K Ronald University of Strathclyde For the MICE RF team 1 MICE Project Board 17th April 2015 Content 2 Redesigned distribution network Change from STEP V design Used underfloor delivery T ID: 573541
Download Presentation The PPT/PDF document "Status of the MICE RF System" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Status of the MICE RF System
K Ronald, University of StrathclydeFor the MICE RF team
1
MICE Project Board, 17th April 2015Slide2
Content
2
Redesigned distribution network
Change from STEP V design
Used under-floor delivery
T
he demonstration experiment has simpler distribution requirements
Now makes sense to use ‘over air gap’ network
Status of RF drive systemPlans for test, delivery and installation of amplifiersDevelopment of LLRF controlsStatus of the LLRF resourcesMuon-RF phase determinationInitial tests with waveforms from MTA testsHardware now at Strathclyde for RF tests
MICE Project Board, 17th April 2015Slide3
MICE HPRF systems
3
MICE HPRF system requirements have changed
Fewer cavities, no coupling coil
Required operational date is Summer 2017
Enables demonstration of ionisation cooling with re-acceleration
Data campaign complete before end US fiscal year 2018
The MICE Demonstration of Ionisation Cooling requires
Two individual cavities bracketed by two thin LiH absorbers, sandwiching main absorberCavities themselves are unchangedEach cavity is 430mm long with a Q of 44,000 and is resonant at 201.25MHzThe cavities must still operate in a strong magnetic field environment
Cavities are estimated (by simulation) to deliver 8MV/m at 1MW dissipation- shunt impedance 5.9 M
W
A.
Bross
has reported on the ongoing tests at FNAL
MICE Project Board, 17th April 2015Slide4
MICE HPRF systems
4
The MICE Demonstration of Ionisation Cooling requires
Two
individual cavities bracketed by two thin
LiH
absorbers, sandwiching main
absorber
Cavities Technical DetailsEach cavity is 430mm long with a Q of 44,000 and is resonant at 201.25MHzThe cavities must still operate in a strong magnetic field environmentCavities are estimated (by simulation) to deliver 8MV/m at 1MW dissipation- shunt impedance 5.9 MW2MW peak output from RF drive amplifiers, also unchanged
LLRF requires ~10 % overhead to achieve regulation
Estimated ~10 % loss in transmission line
Power delivered to each cavity 1.62 MW,
Anticipated gradient in each cavity 10.3 MV/m
Slight uplift in gradient from 7.2 MV/m in each ‘STEP V’ cavity
MICE Project Board, 17th April 2015Slide5
RF network: STEP V/VI
5
MICE Project Board, 17th April 2015
Amplifiers installed behind shield wall
Triodes on main floor,
Tetrodes
on Mezzanine
Impact of B-fields negated by yokeLine installation planed before yoke support risersHigh power dynamic phase shifters removed 4 off 6 inch coax lines over wall
Pressurised to increase power handlin
g
Line lengths matched using 3D CAD
Manually adjustable line trimmers installed at
cavity to take up assembly errors in coax length
Flexible coax final feeds
Allows for small misalignments
10 hybrid splitters Split power for the opposed couplers of each cavity
Lines will be pressurised with 2Bar Nitrogen
Amplifiers behind Shield Wall
Distribution Network to MICESlide6
RF network: Demonstration experiment
6
MICE Project Board, 17th April 2015
Offcentre
mounting of hybrid allows neat take up of 90 degree phase
Orientation of load arbitrary- plan to align with the 6” distribution line and share mountings
Minimised length of 4” line- minimises breakdown and losses
Flexible coax
Line TrimmersHybrid Splitter
Directional
Coupler in
each line
4616 Pre Amplifier
TH116
Amplifier
500kW Load
Directional
Coupler 6 inchSlide7
RF network: Demonstration experiment
7
MICE Project Board, 17th April 2015
Propose
to have
1 load
on the hybrid splitter to each RF
cavity
