Institute of research into the fundamental laws of the Universe

Technical means

• Liquid Helium cooling: a refrigerator unit producing 140 l/h and 2000 l buffer tanks for each vertical cryostat, allowing one to provide helium at 4.2 K or 1.8 K by pumping on the helium bath. 500 l liquid helium are consumed for a typical cavity test in CV1, and 1500 l in CV2.
• RF sources with adjustable frequency and power (80-90 MHz 50 W; 170-180 MHz 500 W; 700-1500 MHz 200 W; 704 MHz 1 kW), controlled via PLL based closed circuit loop.
• Measurement of incident, transmitted and reflected RF power; estimation of heat losses via helium consumption (level drop or flowmeter).

Achievements, related projects

• Single cell cavities to prototype new cavity preparation methods (etching, rinsing, heating, doping, ….),
• XFEL, SPL, ESS elliptical cavity prototypes,
• 12 Spiral2 quarter-wave cavities qualification,
• IFMIF half-wave cavities qualification,
• SARAF, LUCRECE, DONES
• HIPPI, TTF
• PIP2

Technical steps, expertise

• Mounting of the cavity on vertical insert, vacuum leak tests, installation of thermal probes,
• Positioning of the insert into the cryostat, connection to pumping lines and RF coax lines,
• Leak checks and low power RF checks at room temperature,
• Cooling down to 4.2 and / or 1.8 K, with fast ramps (3 K / min) from 150 to 50 K,
• Control of the cavity frequency, the field ramp in the cavity by injecting increasing RF power and concurrent measurement of quality factor deduced from Pi, Pt, Pref.