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EMMA RF System Alan Wheelhouse, ASTeC, Daresbury Laboratory

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EMMA RF System Alan Wheelhouse, ASTeC, Daresbury Laboratory. Content. EMMA RF System Overview Specification RF System Progress RF Cavity High Power RF System Waveguide Distribution System LLRF System Cabling & Connections Plan. RF System Overview. RF Cavities.

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Presentation Transcript
  • EMMA RF System Overview
    • Specification
  • RF System Progress
    • RF Cavity
    • High Power RF System
    • Waveguide Distribution System
    • LLRF System
    • Cabling & Connections
  • Plan

Commissioning Workshop Alan Wheelhouse

rf system overview
RF System Overview

RF Cavities

High Power RF Amplifier System

Waveguide Distribution System

Commissioning Workshop Alan Wheelhouse

rf cavity
RF Cavity

Commissioning Workshop Alan Wheelhouse

cavity design specification
Cavity Design & Specification

* LLRF + Distribution

Commissioning Workshop Alan Wheelhouse

rf cavity progress
RF Cavity Progress

Input Coupler construction

(Times Microwave)

  • All 20 cavities delivered
    • Delays due feed-through delivery from Times Microwave
  • 14 cavities tested
    • Tests on-going
  • Tuners sticking
    • Sheered copper spring
    • Spring replaced with lighter force copper spring
    • Silver plated
  • Q0≈20000 achieved
  • Four cavities successfully conditioned
    • One conditioned to 10kW
    • Three conditioned to 5kW

Cavity construction

Tuning range 0- 25 mm

Commissioning Workshop Alan Wheelhouse

rf cavity evaluation
RF Cavity Evaluation
  • Procedure defined
  • 14 cavities tested
    • Rest being tested presently
  • Pick probe altered on a number of cavities
    • Optimisation for 40 dB transmission
  • QL≈10,000 achieved

Commissioning Workshop Alan Wheelhouse

high power rf amplifier system

Commissioning Workshop Alan Wheelhouse

cpi vil409 hprf system
CPI VIL409 HPRF System
  • 45kV switch mode power supply
  • Charging capacitor
  • CPI IOT VKL-9130B
    • Tested to 100kW
    • 5.5MHz bandwidth
  • Bruker solid state amplifier
    • Tested to 1.8kW (linear)
  • WR650 waveguide output
    • Via a circulator


Solid State Amplifier



Charging Capacitor


Commissioning Workshop Alan Wheelhouse

factory acceptance tests
Factory Acceptance Tests
  • Factory acceptance tests completed Sept 09
  • Power requirements met across the frequency band
    • 90kW at waveguide
    • Up to 96kW from IOT
    • Efficiency > 50%
    • Gain typically > 20dB
  • HV pulse droop - 1.25kV
  • HV ripple 150V @ 44kV
    • 0.34% (Spec ±0.5%)
  • Grid voltage ripple 0.4V @ 95V
    • 0.42% (Spec ±1%)
  • X-ray levels 10µSv/h seen at the IOT (Spec 2.5µSv/h)
  • Issue with parameters reading values during off periods!



Commissioning Workshop Alan Wheelhouse

trip response times
Trip Response Times
  • Trip response time and repeatability issue
  • Improvements made to the trip circuit
  • Repeatable trip response times of 80µs achieved
  • Wire crowbar test successfully performed at 40kV
    • 6” AWG32 wire with enamel
    • Stored energy < 18J (Spec 15J)

1 TTL pulse from PIN diode

2 Fault

3 RF pulse

4 Nesting pulse to SS amp

Commissioning Workshop Alan Wheelhouse

site acceptance tests
Site Acceptance Tests
  • Delivered 23rd September 2009
  • Installation and site acceptance completed 2nd October 2009
    • Power level and frequency responses checked
    • Issue with EPICS interface
    • Now resolved
    • Temporary water fittings used from ALICE
    • Operations manual being prepared
    • Draft operations manual supplied 23rd November 2009

Commissioning Workshop Alan Wheelhouse

harmonic and noise tests
Harmonic and Noise Tests
  • Input tuned for 1.29875GHz
  • X-ray levels at 90kW level
    • 11.2µSv/h seen at the IOT for 1.2960GHz
    • 9.5Sv/h seen at the IOT for 1.3000GHz
    • 13µSv/h seen at the IOT for 1.3015GHz
  • 0.3µSv/h at the cubicle panel
  • Warning labels to be added to panels

Commissioning Workshop Alan Wheelhouse

epics interface
EPICS Interface
  • EPICS interface working
  • Labview program modified so that values read zero when off
  • EPICS controls layout being designed

