RF Power R&D David Wildman May10, 2005 Slides “borrowed” from: G. W. Foster, A. Moretti, D. Sun,...

RF Power R&D

David Wildman

May10 , 2005

Slides “borrowed” from:G. W. Foster, A. Moretti, D. Sun, I. Terechkine, D.Wildman,& D. Wolff

May 10, 2005wildman - AAC Meeting 2Fermilab

Outline

• System Overview • 325 MHz Klystron• Modulator for Klystron• I/Q Modulators• Phase Shifters (3 Types)• Conclusions

325 MHz RF System

Pulse Transformer& Oil Tank

IGBT Switch & Bouncer

CAP

BANK

10 kV110 kVCharging

Supply

300kW

MODULATOR: FNAL/TTF Reconfigurable for 1,2 or 3 msec beam pulse

SingleJPARC Klystron325MHz

3 MW

WR2300 Distribution Waveguide

TO

SH

IBA

E

374

0A

I

Q

M

I

Q

M

I

Q

M

I

Q

M

R F Q

I

Q

M

Cables inTunnel

Fast Ferrite Isolated I/Q Modulators

RF Couplers

S

I

Q

M

S

I

Q

M

R

I

Q

M

S

I

Q

M

S

I

Q

M

R

I

Q

M

600kW 40 kWmax.

D

I

Q

M

S

I

Q

M

R

I

Q

M

D

I

Q

M

S

I

Q

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R

I

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120 kWmax.

10kV

H-

Room TemperatureCopper Cavities (23)

Radio FrequencyQuadrupole

Cryomodule #1 Single-Spoke

Resonators (16)

Cryomodules #2-3 Double-Spoke

Resonators (28 tot.)

5 kW..

MEBTRT-TSR

… 60 kWmax.

110 MeV


Tube is designed for particle Accelerators. Tube tunable to 325 MHz:

Tube is in production for J-Parc; 17 tubes have recently been delivered to J-Parc.

Power Output = 3.0 MW Gain = 50 dB Efficiency = 55 %

Duty Factor = 2.6%

Toshiba E374A High Power Amplifier Klystron

Toshiba factory test at 1.5 ms4.5 ms test done at Fermilab


Klystron Status

• Negotiations are in the final stages for the purchase of one 325 MHz klystron from Toshiba.

• Toshiba is quoting a delivery date of March 2006.


Proton Driver Modulator Requirements

• Purpose: Provide the pulsed power needed for Klystron operation

• Specifications– Pulse width: 4.5 ms

– Pulse Voltage: 120 kV

– Pulse Current: 140 amps

– Repetition rate: 2.5 Hz

– Average Power 225 kW

– Support operation for both MBK and TOSHIBA

325 MHz klystrons

– Allow cost effective redeployment to 1.5ms operation


Fermi-built TESLA Modulator

• 3 Modulators built in 1990s • Specifications (PD)

– Pulse width: 1.7 ms (4.5)

– Pulse Voltage: 120 kV

– Pulse Current: 130 amps (140)

– Repetition rate: 10 Hz (2.5)

– Average Power 300 kW (225)

• First modulator has run for 25,000 hours (since 1993)

• Second and third modulators have run for 18,000 hours each (since 1996)


Modifications to Fermi Modulator for PD

• Changes needed to meet spec– 3x larger cap bank

– 3x larger “Bouncer” Circuit

– 3x larger pulse transformer

• Changes to reduce cost– Traction type capacitors

Used extensively in Europe and SNS modulators

– 1.6kV IGBTs replace with 3.3kV units

(SLAC collaboration)

– Back-up switch plus fast crowbar replaced with redundant, fail-safe switch.

– Updated controls


4.5 ms Modulator Simplified Diagram


Modulator Construction Schedule

• EE Support is in the process of building 2 modulators for SMTF.

• Requisitions for capacitors and pulse transformers have been awarded.

• The first unit should be finished by the end of this year.


CAUTION

We are now going from one type of modulator to another!


I/Q modulator box (stripline structure)

Box size: 24” x 20”


325 MHz I/Q Modulator Specifications

• Power (peak/average, duty factor 1.5%)– 40 kW/ 600 W

– 150-200 kW/ 2.25-3 kW

– 650 kW/9.75 kW (1 feed option for RFQ)

• Tuning Range– Phase: +/- 45 degree

– Amplitude: +/- 1.5 dB

• Phase Tuner Slew Rate– 1 degree/1sec


325 MHz I/Q Modulator R&D Program

• Determine what type of rf structure (stripline, coaxial or waveguide) should be used for each power level.

• Demonstrate fast tuning capability.• Solve potential technical issues: rf breakdown,

cooling, and ferrite stability.• Simplify assembly and cost reduction.• Goal: to be ready when klystron arrives.