absorbs unbalanced reflectionsCrane hook height fully retracted does not clash with the coax over the wall.Support for network will be from present ‘shield wall’ and from yoke supportsSlide8
RF network: Demonstration experiment
8
MICE Project Board, 17th April 2015
2
nd
TH116 amplifier moved to 3
rd
position behind wall to use the space
and ease installation in congested areaWith only 2 RF amplifiers now relatively straightforward to place auxiliary systems (cooling)Water cooling for load will need to route over the air gap on the transmission linesSlide9
RF network: Demonstration experiment
9
MICE Project Board, 17th April 2015
Offcentre
mounting of hybrid allows neat take up of 90 degree phase
Orientation of load arbitrary- plan to align with the 6” distribution line and share mountings
Minimised length of 4” line- minimises breakdown and lossesSlide10
RF network: Demonstration experiment
10
MICE Project Board, 17th April 2015
With slightly higher mounting of the RF network, work platform can be accommodated above channel
Such a platform can be useful for RF and other work
RF assemblies from hybrids to flexible lines can be prebuilt and craned in as components
Rapid assembly and servicing/accessSlide11
Implications for Power Distribution Network
11
The change to a two cavity system has some implications for the RF line loading
New experiment will demand higher power (1MW peak, 1kW average) in 4” lines under floor
Plan to implement SF
6
insulation
4” lines and components rated to 1.12MW peak in air at 1 bar (data from manufacturer/supplier)
Likely during full reflect during cavity fill we will have up to double the voltage on the line (eq. to 4MW)This will be mitigated by slow fillAlso mitigate with insulating gas
MICE Project Board, 17th April 2015Slide12
HPRF System Status
12
MICE RF systems demonstrated
N
ominal power levels 2MW, Frequency (201.25MHz) for 1ms @ 1Hz
First amplifier tested in MICE hall
Triode amplifier (output stage) remains installed
Tetrode and all modulator racks shipped to Daresbury
New higher voltage solid state crowbar testedElectrical completion of triode No. 2 will commenceTriode 2 will be tested using No. 1 tetrode and modulatorsWill use upgraded Triode No.1 modulatorEach major No. 1 subsystem will be swapped for No. 2 sequentiallyMake fault finding more rapidRemote control philosophy being developed
Will be tested during commissioning of No. 2 system
Dependent on electrical engineering resource availability
No 1 tetrode ready for re-commissioning at DL
July 2015, Triode No 2 tests with No 1 racks and tetrode
Design/Build Control Rack for No 1 racks- August 2015
Nov 2015, No 2 amplifiers tested with No 1 racks & controls
MICE Project Board, 17th April 2015Slide13
Cooling Demonstration: Preparation Programme
13
From STEP IV the project becomes increasingly focussed on RF systems
Relevant to define RF de-risking programme
First cavities expected May 2016
Opportunity to perform system shakedown
Cavity can be installed ‘upstream’ and parallel to
beamline
enclosureInstallation between ISIS run cyclesOpportunity to test vacuum pump down and clean and bake cavitySpecial transmission lines can be run from amplifier station no 1Shielding can be provided across hall near upstream SSTriode amplifier No 1 already installedRequire re-installation of entire RF amplifier chain
Aux racks, Modulator racks, SSPA, Tetrode amplifier
Require automation and control logic
Require LLRF system
Timing diagnostic: development of hardware
Tested on bench at Strathclyde
Test at MTA
MICE Project Board, 17th April 2015Slide14
Preparation Programme: Timeframes
14
Amplifier No 1 programme
Definition of controls and automation system/interfaces/interlocks
End April 2015- Draft documents under review
Amplifier no 1 automation system on PSU completion during 2015
Commission and test amplifier no 2 with automation & no 1 racks, Nov 2015
