PHIN R Losito CERN ABATB 05092005 R Losito

PHIN R. Losito CERN – AB/ATB 05/09/2005 R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 1: Management Ø Website created Ø Maintainance and upgrade R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 2: Charge Production Ø 3 GHz RF Gun High efficiency photocathode comparison • Intermediate report done • Final report: reported to end of 2006 (no news from Twente. . ). • Photocathode preparation equipment construction – Under way, delays due to problems in refurbishing certain components, production of photocathodes should restart in November at CERN. • Photocathode 3 GHz high field R&D – Dark current measurements, thin fim adherence under high field etc. . – Will start after arrival of the RF Gun (December/January? ) » Milestone will probably slip by some months R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 2: Charge Production Ø Photocathodes for SC Cavity Photocathode preparation equipment ready (31/03/05) R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

FZR SRF Photogun – Cathode Preparation The photocathode preparation system was completely assembled and its function was tested. It contains two pairs of evaporators for Te and Cs, the holder and heater for the cathode with temperature measurement, a motor driven shutter, a measurement aperture for photo current, and two deposition rate monitors allowing co-evaporation, and is equipped with a 262 nm, 10 m. W laser system. The computer control system (electronics and software) is ready. At present, the system is disassembled and the parts are being cleaned. After that, the system will be assembled again in the clean room. R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 2: Charge Production Ø Photocathodes for SC Cavity Photocathode preparation equipment ready (31/03/05) • The new preparation equipment was installed and tested. At present it is being cleaned for installation in the clean room. Photocathodes tests • Will start when material ready. R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 2: Charge Production Ø Laser Driven Plasma source No fresh news from LOA …. . R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: LASER Ø Laser for the CTF 3 Photoinjector: All the milestones have shifted by ~6 months due to the late arrival of funding and long procurement delays due to specificity of the material. An important deliverable reached is the laser oscillator: Built by High. QLaser (Austria), it is the first of his kind with • rep rate of 1. 5 Ghz • rms pulse lenght < 10 ps • Jitter < 1 ps • Amplitude stability < 0. 2 % R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: Oscillator and preamplifier The results of the acceptance tests: The oscillator and preamplifier are now working to specification at RAL The additional preamplifier has delivered the required power The improved timing jitter seems to be due to low environmental noise at RAL Anomalous photodiode measurements at CERN have been resolved R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: Amplifier procurement Amplifier 1 assembly and testing will begin in September Amplifier 2 assembly and testing will begin in November R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: Updated layout of the system 350 cm Coding Thermal lensing compensation Table at RAL Beam size provided for 1 st amplifier Beam size provided for FHG High. Q amplifier 2 nd amplifier Breadboard Amplifier beam heights ~ 12 cm Table at CERN Laser beam to cathode Diagn. Delay line Beam size provided for SHG Faraday isolator Diagn. 150 cm Pockels cell(s) for generating 1. 5 us train 1 st amplifier Beam size provided for 2 nd amplifier Diagnostics FOM system Feedback stabilisation High. Q oscillator : alignment check camera : calibrated PD for power monitoring • Recent modifications include final layout of High. Q system, extra diagnostics and “inversion” of the overall scheme to improve stability of beam delivery to the accelerator vault • A timing and control system, compatible with the CERN architecture, has been specified R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: Time & Amplitude Structuring PULSE SLICING • Needs two large-aperture Pockels cells (single-pulse and 1. 54 ms train) to handle high average power after Amplifier 2 • Current design includes programmable corrector to reduce systematic pulse amplitude variations to <0. 1% RMS • System is commercially available AMPLITUDE STABILISATION • If the intrinsic amplitude noise is low then a low-retardance Pockels cell will be adequate, requiring low drive voltage compatible with fast electronic amplifiers • Performance will be dominated by the sensor and the feedback control electronics • Sensor and cell are commercially available but FC electronics need specialist design PULSE CODING • Requirement for a 7 MHz, multi-k. V, drive waveform with <300 ps switching time and better than 1% amplitude control makes a system based on a Pockels cell unviable • The alternative is a fibre-optic (FO) modulator system placed after the oscillator where the average power is low • The >10 d. B losses of an FO system will require more gain from the preamplifier • The FO system is commercially available and the preamplifier’s manufacturer can increase its gain, but this will involve some delay, best left to the end of the program R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: Fast pockels cell drivers New Fast Ionization Devices (FID) and Drift Step Recovery Diodes (DSRD) Customization of standard product. E. g: FPG-05 -10 S Output voltage at 50 Ohm 2 -5 k. V Pulse width at 90% of Umax 0. 3 -0. 5 ns Rise time <100 ps Fall time <500 ps Maximum repetition rate 10 k. Hz Timing stability (jitter) < 20 ps Maximum sync/output delay time 100 -150 ns Input trigger 5 V Power supply, DC 300 V Dimensions 100 x 50 x 40 mm R. Losito CERN-AB-ATB New devices developed by the Ioffe Physical-Technical Institute of Russia Academy of Science in St. Petersburg. They are based on a new physical phenomenon: the elctrone-hole plasma supergeneration in solid state. This permits to have high operating voltage up to 5 k. V and the turn-on time less than 1 ns. The DSRD are diodes characterized by fast voltage restoration that assures low commutation jitter, unlimited life time, repetition rate that can be as high as megahertz and opening times can be less than 1 ns with 100 A current. Care Steering Committee, Paris, 05/09/2005