EPICS Dummy Screen

Commissioning Workshop Alan Wheelhouse

waveguide distribution system

Commissioning Workshop Alan Wheelhouse

waveguide distribution system1
Waveguide Distribution System

Commissioning Workshop Alan Wheelhouse

test set up
Test Set-Up


Mega hybrid splitter

Output cable

Bridge section

Balance load


Transition / Phase shifter


Commissioning Workshop Alan Wheelhouse

test set up 2
Test Set-Up (2)

Cable support bracket

End launch transition

to 7/8 IEC

Phase shifter with McLennan motor

Balance load

Load tuners (isolation trimmers)

E plane tuners

Angled flange

Floor support bracket

Directional coupler

Adjustable shorting bars

Commissioning Workshop Alan Wheelhouse

flange gasket assembly
Flange & Gasket Assembly

Angled flange


Commissioning Workshop Alan Wheelhouse

phase shifter characteristics
Phase Shifter Characteristics
  • Phase shifter resolution
    • 0.1° = 0.01mm
  • Full range = 196°
    • Spec : 180°
  • As the phase shifter goes further in it approaches the waveguide cut-off

Commissioning Workshop Alan Wheelhouse

input return loss
Input Return Loss

All output cables were terminated in precision 50Ω loads

Input return loss <30dB



Commissioning Workshop Alan Wheelhouse

output responses
Output Responses

Single input tests

The 3 dB amplitude difference due to the hybrid splitter

All cables and their phase shifters set to produce a co-phase output at the lowest operating frequency

  • The reference port is 1/2 LHT
    • Midway phase value after cable trimming
  • Phase setting, over full bandwidth > 180°



Commissioning Workshop Alan Wheelhouse

differential output phase
Differential Output Phase

Phase shifters set to 0° and 180°

Measurements performed with respect to the reference port

Demonstrates that full phase shift control can be achieved

0° setting

180° setting

Commissioning Workshop Alan Wheelhouse

  • Sample of isolation between output ports
  • Isolation between ports:
    • > 42 dB (Typically 50 dB)
    • Optimised using balance load tuners
  • Worst case path is via the 1/2 hybrid
    • Strongest coupling to the backward wave or isolation path within the ring
  • Isolation between half rings is a sum of the hybrid coupling and isolation of the input hybrid splitter

Left hand ring

Right hand ring

Commissioning Workshop Alan Wheelhouse

further tests
Further Tests
  • Directional coupler coupling
    • Forward: -40.5 to -39.8 dB (± 0.35 dB)
    • Reverse: -40.5 to -39.75 dB (± 0.375 dB)
    • Spec : 40 ± 0.5 dB
  • Directional coupler directivity
    • Forward: > 41 dB
    • Reverse: > 42 dB
    • Spec : >40 dB
  • Some degree of variation of coupling and directivity seen versus phase shift
    • Due to parasitic interaction with the phase shifter short circuit.
  • Cable attenuation : 0.048 dB/m at 1.3 GHz

Commissioning Workshop Alan Wheelhouse

llrf control system
Llrf control SYSTEM

Commissioning Workshop Alan Wheelhouse

emma llrf
  • Provides the stabilisation of the accelerating field
  • Results from tests at 5kW (~140kV) per cavity
    • Phase 0.0093° (Spec 0.3°)
    • Amplitude 0.006% (Spec 0.3%)
  • Libra system developed by I-Tech
  • Procedures being defined for the timing, cresting and phase setting
  • Presently under-going additional programming
    • For the stepper motors and the controllers
    • For adapting the system to lower sampling frequency (81.25MHz) to aid the timing issue

Commissioning Workshop Alan Wheelhouse

cabling connections
Cabling & Connections

Commissioning Workshop Alan Wheelhouse

cabling connections1
Cabling & Connections
  • LLRF rack designed
    • Build on going
    • Cabling being pulled in
  • Cavity
    • 2 thermal cut-out interlock switches fitted to the water circuits
    • In series with the water flow trip on the return
  • Tuner and phase shifter control
    • Drawings for PCUs and Lantronics systems being drawn up

Commissioning Workshop Alan Wheelhouse


Commissioning Workshop Alan Wheelhouse

  • HVPS Commissioning 1 day
  • Waveguide Distribution
    • Installation 3 days
    • Commissioning 3 days
  • LLRF
    • Cable calibration 3 days
    • Low power tests 1 week
    • High power tests 1 week
    • Screen layout 1 week
    • Commissioning In parallel with above work
  • Timescales dependent on electrical work

Commissioning Workshop Alan Wheelhouse