Operational Experience of the NML Cryogenic Plant at the FAST Test Facility

TL;DR

This paper details the operational experience, performance metrics, and outages of the NML cryogenic plant used for cooling SRF cavities at the FAST facility over multiple science runs since 2019.

Contribution

It provides a comprehensive account of the cryogenic plant's operation, performance, and reliability in a real-world accelerator environment, highlighting practical insights.

Findings

High availability of the cryogenic system over multiple science runs

Identification of common outages and their causes

Performance data demonstrating effective cooling of SRF cavities

Abstract

The NML cryogenic plant cools two individually cryostated superconducting radio frequency (SRF) capture cavities and one prototype ILC cryomodule with eight SRF cavities. This complex accelerates electrons at 150 MeV for the Integrable Optics Test Accelerator (IOTA) ring, located at the Fermilab Accelerator Science and Technology (FAST) facility. The cryogenic plant is composed of two nitrogen precooled Tevatron satellite refrigerators, two Mycom 2016C compressors, a cryogenic distribution system, a Frick purifier compressor, two charcoal bed adsorber purifiers, and a liquid ring vacuum pump with a roots booster. The SRF cavities are immersed in a 2.0 K liquid helium bath, shielded with a 5 K gaseous helium shield and a liquid nitrogen cooled thermal shield. Since 2019, this R&D accelerator complex has gone through four science runs with an average duration of 12 months. Operational experience for each run, availability metrics, performance data and common outages are presented in this paper.