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MOP075 |
A X-rays Shielded Facility Dedicated to Cryogenic RF Tests of Fully Dressed Spoke Cavities in the Cryomodule CM0 at IPN Orsay | |
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| A bulk Nb superconducting β=0.3 Triple-Spoke (T-Spoke) cavity operating at 352 MHz, was designed at IPN and fabricated thanks to EURISOL project financial support. The cavity will be tested in November 2013 at a new X-rays shielded facility dedicated to cryogenic tests of fully dressed (LHe tank, Magnetic Shields, Fast Active Cold Piezoelectric Tuning System (FACPTS), RF Power coupler) Spoke cavities in the horizontal cryomodule CM0. The CW RF power and cryogenic power @T=2K are 80kW and 120W respectively. Four vertical cold RF tests were performed in a vertical cryostat and the data are reported. All components (cold box, cryogenic lines, He gas heater, RF power system with 2 RF power couplers, LHe bath pumps) were delivered and successfully tested. The cryogenic circuit in CM0 was finished and we successfully mounted the fully dressed T-Spoke cavity. A R.T tuning system was used for static and dynamic mechanical measurements on Single (S-Spoke) and T-Spoke cavities. Mechanical stiffness, transfer function, vibrations, Lorentz detuning were investigated using the FACPTS. Field profile in S-Spoke and T-Spoke cavities were performed using a motorized field perturbation stand. | ||
| TUP103 | Calibration and Characterization of Capacitive OST Quench Detectors in SRF Cavities at IPN Orsay | 714 |
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Funding: IPNO/IPN2P3/CNRS The maximum RF surface magnetic field (Bs) achieved with SRF bulk Nb cavities is often limited by anomalous losses due to Joule heating of normal-resistive defects embedded onto the RF surface. At high BS (e.g Bs>50 mT), the defect temperature increases strongly with BS, leading to a thermal runaway of the cavity or quench. The unloaded quality factor Q0 of the cavity decreases suddenly and strongly due to superconducting to normal state phase transition of the hot spot area. Quench detectors, called Oscillating Superleak Transducer (OST) and sensing 2nd sound events in He II, have been recently used to study quench of SRF cavities. IPN developed his prototypes of OST quench detectors and a test stand for their calibration and characterization in the temperature range T0=1.6 K-2.2 K. This device allows precise and controlled experimental simulation of SRF cavity quench using pulsed heat sources. Experimental runs were performed to study the dynamic response of OST detectors when the heat source is subjected to a time varying heat flux q(t) as function of several parameters (T0, q(t) time structure and density, heat source size) and first experimental data are presented. |
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