325 MHz I/Q Modulator

• The Plan– Low power level (40 kW)

• Use stripline structure to build a joined hybrid and circulator into one box with 4 coaxial ports.

• Power test this device with coaxial phase shifter at Argonne.

– Medium power (150 kW)• Power test a coaxial structure

– High power level (650 kW)• This is a special case.

• First evaluate the number of rf feeds for RFQ to determine the power level

• Then choose structure: either waveguide (magic tee) or coax


325 MHz I/Q Modulator

• Status– Low power level (40 kW)

– Preliminary design of circulator and hybrid (circuit simulation and 3D E-M simulation) is done.

– A prototype circulator using available ferrite disks is built and measured: achieved low insertion loss (-0.06 dB) and high isolation (-27 dB)

– Received new ferrite disks to adjust the frequency of the circulator.


Prototype Circulator


Approaching the Phase Shifter Problem

1. Develop and test waveguide-based phase shifter;

2. Test the coaxial phase shifter available at FNAL

3. Work with a vendor to build an I/Q modulator


Amplitude and Phase (IQ) Modulator

cos0 jeEE

sin0 )2/(jeEE

= (1+2)/2

= (2-1)/2

1 2

Yttrium Iron Garnet

Ferrite Shifters can be built based on:

• Coaxial line,

• Strip-line,

• Waveguide


Performance Requirements

Frequency: 1300 MHz ± 1 MHz

Phase Change: ± 45°

RF Power Ratings: 550 kW Peak, 1.5 ms, 10 Hz

550 kW Peak, 4.5 ms, 3.3 Hz

Insertion Loss: less than 0.2 dB

Response time: time constant ~ 30 s

Flange: WR-650


Waveguide Phase Shifter

Main design issues:

• High power operation

• Heat management

• Tuning range

• Response time

CoreCoil


Phase Shifter Mockup Low Level RF Measurements

Results of the low level RF measurements are in a good agreement with modeling (HFSS)


High Power Test

A0 1300 MHz Klystron

T = 250 µsec

F = 5 Hz

Existing A0 interface was used for testing


High Power Test at 1300 MHz

Two methods of phase measurements:

1. Oscilloscope measurements

2. Using available IQ modulator

Available phase zone is limited by sparking that develops near the resonance frequencies

Max Power - 2000 kW (req. 600 kW)

Phase shift - ~ 80° (req. 90° )

SF6 added


Why Choose a Coaxial Design?

• Usable over a wide frequency range– Unlike waveguide has no cutoff frequency

– Same shifter could be used at both 325 MHz and1300 MHz

• Easy to understand- TEM modes • Compact : smaller size is generally good but

leads to higher fields• Modified 3 1/8” coax line, fully filled with

aluminum doped yttrium-iron garnet


Phase Shift & Transmission

• S11 measurement of 10 TCI cores

Transmission @ 325 MHzPhase Shift @ 325 MHz


Fast Response of Shifter @325 MHz - 5 cores

Bias Current100A/Div

Phase Shift~15 Deg/Div


High Power Test @ 1300 MHz


Phase Shift During 352MHz, 100kW Pulse

Phase Shiftfrom mixer

Forward Power


Coaxial Phase Shifter

•Coax design is preferred at 325MHz• In-house design tested to 660kW at 1300 MHz• Tested at 300 kW at Argonne with APS 352MHz Klystron • Fast coil and flux return should respond in ~50us


Advanced Ferrite Technology GmbH (AFT)

Products:

High Power CirculatorsFast Ferrite TunerFast High Power Phase ShifterHybrid Tuner SystemsFerrite MaterialElectrical Power Suppliesfor high power inductive loads

The IQ modulator from AFT is expected in May:

1 Magic Tee; 1 straight waveguide section; 2 waveguide - coax transition; 2 FFT´s directly connecting to the transition; 1 control unit for setting phase and amplitude and feedback loop; 1 dual directional coupler for amplitude control; 1 arc detection system.

Power supply will be provided by FNAL


Phase Shifter Conclusions

1. The prototype of a waveguide-based, 1.3 GHz phase shifter shows excellent maximal power and acceptable phase shift performance.

2. Coaxial phase shifter meets peak power and phase shift requirements both at 1300 MHz and 325 MHz.

3. Commercial prototype of an I/Q modulator due this month.

4. Average power testing, reaction time testing, and IQ modulator modeling should be the next steps of the R&D


General Conclusions

• We’ve made a good start on our R&D program

• We still have a lot of work to do before the Toshiba klystron arrives next March.

RF Power R&D David Wildman May10, 2005 Slides “borrowed” from: G. W. Foster, A. Moretti, D. Sun,...

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Transcript of RF Power R&D David Wildman May10, 2005 Slides “borrowed” from: G. W. Foster, A. Moretti, D. Sun,...