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Linac4: Klystrons and Power Distribution

Nikolai Schwerg27/05/2010

1

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Starting Point: Re-use LEP RF equipment

Klystrons

– 20 LEP Klystrons (3 Manufacturers)

– together 50 years of operation left

– Re-tuning necessary

– Maximum power ?

Circulators

– 29 AFT-Circulators (different specifications)

– Reflected Power only 300 kW (for most circulators)

Constrains

– Phase and Amplitude for DTLs

– Space for PIMSs

– Similar design for all whole installation2

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Klystron-Gallery: LEP Klystrons

3

RFQDTLCCDTLPIMS

LEP Klystron2.8-MW-Klystron 2.8 MW-Klystron LEP Klystron

Amplifier

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Klystron-Gallery: Final Version

4

RFQDTLCCDTLPIMS

2.8 MW-Klystron

Amplifier

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Power Distribution Scheme – LEP Klystrons

5[Courtesy of J-P. Corso]

LEP Klystrons LEP Circulators Ferrite Loads Cavities

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6

Power Distribution Scheme – 2.8 MW Klystron

[Courtesy of J-P. Corso]0°

0°

180°0°

Δ Σ

2.8 MW Klystron

Folded Magic-Tee

LEP Circulators

Ferrite Loads Cavities

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Power Distribution Scheme – Alternative Waveguide Routing

7

[Courtesy of J-P. Corso]

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Power Distribution Scheme – Alternative 2.8 MW Circulator

AFT claims to be able to built a 2.8 MW circulator without SF6

Required:

– Offer – Price?

– Prototype for Testing

8

0°

0°

18

0°

0°

ΔΣ

2.8 MW Klystron

Magic-Tee

2.8 MW Circulator

Ferrite Load

Cavities

Ferrite Load

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Amplitude Phase

Power Splitter

Magic-Tee

Quantitative Approach

9

• Use S-Parameters: Ideal, e.g. Magic-Tee, Cavity, … Measured, e.g. LHC Circulator as function of T and I

• Solve for: Cavity input signal Reflection to Klystron

• Compare for all Working Points (thousands!)

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Test-Stand in Bat. 112

10

CCDTL/PIMS/DTL

Klystron Preparation

Klystrons

– Tuning of LEP Klystron

– Montage and Testing of HV-Box

– High Power Test

Circulators

– High Power Test

Cavities RP?

– Commissioning

Test of Full Installation

– Folded Magic-Tee

– Coupling between Circulators

– Higher Order Modes

Running by end of 2010

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Waveguide Connections

11[Courtesy of J-P. Corso]

• Determine: Waveguide length to Cavities Number and Type of Bends

• Derive Phase Difference

• 3-Post Phase Shifter Being built

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Ongoing Activities and Open Questions

Components:

– Performance of the Folded Magic-Tee

– Properties of 2.8 MW Circulator

RF Power Distribution Layout:

– Waveguide Length

– Phase Shifter

– Coupling of Circulators

– Cost and Risk Comparison

Testing:

– Building Test-Stand in Bat. 112

– Schedule for Cavity

– Components and Full Layout

12

Picture by MEGAindustries: Folded Magic-tee in WR650

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Thank you for your Attention

-- Discussion --

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Klystron Replacement

14As presented by Olivier Brunner

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Folded Magic-Tee

Specifications:

– Frequency: 352 MHz

– Insertion loss: < 0.1 dB

– Isolation between ports 1 and 2: > 37 dB

– Balance between ports 2 and 4: < 0.2 dB

– VSWR: 1.10:1 MAX (-26 dB)

– Power: Peak 2.8 MW Average 10 kW or 150 kW

These values are identical to the values of a standard magic-tee of the same supplier

15

Picture by MEGAindustries: Folded Magic-tee in WR650

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Design Constrains / Guidelines

Mechanical:

– Limited space in Klystron Hall (approx 3.50 m width)

RF:

– Minimum Reflection to Klystron

– Higher Order Mode Compensation

– Phase and Amplitude balance between both Cavities

– Prevention of Arcing

Installation:

– Using an identical Design for all Klystrons

– Considering two Variants: LEP Klystrons and new Klystrons

Operation:

– (Tuneablity)

– Accessibility of Loads and Circulators (Ferrite Breaking)

16

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Powering Schemes

17

160 MeV100 MeV50 MeV3 MeV

6 m 19 m 25 m 22 m3.7 m

RFQ DTL CCDTL PIMS

LEP Klystron 2.8-MW-Klystron2.8 MW-KlystronLEP Klystron

Amplifier

RFQ DTL CCDTL PIMS

2.8 MW-Klystron

Amplifier

Ph

ase

IP

ha

se I

I