Update on X Band Klystron Modulator Installation

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

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 heightScandinova 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

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

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

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

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

Klystron installation in modulator

Oil was removed fromtank after dummy load testssome very small metal pieceswere noticed at the bottom ofThe tank. This worried our SLAC colleaguse

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

Plan of actionAll water connections have been modifiedincluding pipe work to allow CERN standard Pt100 temperature probes for body, collectorand window (non compatibility between European and USA standards)

Perspex screen installed to protect solenoidterminals

Temporary cover for viewport with visualisation of oil level

Plan of actionBefore pulsing the lid of the tank on thetransformer side must be raised by 4 cmto assure that the oil covers all klystron gunpiece designed and manufactureddelivered to CERN today

Realignment of girder for crane will be donetomorrow (offset 5cm)company was not available until now due to LHCshutdown

Installation of the shim plate to be done sometimein the next 2 weeksDependant on how well the start up of CTF3 goes(manpower) and the availability of TS dep to retest crane

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

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

Summary

• Optimistic estimate• Installation of first x band structure some tme

in May • Conditional on many things