Update on X Band Klystron Modulator Installation

1. Update on X Band Klystron Modulator Installation

2. Observations on certain issuesraised with Scandinova during recent workshop at PSI • Technical Specifications • Contractual issues, that were in the specification accepted by Scandinova that have not been met, but are in process of being resolved • Quality Control • Some small issues • Adaptability of K2 basic design for different types of klystron • Misinterpretation and ergonomics • Future technical specifications will need to be clearer and discussed before future contracts • Miscellaneous • Summary of these issues • Plan of action to get modulator and klystron running

3. Technical SpecificationsThe following points were stated in the technical specification that SN stated the would meet in the call for tender Rise / fall time of HV pulse, pulse width 2.3uS half height Scandinova accepted this specification and was one of the key elements to take award the contract. SN think now this is very technical challenging and may not arrive at this value. We have asked for a interlock to be integrated on the maximum pulse width. The fact that the pulse width during the tests at SLAC were larger is not an issue as a shorter pulse width will give a longer life expectancy for the tube

4. Technical Specifications(continued) Interlock on body interception, delta T and Flow rate of body needed No measurement possibility for either delta T or body water flow in modulator, this issue is being resolved by Scandinova and will be implemented on next visit

5. Quality control • Water valve of solenoid circuit missing • Problem resolved by CERN • Flow meter interlock missing • Will be resolved by Scandinova on next visit • Leaking joints on oil pump • Solution to be implemented by Scandinova on next visit • Some small pieces of burred metal found in tank when draining oil after dummy load tests, • Don't know where these came from was it in pulse Tx (cleanliness) • Is there a tank deformation when klystron was put onto lid? • View ports were not flush to tank when we tried to put them back on after installing klystron, SN sais was like this in factor (this should have been resolved or at least have been notified to CEA) Deformation measurement will be made next time klystron is lifted from tank

6. Misinterpretation and Ergonomics • Air tightness of tank was specified in specification • Not in K2 baseline design but XL5 tube different to Thales and higher oil level needed to cover tube ceramic • This means filling tank up to limit of lid, when oil expands and it seeps out of lid • Problem being resolved at the moment (details on later slide) • Radiation shielding • SN provided lead shielding but was impossible to manipulate connections to klystron therefore not installed, maybe future tanks should be made bigger to implement shielding on walls of tank • Lead shielding being modified at CERN, should be finished next week

7. Miscellaneous • We are worried about the non direct measurements of voltage and current of the klystron i.e. calibration • Current transformer on low side of pulse Tx, not a true indication of pulse shape in klystron due to stray capacitance • Voltage divider not directly on cathode of klystron (calibration) • We also had a welding point on the water distribution that was not good, this was fixed at CERN • Connectivity from Tx to klystron. We were not happy with the push in connectors decided to screw cables to sockets .. But the nuts were non metric ! Problem solved by drilling into the existing screws and tapping to M5

8. Klystron installation in modulator Oil was removed from tank after dummy load tests some very small metal pieces were noticed at the bottom of The tank. This worried our SLAC colleaguse

9. Summary • We have only done a sing pulse at 40kV into klystron now waiting for some issues (as mentioned above) to be resolved before continuing the commissioning • For future modulators based on K2 model some adaptability may be needed from SN • e.g. Bigger tank to allow for shielding and capacitive voltage divider directly on cathode • i.e. bigger footprint for modulator • Clearer more precise specification needs to be made by purchaser clearly identifying what is required and what deviates from the basic K2 design

10. Plan of action All water connections have been modified including pipe work to allow CERN standard Pt100 temperature probes for body, collector and window (non compatibility between European and USA standards) Perspex screen installed to protect solenoid terminals Temporary cover for viewport with visualisation of oil level

11. Plan of action Before pulsing the lid of the tank on the transformer side must be raised by 4 cm to assure that the oil covers all klystron gun piece designed and manufactured delivered to CERN today Realignment of girder for crane will be done tomorrow (offset 5cm) company was not available until now due to LHC shutdown Installation of the shim plate to be done sometime in the next 2 weeks Dependant on how well the start up of CTF3 goes (manpower) and the availability of TS dep to retest crane

13. Plan of action • Mid February, Scandinova will be present to continue commissioning of modulator • Installation of interlock for body power • Interlock testing • Initial adjustment of flat top of voltage pulse • RP measurements of installation • End February • Start RF conditioning of existing network • 1,2, 3 weeks??? • Testing of RF interlocks etc

14. Plan of action • March • Dismount waveguides • Dismount klystron • Lift pulse transformer to install final capacitive adjustment for flattop • Reinstall klystron connect to new waveguide network down to CTF2 (with or without pulse compressor?) • Bake-out • RF conditioning

15. Summary • Optimistic estimate • Installation of first x band structure some tme in May • Conditional on many things