Short-stay Study Abroad Program

Completion Report

DESY, Germany

2013/10/13 - 2013/11/24

Mathieu Omet

I

Contents

1 Motivation and Preparation 11.1 Relevance of Short-stay Study . . . . . . . . . . . . . . . . . . 11.2 Preparation before leaving Japan . . . . . . . . . . . . . . . . 1

2 Introduction of DESY 3

3 Study and Research during the Stay 5

4 Other Activities 7

5 Expenses 8

6 Language, Difficulties, and Advice for Future Applicants 96.1 Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96.2 Difficulties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96.3 Advice for Future Applicants . . . . . . . . . . . . . . . . . . 9

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Chapter 1

Motivation and Preparation

1.1 Relevance of Short-stay Study

The goal of the work during the doctoral course is performing research anddevelopments for the digital LLRF control of superconducting cavities in thescope of ILC. Learning about the hardware, firmware, and software used atCMTB, AMTF, FLASH, and the upcoming XFEL, performing experimentsat CMTB and AMTF, developing and testing algorithms as well as devel-oping concepts for FLASH and XFEL is exactly fulfilling this goal, since atthe moment FLASH is and XFEL will be the most to ILC similar existingaccelerator. With this the stay at DESY was a crucial step towards thecompletion of the doctoral course and the thesis.

1.2 Preparation before leaving Japan

Before the stay in a discussion between Shinichiro Michizono (SOKENDAI,KEK), Holger Schlarb (DESY), and Julien Branlard (DESY) it was decidedthat Julien Branlard would be the supervisor in the MSK group (MaschineStrahl Kontrolle, machine beam control) at DESY. In an e-mail correspon-dence the goals of the short time study were defined to be:

Get hands on experience at FLASH

Get hands on experience at AMTF

Get hands on experience at CMTB

Understand the klystron linearization implemented by Wojciech Ci-chalewski for comparison to the one implemented at Fermilab NML

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Improve klystron linearization implemented by Wojciech Cichalewski

Write klystron linearization package for µTCA.4 boards

Develop concepts for in the scope of klystron linearization (exceptionhandling, pulse to pulse klystron characterization)

Since the participant of the short-stay study abroad program is Germanno VISA and no preparation regarding the language was required. A roomat the DESY hostel as well as a flight were booked.

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Chapter 2

Introduction of DESY

The Deutsches Elektronen-Synchrotron (German Electron Synchrotron, DESY)is a national research center. The main site is located in the city of Hamburgin Germany. Figure 2.1 shows a map of it. DESY was founded in 1959 and isfinanced by the Federal Republic of Germany, the States of Germany, and theGerman Research Foundation, which is part of the Helmholtz Association.

Parking on the DESY premises is at your own risk. All city traffic regulations are valid and a speed limit of 30 km/h is allowed.Upon leaving the DESY premises random spot checks will be made at both gates. Please halt at the red traffic signal or the horn signal for inspection.

September 2012

Building Floor Room01 Firstfloor O1.02101e Groundfloor EG.52802b Basement 011b03 Thirdfloor 32305 Groundfloor 00507 Thirdfloor 30909a Firstfloor 10610 Firstfloor 11611 Basement 00625b Groundfloor 02925c Groundfloor 00425f Groundfloor 06328c Groundfloor 025a30 Secondfloor 223b30b Firstfloor 165b34 Groundfloor 00647c Firstfloor L112a50 Seventhfloor 73355 Groundfloor 00772 Groundfloor EG.00572 Secondfloor O2,203

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Laboratory1Directorate

Press and public relations Company medical officer

Library Laboratory2a,Theory

ComputerCentre,UCOLaboratory

Laboratory3Caretaker

StoragebuildingGasstation

Auditorium,entrancebuilding6Administrationbuilding,Guest services

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Cafeteria, BankBistro

WorkshopPurchasingdepartment

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Gate lodge Notkestraße (maingate)

Gate lodge Luruper Chaussee (sidegate)

LiquifiyingplantGascylinderbuilding

HeliumcontainerbuildingVacuumlaboratory

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10kVmainstationCoolingplantDESYII

