m. a. clarke-gaytherral/astec/hippi spg development beam chopper r & d for next generation high...

M. A. Clarke-Gayther RAL/ASTeC/HIPPI

SPG development

Beam Chopper R & D for

Next GenerationHigh Power Proton Drivers

Michael. A. Clarke-Gayther

RAL / ASTeC / HIPPI


‘Fast-Slow’ Chopping at RAL

HIPPI WP4: The RAL† Fast Beam Chopper Development Programme Progress Report for the period: January 2004 – June 2005

M. A. Clarke-Gayther †

† CCLRC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK

EU contract number RII3-CT-2003-506395 CARE/HIPPI Document-2005-008



Chopper 1 (fast transition)

Chopper 2 / Beam dump(slower transition)

BEAM

Fast and slowchoppermodules


FPG development

M. A. Clarke-Gayther RAL/ASTeC/HIPPI4

Phase 2 FPG systemDual polarity @ 1.4 kV max.

9 x Pulse generator cards

High peak power loadsControl and interface

Combiner


Power supply




FPG development

Pulse Parameter ESS Requirement

Measured Compliancy Comment

Amplitude (kV into 50 Ohms) ± 2.2 ± 1.5 No Scalable

Transition time (ns) ≤ 2.0 Trise = 1.8, Tfall = 1.2 Yes 10 – 90 %

Duration (ns) 10 - 15 10 - 15 Yes FWHM

Droop (%) 2.0 in 10 ns 1.9 in 10 ns Yes F3dB ~ 300 kHz

Repetition frequency (MHz) 2.4 2.4 Yes

Burst duration (ms) 1.5 1.5 Yes

Burst repetition frequency (Hz) 50 50 Yes Duty cycle ~ 0.27 %

Post pulse aberration (%) ± 2 ± 5 No Reducible

Timing stability (ps over 1 hour) ± 100 ± 50 Yes Peak to Peak

Burst amplitude stability (%) + 10, - 5 + 5, - 3 Yes

Measured performance parameters for the Phase 2 FPG system


FPG development

Time & amplitude dependent FPG waveform analysis / 324 MHz FETS scheme


FPG development

† Assumes 4 kV SPG with ~ 9 ns transition time (10 – 90 %)†† Assumes 8 kV SPG with ~ 12 ns transition time (10 – 90%)

FPG duty cycle and LF droop for the ESS and FETS schemes


FPG development

FPG duty cycle droop compensation


FPG development


I.S. RAMPING (100 % CHOPPING) 30 % CHOPPINGOFF


FPG development


CH BEAMI.S. RAMPING CH BEAM CH BEAM CH BEAM CH

805 ns


FPG development

0.8 m

0.28 m

SPG Module

SPG prototype system / Modular construction


SPG development

Pulse Parameter ESS Requirement

Measured Compliancy Comment

Amplitude (kV into RLC load) ± 6.0 ± 6.0 Yes ± 8 kV rated

Transition time (ns) ~ 12.0 Trise ~ 13, Tfall ~ 12 Yes 10 – 90 %

Duration (μs) 0.2 – 100 0.2 – 100 Yes FWHM

Droop (%) 0 0 Yes DC coupled

Repetition frequency (MHz) 1.2 1.2 (≤ 6 μs burst) Limited Burst limitation

Burst duration @ 1.2 MHz 1.5 ms ≤ 6 μs No Burst limitation

Burst duration @ 0.1 MHz PRF - ≤ 10 ms - PRF limitation

Burst repetition frequency (Hz) 50 50 Yes Duty cycle ~ 0.27 %

Post pulse aberration (%) ± 2 ≤ ± 2 Yes

Timing stability (ns over 1 hour) ± 0.5 ± 0.4 Yes Peak to Peak

Burst amplitude stability (%) + 10, - 5 < + 10, -5 Limited @ 0.1 MHz PRF

Measured performance parameters for the ‘Breadboard’ SPG system


SPG development

SPG prototype system designed and part constructed• Pre - prototype measurements show PRF limitation• Prototype tests will explore switch limitations

Preparation of detailed specification for new HV switch• FETS schemes A & B reduce voltage requirement

Identification of candidate HV switch manufacturers• Behlke (Germany), DEI (USA), Kentech (UK)

Distribute SPG specification to manufacturers • Prepare to modify existing SPG module design

Status


Slow-wave structure development

Helical structure B / Construction

BEAM

PULSE OUT

PULSE IN

BEAM

PULSE OUT

PULSE IN

BEAM

BEAM

Helical structure B with L - C trimmers and adjustable delay

AdjustableL-C trimmer

Adjust cablelengths to change delay



BEAM BEAM

Helical structure C with L - C trimmers

Quadrupole borediameter



Re-design for 3 MeV operation• Simulation using CST Microwave Studio code• Implications of reduced delay to be explored• Integrate adjustable L-C trimmers into new design

Manufacture pre-prototype modules• Bench test using TDR & TDT techniques

Planned activity



Summary

Three candidate chopping schemes for RAL FETS• Schemes A & B ready for first engineering analysis

FPG can meet ESS and RAL FETS requirements• Duty cycle droop compensation scheme to be tested

SPG prototype system designed and part constructed• Pre - prototype measurements show PRF limitation

Slow – wave structure engineering concepts refined• L – C impedance trimming and adjustable delay

m. a. clarke-gaytherral/astec/hippi spg development beam chopper r & d for next generation high...

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