Low Temperature RF Test of Two-cell SRF Prototype Cavity for PEFP

To confirm the design and fabrication procedures and to check the RF and mechanical properties of a low-beta elliptical SRF (Superconducting Radio-Frequency) cavity, a niobium cavity with two cells has been designed and fabricated as a prototype PEFP SRF cavity. For the test at low temperature of 4.2 K, a cryostat was designed and fabricated. The cryostat was thermally insulated with 40 layers of super-insulations and the vacuum jacket and equipped with temperature monitors and liquid level meters. The RF system for driving the cavity is based on PLL (phase locked loop) to main the resonance condition. The cavity was cooled to 4.2 K with liquid helium to make cavity superconducting state. Total liquid helium consumption was about 620 liters during the experiment