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LaboratoryoftheUniversitiesof HamburgandLübeck

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EMBLHASYLABlaboratory1,MPGHASYLABX-raywigglerhall,

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TTF/experimentalhallIIICryogenichallFLASHtunnel

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StorageringDORIS/experimentalhallIVDORISsupplyinghallAcceleratoroperationbuildingPowerstationAcceleratorcomponentsbuildingGuest house 2KindergartenGuest house 3Trainingareaphysik.begreifen@desy.deSafetygroup/CommunicationengineeringPreparationhall,experimentalhallVAssemblyhallStoragebuildingPETRAhallsSOPETRAhallsSPETRAhallsSWPETRAhallWPETRAhallsNWPETRAhallsNPowerstation,coolingplanPETRAhallsNOPETRAIIIexperimentalhallPETRAIIIcoolingplantPETRAhallsO/EMBLOfficebuildingHERAhallwestRefrigerationtechnologyhallMagnetmeasurementhallProtonvacuumbuilding

UniversityHamburgAuditoriumInstituteofexperimentalphysicsPreparationbuildingWorkshopTheoryInstituteofexperimentalphysicsInstituteofexperimentalphysicsInstituteoflaserphysics

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ZentrumfürOptischeQuanten- technologie(ZOQ)CFEL

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HERAhallnorthHERAhalleastHERAhallsouthEuropeanXFELProjectmanagementagency PT-DESY

Off-site buildings:

Figure 2.1: Map of DESY.

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The main purpose of DESY is scientific fundamental research with thefocus on:

Development, construction, and operation of particle accelerators

Particle physics

High energy physics

Research in the fields of physics, chemistry, biology, geology, and medicineusing photos

To this end several large scale facilities were and are operated, such asDESY, DESY II, DESY III, DORIS, DORIS II, DORIS III, PETRA, PETRAII, PETRA III, HERA, LINAC I, LINAC, II, LINAC III, FLASH, and theupcoming FLASH II. Further projects DESY is involved are the CFEL, theXFEL (under construction at DESY), and the ILC.The number of employees at DESY is approximately 2000, including about650 scientists working in the fields of accelerator operation, research anddevelopment as well as more than 700 diploma students, doctoral candidates,and postdocs as young scientists. Each year more than 3000 scientists fromover 40 countries are visiting in order to research.

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Chapter 3

Study and Research during theStay

In total two shifts at the FLASH main control room were joined. The firstwas devoted to LLRF studies and the second to SASE tuning. This gavea good insight about the operation of FLASH, the control system DOOCS,and the GUI JDDD.

The 5 MW klystron of the Accelerator Module Test Facility (AMTF)stand 3 was characterized in matters of output amplitude and phase usingan open loop feedforward scan. This data was recorded for several reasons.With this data the phase linearization performance of the formerly imple-mented klystron linearization was better understood. Furthermore this setof data can be used as the basis of a possible FPGA-based klystron simulator.Beside the klystron output characteristic in matters of amplitude and phasealso the performance of the used vector modulator was analyzed. In generalexperience in klystron operation was deepened.

The 10 MW klystron at the Cryo Module Test Bench (CMTB) was char-acterized in matters of output powers at different high voltage settings usingan open loop feedforward scans. No signal for measuring the output ampli-tude and phase was available. Since the µTCA.4 system was not operationalat CMTB the predecessor the VME system was used. This gave a good in-sight about the GUI DDD. During the measurements crosstalk in the VMEsystem (in the down converter) towards the cavity probe signals was found.

The formerly at DESY implemented klystron linearization by WojciechCichalewski was analyzed and compared to the one the participant of theshort-stay study abroad program implemented earlier that year at Fermilab

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NML. Since the FPGA firmware implementation consists mainly of a lookuptable and multiplications, the actual know-how is located in the MATLABscript for the generation of the lookup table. This script was analyzed and away for improvements regarding the amplitude and phase linearization per-formance was found. Based on this a new MATLAB script for the creationof the lookup tables was created. Even no access to the FGPA firmwarewas granted in order to protect of DESY’s intellectual property, a klystronlinearization algorithm for the uTCA.4 board was programmed. In a iSimsimulation of the klystron linearization package within a test bench a proof ofconcept was shown. Furthermore by successfully uploading the firmware toan FPGA it was demonstrated that the code quality was already sufficient.The final implementation on the µTCA.4 hardware can only be performedby DESY personal.Depending on the firmware used this klystron linearization package can alsobe used for realizing an FPGA-based klystron simulator.

