel. The cavities then get dressed with a power coupler in the clean room. A tuner and magnetic shielding get added before heading off for high power radiofrequency testing in the Horizontal Test Stand. If the cavity achieves the desired acceleration gradient in the test stand it returns to the clean room to be assembled into a string of eight cavities for eventual inclusion in a cryomodule. (If the cavity fails the horizontal test, it needs to be further processed and/or high pressure rinsed.)

Fermilab’s Industrial Center Building awaits a string of superconducting cavities to assemble the first cryomodule.

The string of eight cavities then gets mated with a cold mass and transported to the Industrial Center Building for final assembly. In this area, additional instrumentation is attached and the cavities are aligned. The cavity assembly is then inserted into a vacuum vessel, and the warm couplers get attached, resulting in a completed cryomodule ready for testing in the ILC Test Area that is being built at the New Muon Laboratory.

A large effort went into constructing the optimal clean room for ILC R&D. The 2500-square-foot clean room is divided into three sections to accommodate each stage of the labor intensive assembly process. Rated according to the number of particles per cubic foot, the clean room contains a Class 1000, Class 100 and Class 10 area. The first section, a Class 1000 Ante Clean Room, is a prep room where the cavities and other peripheral parts get submerged in ultrasonic baths and blown with ionized nitrogen to reduce the particle count to less than 10 - a critical step before entering the next stage of the assembly process.

The class 10 area, which is used to assemble the dressed cavities to form a string, has more filters and more floor perforations in it to constantly keep air flowing. Every six seconds 100% of the air in the clean room changes with approximately 90 feet per minute laminar air flow speed. While designing the clean room, Fermilab worked closely with DESY scientists and engineers, who described their ideal clean room scenario, and consultants, who specialize in building clean rooms for major corporations.

The cavity string assembly rail inside the MP9 section of Fermilab’s Cryomodule Assembly Building.

Any person who enters the room must first “gown up” in special head to toe gear – no make-up, perfume or lotion allowed, and this is just a small part of the strict clean room protocols that will be enforced for the cavity string assembly clean room.

Fermilab is currently using the Cryomodule Assembly Facility to assemble the first cryomodule. Parts for this cryomodule have been arriving from DESY, essentially as a “cryomodule kit” that consists of approximately 1200 components. Fermilab will work closely with DESY scientists, engineers and technicians to assemble this first cryomodule for ILC R&D. Fermilab estimates that this first cryomodule will take approximately four months to assemble, but after a learning curve, the goal is to produce one cryomodule per month. In parallel, Fermilab scientists are working closely with DESY to build a 3.9 GHz cryomodule for the DESY FLASH machine in Hamburg. The 3.9 GHz cryomodule will use much of the same infrastructure in the Cryomodule Assembly Facility and is another high priority superconducting radiofrequency project at Fermilab.

Cryomodule Assemble Facility- Update (ppt, 30.8MB)