Piezo Tuning System (PTS) developed at Saclay

Saclay Piezo Tuning System (PTS) Purpose: Design of a new PTS that can be mounted on a TTF cavity (present design of cavity and He tank without any modification) Fabrication of 2 PTS Tests RF power tests of C45 TTF cavity in CRYHOLAB (WP10 – Bernard Visentin) Mechanics + electronics development: G. Devanz – E. Jacques - S. Leducq – M. Luong (DAPNIA/SACM) Bo Wu (DAPNIA/SIS)

Mechanical principle of the present TTF tuner Mechanical studies Mechanical principle of the present TTF tuner Design by M. Maurier and P. Leconte based of the MACSE tuner design DLscrew DLarms DLcavity Double lever system: ratio ~ 1/17 Stepping motor with Harmonic Drive gear box Screw – nut system D Zmax = ± 5 mm and D Fmax = ± 2.6 MHz theoretical resolution: dz = 1.5 nm ! Orientation of the forces: the cavity is always compressed the tuner fixations are stretched fixation on Cavity fixation on He tank fixation on He tank

Mechanical studies Stiffness increased by reversing the forces The piezo support is pulled Fpull≈ Fcav/2 Fcav < 10 kN Fcompress Present piezo TTF tuner: The piezo actuator shall be kept in compression by its support: Fcompress The effective preload strength on the stack is: Fpreload ≈ Fcompress - Fcav/2 The stiffness of the whole tuning system is degraded by the piezo support which shall have a flexibility to allow piezo elongation and a good preload control. Reversing the strength direction: by stretching the cavity, the strength would be applied on the stack only by the cavity extension. A higher tuner stiffness would be conserved.

suppressing the asymmetry Mechanical studies suppressing the asymmetry A second lever can be added in order to obtain a symmetric movement allowing long tuning range keeping strengths parallel to the axis of the cavity. SOLEIL and Super-3HC cryomodules have such tuner design without piezos. (the Super-3HC tuner)

Mechanical studies piezos frame 2 flexible steel foils for transverse force transmission and axial piezo stroke transmission Transverse force due to lever system Load applied by the cavity elasticity Helium tank fixation Flexibility of the support for lowering the transverse forces piezos frame 2 piezos actuators Piezo actuator size: L= 30 to 36 mm 2 piezo stacks in a symmetric position guided by 2 flexible steel foils for axial stroke transmission without friction

Mechanical studies Question: do we need a system to equilibrate the load between the 2 piezos stacks mounted on the tuner ? piezos support => Our first design is without any adjustment system. A precise machining of the pieces + the toppling of the tuner components should allow to equilibrate the compression load on the 2 piezos. Conical support piezo Spherical support glued on the piezo stack Experience will tell us if an adjustment system is necessary Length (51 mm) precisely machined (+0.005, -0) Once the two conical supports are machined, these 5 elements will be matched together

Mechanical studies piezos support Do we need a preloading system ? Requirement for the tuner design: the cavity shall be always stretched (suppression of the mechanical plays for minimizing the backslash). Typical force applied by the cavity is about 2000 N (0.5 to 1 mm deformation). It is possible to increase this force up to about 7000N (cavity stretched by about 2 mm from zero point at cold) while keeping the cavity in elastic deformation (in the whole range 300K-2 K). In that case, if the force is equally distributed, each piezo should see about 1600 N, which is an interesting preload value. First design without any preloading system

A pneumatic jack was used to apply forces up to about 7000N 2 PTS fabricated Tests on a bench at 300K A pneumatic jack was used to apply forces up to about 7000N Results: Stiffness estimation : 35 kN The flexibility is mainly due to the ball bearing housings Working of the “slow” tuner: OK (stepper motor, gear box, mechanical lever, …)

Tests on C45 TTF cavity at 300K Control system developed at Saclay for the integrated tests in CRYHOLAB Phase Demodulator Arbitrary waveforms Generator Demultiplexer Multiplexer PC GPIB RS232 i/o 6602 N.I. Digital Scope RF Amplifier (Solid state,IOT,on klystron) Capacitance meter RF Control System Motor Driver Piezo Driver Piezo Sensor Signal Conditionning FM Demodulator Locking Amplifier Tuner Piezo Actuator Motor Sensor RF coupler RF pick-up trig 1 2 3 Trig

Tests on C45 TTF cavity at 300K After RF power test of C45 cavity in CRYHOLAB (WP10 – Bernard Visentin) the tuner was mounted on the cavity for tests in the laboratory. Tests program outside CRYHOLAB (no precise RF measurements available): Identification and characterization of the mechanical modes: F, Q, piezo to piezo transfer function Influence of the cavity stretching force on the piezo sensor response (by moving the stepper motor) Tests performed with NOLIAC piezos PZT-S2 (pz29) L=30mm, 10x10mm

Piezo to piezo transfer function PTS Signal generator Piezo driver gain G X Piezo actuator 9-cells cavity Piezo sensor Y GPIB Oscilloscope Harmonic analysis X(w) = G sin(w) Steady state of linear system Y(w)=|Y| sin(w+f) PC+Labview X : piezo actuator voltage Y : piezo sensor voltage Transfer function H(w) = Y(w)/X(w)

Tests on C45 TTF cavity at 300K Amplitude and phase signal of the transfer function of one piezo to the other. The tests are still in progress (linearity, influence of the stretching of the cavity, …) Quality factors of several modes are being determined

Tests on C45 TTF cavity at 300K The cavity will be mounted in CRYHOLAB at the end of week 42 Tests at 300 K in CRYHOLAB: end of October - beginning of November Analysis of the CRYHOLAB environment influence on the mechanical modes (main coupler fixation, insulating vacuum, helium tank vacuum, etc.) RF measurements will allow the analysis of the piezos to detuning transfer function

Piezo to detuning transfer function PTS X Piezo actuator 9-cells cavity Y Piezo sensor Electrical Mechanical RF X : piezo actuator voltage Y : cavity detuning electric Transfer function H(w) = Y(w)/X(w)

Tests on C45 TTF cavity in CRYHOLAB (WP10) The cavity will be cooled down for integrated RF power tests in CRYHOLAB at mid of November. These tests are scheduled until the end of the year.