Strategies for exception handling especially in the scope of the klystronlinearization were developed. Those cover what possibly can go wrong, howto detect it, how to prevent it, and how to recover from it.

Strategies for pulse to pulse as well as for intra-pulse klystron charac-terization methods were suggested. These would allow to characterize theklystron during operation. By this the until now required downtime for theklystron characterization could be omitted. The lookup tables can be re-freshed during operation in an automated way, which is especially importantwhen the working point (e.g. high voltage of klystron) is changed.

In the scope of the weekly DESY LLRF seminar a talk with the title“Development and Test of Digital LLRF Control Procedures and TechniquesTowards ILC” was given.

In the scope of a weekly LLRF meeting in the last week of the short-staystudy a presentation with the title ”Concepts, Developments, and Tests inthe Scope of Klystron Linearization” summarizing the work at DESY washeld.

Tours around the facilities of AMTF, CMTB, and the European XFELwere joined.

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Chapter 4

Other Activities

Beside the work at DESY the Helmholtz-Center Berlin in Berlin, Germanywas visited for one day in order to give a seminar talk with the title “Entwick-lungen und Tests von digitalen Low Level RF (LLRF) Regelungstechnikenund Prozeduren im Rahmen des International Linear Colliders (ILC) - De-velopment and Test of Digital LLRF Control Procedures and TechniquesTowards ILC”, to get in touch for a possible future position, as well as tojoin a guided tours at the electron storage ring BESSY II as well as at theheavy machine hall, in which a vertical cryo test stand for up to two 9-cellTESLA-type cavities and an undulator test stand are located.

Furthermore also the GSI Helmholtz Centre for Heavy Ion Research inDarmstadt, Germany was visited for one day in order to give a seminar talkwith the title “Development and Test of Digital LLRF Control Proceduresand Techniques Towards ILC”, to get in touch for a possible future position,as well as to learn about the recent hardware and FPGA firmware develop-ments for cavity control in the scope of FAIR at the Ring RF group.

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Chapter 5

Expenses

Tabel 5.1 lists all expenses for travel and accommodation actually spent.Sokendai covered the part of the expenses as described in the regulations forthis program.

Table 5.1: Expenses of short-stay study at DESY.Purpose Amount CurrencyTransportation to and from airport in Japan 5 680 YenFlight from Narita, Japan Narita to Hamburg, 231 400 YenGermany and backTransportation from and to airport in Hamburg 7.70 EuroDESY Hostel for 9 days 252.00 EuroRoom in private apartment for 34 days 584.67 EuroTransportation between room and DESY 72.20 Euro

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Chapter 6

Language, Difficulties, andAdvice for Future Applicants

6.1 Language

During work the languages German and English are used. Since the partici-pant of the short-stay study abroad program is German this was no problem.Due to large number of mostly Polish colleagues at the MSK group all meet-ings are held in English.

6.2 Difficulties

No actual difficulties occurred.

6.3 Advice for Future Applicants

The DESY hostel offers a room only for a period of time of up four weeks.After this one has to stay outside. DESY offers a list of places, where onecan rent a room (mostly in private apartments). This is much cheaper thanthe DESY hostel as well as hotels. If it is planned to stay longer than fourweeks at DESY a request for being put on the list for renting a room shouldbe done (at best several weeks) before the trip.In Germany all shops are closed on Sunday and on holidays. Only somerestaurants are open. One has to keep this in mind and plan ahead.Usually water with gas is drunk in Germany. Water without gas is called”still” or ”stilles Wasser”.

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Motivation and PreparationRelevance of Short-stay StudyPreparation before leaving Japan

Introduction of DESYStudy and Research during the StayOther ActivitiesExpensesLanguage, Difficulties, and Advice for Future ApplicantsLanguageDifficultiesAdvice for Future Applicants