WP 3, T 1: (LASER) Timescales and deliverables R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 2: Shaping of the UV laser pulse UV time profile measured using a multishot cross-correlator with 200 fs resolution. It is possible obtain rise-time < 1 ps and ripples < 30% R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 3, T 3 : Low rep rate synchronization tests at LNF High energy UV @ 10 Hz 2856 MHz cavity laser pulses On time scale of few minutes (enough to R. Losito CERN-AB-ATB adjust the RF) the phase jitter is within σRMS 0. 63 deg [0. 61 ps]. Further characterizations are foreseen. phase [deg] Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: FZR SRF Photogun Superconducting Nb cavities: The two cavities were delivered by ACCEL in March 2005. One is made of high-quality Nb RRR 300 for use in the gun, one of Nb RRR 40 for tests (instead of a Cu model, which additionally allows to check e-beam welding, warm tuning, and chemical treatment etc. ) R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: FZR SRF Photogun – RF Measurement and Tuning 1: Sensors-vertical position, 2: Sensors horizontal Pos. , 3: DC-Motor (bead pull drive), 4: Stepper motor (vertical pos. ), 5: Motor control box, 6: Sensor hardware, PC-controlled bead pull measuring device (principle) built at FZR in 2005. R. Losito CERN-AB-ATB 3 D-CAD-Model of the tuning machine used for warm tuning (to push and pull each cell to the right frequencies). The special cavity shape required to build such a machine at FZR. Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: FZR SRF Photogun – Warm Tuning Field profiles from bead pull measurements. Photograph of the cavity tuning machine with integrated bead pull measuring device. R. Losito CERN-AB-ATB Before chemical treatment, warm tuning of the cavities has been carried out in order to obtain the right frequency and the designed field profile (equal amplitudes in the three TESLA cells and 64% in the half-cell). Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: FZR SRF Photogun – Cathode Cooling System Cathode with heater Cooling body Liquid nitrogen reservoir The test of the cathode cooling system has been succeeded. In the SRF gun, the normal conducting cathode is inside the SC cavity. With the test was proofed whether the cathode heat load (from rf field) will be transported into the liquid N 2 cooler. It was found that the cooling system works well and only a small amount of the heat (some m. W) will be transferred to the SC cavity. The cathode cooling system mounted on the test bench flange. The rf heat load is simulated by an electrical heater (10 – 50 W). R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: FZR SRF Photogun – Project Status CAVITY: Two Nb cavities (Nb. RRR 300 + RRR 40) have been delivered. Rf-tests and warm tuning has been performed at FZR. Chemical treatment will now start at DESY. CRYOMODULE: Most of the main components (vacuum vessel, 80 K cryo-shield, magnetic shield, support frame, rf coupler, tuner, cathode cooler, cathode transfer system) have been delivered. Cathode cooler test has succeeded. The tuner test is under way. He transfer line is ordered. PHOTO CATHODES: The new preparation equipment was installed and tested. At present, it is being cleaned for installation in the clean room. LASER: The upgrade of the driver laser system is under way (MBI). DIAGNOSTICS: a diagnostics beam line is designed. The realization has started (BESSY). R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: 3 GHz RF GUN Ø WP 4 RF GUNS STATUS Ø 1 st RF Gun construction After many tries of the manufacturer to do a elliptical shape, a compromise was done: irises are done in 12 facets and it meets the specifications. ordered in the end of April, 4 months of delay, delivery in beginning of September Measurements and mechanical adjustments are planned for one month, delivery of the gun by the end of December if everything goes well Ø RF gun at LAL Laser was ordered to Opton Laser in July, delivery in 4 months Ø NEPAL room Shielding • Other Radio-protection study is under way to reduce the cost R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

WP 4, T 1: Spectrometer for e-beam Ø No News from LOA R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005

Conclusions Ø Work generally on track for CTF 3 photoinjector, Photoinjector at LAL, SC RF Gun and studies of pulse shaping in Frascati. Ø Due to holidays and to injury of Andrea, difficult to get information about Twente, INFN – Mi, Loa. Ø Should be addressed at the next collaboration meeting. R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005