Construction of superconducting RFQs at INFN-LNL

Abstract

The construction of SRFQ2, the first built superconducting RFQ for the low velocity accelerator PIAVE (injector of the SC linac ALPI at INFN-Legnaro) was completed.It resonates at 80 MHz, it is made of full niobium and it is mechanically stiffened by a titanium jacket which is welded by electron beam welding on the tank. The cavity is about 0.8 m both in length and in diameter. After completion of the mechanical construction, the structure went under a number of experimental tests, which are reported in the paper, in order to check: voltage unbalance among the four quadrants through bead-pulling; vacuum tightness; frequency change under vacuum and additional external pressurization; frequency change between 300 and 77 K; frequency change given by stepwise chemical etching of the internal surface.The paper reports as well the most recent achievements obtained when the resonator was mounted into the cryostat, purpose-built to test it in the superconducting regime, and cooled down to the working temperature.

Design of a 162.5 MHz Superconducting Radio-Frequency Quadrupole for High-Intensity Proton Acceleration

“…As discussed above, SC RFQs are going to be an indispensable part of the low-energy end of high-intensity accelerators. However, due to numerous challenges in the design and construction of SC RFQs, only the National Institute for Nuclear Physics (INFN) in Italy successfully built two 80 MHz SC RFQs around 2000, which have been in steady operation for a long time [19][20][21][22][23]. It is urgent to conduct further research on SC RFQs.…”