HB 650 SCRF Cavity Tuner Vikas Kumar Jain

HB 650 SCRF Cavity Tuner Vikas Kumar Jain and Kuldeep Kumar Singh, PLSCD Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015

Status of Tuner Mechanism Development of 1. 3 GHz blade tuner mechanism • Development of blade tuner is taken up to understand the tuning issues. • Developed a prototype 1. 3 GHz 9 -cell RF cavity (copper) for tuner testing. • The blade tuners in SS and Ti were fabricated using laser welding. • Developed encapsulated piezo support. • Tuner mechanism is tested at 2 K with singlecell SCRF cavity. Laser welding of Blade Tuner Raja Ramanna Centre for Advanced Technology, Indore 1. 3 GHz Prototype cavity with Blade Tuner 1. 3 GHz. Single-cell Cavity with Blade Tuner IIFC Meeting - 24 -25 February, 2015

Tuner Mechanism Testing 1. 3 GHz blade tuner testing 1. Slow tuner testing • Development of current controlled driver for cryo-compatible motor for slow tuning. • Force & displacement measurement of tuner was done on dummy Helium vessel. • Mechanical & RF Tests of prototype dressed cavity at room temp (300 K) & LN 2 temp (77 K) were carried out for tuning range, tuner sensitivity, hysteresis etc. 2. Fast tuner testing • Development of piezo driver for fast tuning mechanism • Measurement of tuning range, tuner sensitivity, hysteresis at 300 K and 77 K on 1. 3 GHz 9 -cell prototype dressed cavity. • Measurement of tuning range, tuner sensitivity, hysteresis at 300 K, 77 K and 2 K (in VTS) on 1. 3 GHz single-cell SCRF cavity. • Fast tuner time response measurement. Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015

Tuner Testing with 1. 3 GHz 9 -cell Prototype Cavity Tuner tests have been carried out at 300 K and 77 K and the results of 300 K are as follows: • Slow tuning sensitivity : 320 Hz/mm. • Slow tuning range : ~300 k. Hz • Tuning efficiency : ~ 70% • Fast tuning sensitivity : 31 Hz/volt. • Fast tuning range: 6. 2 k. Hz Layout for fast tuning measurement scheme • Fast tuning response : 1. 2 msec 77 K Testing Raja Ramanna Centre for Advanced Technology, Indore Piezo excitation for fast response on SCRF cavity resonance IIFC Meeting - 24 -25 February, 2015

Tuner Testing with 1. 3 GHz Single-cell SCRF cavity • Tuner mechanism is tested at 2 K in VTS with single-cell SCRF cavity under superconducting state. • Same piezo driver has been used to drive the actuator by half sine wave. Characteristic of single-cell cavity tuner assembly for piezo DC excitation at 2 K. Comparison of fast tuner characteristics at different temp. Operating temperature 300 K 77 K 2 K Range of frequency shift with piezo actuator excitation to 200 V 82 k. Hz 34 micros (measured) 31. 5 k. Hz 10. 8 k. Hz Raja Ramanna Centre for Advanced Technology, Indore Hysteresis 11 k. Hz 2. 9 k. Hz 950 Hz Single-cell SCRF cavity with tuner Assembly for testing in VTS IIFC Meeting - 24 -25 February, 2015

HB 650 Cavity Tuner General requirement of tuning for 650 MHz b= 0. 92 SCRF cavity FANL FRS: for 650 MHz high beta superconducting dressed cavity; Doc. No. Doc. DB 1164; Version 2; Date: - 06/06/2013 Tuning system requirements Fermilab has suggested lever tuner design for 650 MHz b= 0. 92 SCRF cavity. Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015

HB 650 cavity tuner design and development Desirable initial inputs : 1. Latest approved FRS for 650 MHz b=0. 92 cavity giving complete details on tuner. 2. Details of FNAL 1. 3 GHz lever tuner will be help full for 650 MHz tuner development. 3. 3 D model and detail drawings of 650 MHz tuner with details for magnetic shielding and helium vessel. 4. Mechanism kinematics for both slow and fast tuning. 5. Specification of fast tuner and Piezo selection criteria and list of FNAL approved manufactures/ suppliers. 6. Methodology for Piezo characterization at 300 k and 4 K/2 K. 7. Specification of cryo-compatible motor for slow tuning and list of FNAL approved manufactures/ suppliers. 8. Circuit design details of the drivers for tuner (motor & piezo system). Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015

HB 650 Cavity Tuner Qualification For tuner qualification : - 1. “Traveler” format for tuner fabrication and testing. 2. Tuner test procedure (at room temperature and at 2 K in HTS) and its acceptance criterion. 3. Tuner pre-loading requirement and how to measure preloading after cool -down. 4. Details about the testing, assembly and stage wise dressing of 650 MHz, b = 0. 92, 5 -Cell SCRF cavity with Helium Vessel, Magnetic Shield and Tuner. 5. Sharing of Fermilab experience on tuner qualification. 6. Methodology and algorithm for LFD and microphonics corrections during operation. Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015

HB 650 Cavity Tuner Issues Additional issues related to development : 1. Acceptance criteria for microphonics detuning (df/dp), LFD and cavity tunability (stiffness). 2. Hysteresis 3. Tuner reliability for motor & piezo 4. Tuner accessibility (cold/ warm) for motor 5. Piezo-elements are closer to beam pipe in lever tuner è Radiation level will be higher (How much it will be during operations? ) è What is safe level for piezo? Thank you for your kind attention Raja Ramanna Centre for Advanced Technology, Indore IIFC Meeting - 24 -25 February, 2015