Re-Installation and test into loads at RAL with triode no 1, mid Aug 2016
Key resources, Electrical Engineering Effort 1 FTE EE, 0.5 FTE ED, 1 FTE ET, 0.5 FTE CE, 0.4 FTE MTControl and Monitoring programming: Pierrick
Hanlet
+ DL CE
RF & EE system specification/RF & EE system testing: T Stanley, C White, S Griffiths, S
Alsari
, K Ronald, CG Whyte, AR Young with consulting input from A Moss1-2 months of test operation through 2015, 2 months installation time. Team drawn from above list (minimum 2, ideally 3 required at any time)
MICE Project Board, 17th April 2015Slide15
Preparation Programme: Timeframes
15
Cavity No 1 programme
Arrival May 2016:
Assume the modules
are delivered assembled from LBNL
Test tuning and prepare for vacuum operation
Require clean room, may require tuning of couplers
Require exercising of the tuners2 weeks, RF (Ronald, Stanley, Whyte, Alsari) and mechanical techniciansPrepare for evacuation, pump, gauge installation: Vacuum engineer and mechanical technicians4 weeksInstall in upstream space beside beamline
(or next to shield wall)
, install X-ray shield
2 weeks
Evacuation, Baking, estimate 2 weeks (RF and Vacuum Engineering)
Install, tune overhead RF lines, 2 weeks concurrent with evacuation (RF, Mech. Technicians)
Retest of cavity tune after bake and evacuation, 1 week
Potential to be ready around July 2016
MICE Project Board, 17th April 2015Slide16
Preparation Programme: Timeframes
16
HPRF Tests, can start late August 2016, 4 weeks for each cavity
As soon as amplifier no. 1 is available
Requires modification of the controls system development
Hitherto one rack was planned to control two amplifiers
To facilitate tests would need to build discrete control racks for each system
Seems feasible given sufficient Electrical Engineering Resource through 2015-2016
Requires LLRF controlRequires RF staffing needs addressed urgently on the software sideSecond cavity can be commissioned partially in parallel and be ready for test as soon as 1st cavity completedBenefits
Full shakedown of RF system
Pre-prepped cavities by end 2016
MICE Project Board, 17th April 2015Slide17
HPRF System Controls
17
P
lans exist (in discussion) for the controls and monitoring interfaces required for the RF system and interfacing to other vital subsystems
Will allow expedited remote control and logging to be built as soon as effort is available
Each Cavity: 17 analogue inputs, 2 analogue outputs, 4 digital inputs (2 logic states)
Each RF system: 24 digital inputs (2 logic states), 4 digital inputs (3 states), 1 digital input (8+ logic states), 22 analogue inputs (12 are high, ~MHz, speed), 3 analogue inputs
Note many of these may be reasonably logically ‘
ANDed’ outside the control logic- simplifying the system and moderating cost and build time MICE Project Board, 17th April 2015Slide18
RF Control System
RF systems will require remote, automated control system
‘State Machine’ description being evolved by MICE Team
Headline list of primary states and required conditions below
18
MICE Project Board, 17th April 2015
OFF
No conditions
ENABLEDHardware keys insertedSTANDBY Heaters NominalHardware keysRF load coolant (
3)
RF
tube coolant
(5)
Compressed AirPSU coolantMains Quality
READY
PPS
RF
Permit
HT
enclosures shut Heaters NominalCavity and Vessel pressure NominalCavity coolant NominalCavity tuner pressuresSF6 pressureHardware keys
RF load coolant (3)
RF tube coolant
(5
)
Compressed Air
PSU coolant
Mains Quality
ONNominal RF waveforms Radiation & Arc sensorsPPS RF
Permit HT enclosures shut Heaters NominalCavity and Vessel pressure NominalCavity coolant Nominal
Cavity
tuner
pressures
SF
6
pressure
Hardware
keys
RF load coolant (3)
RF tube coolant
(5
)
Compressed Air
PSU coolant
Mains QualitySlide19
LLRF systems
MICE LLRF: provide 1% amplitude, 0.5
o phase regulation
Will control tuner system
LLRF system being developed by Daresbury LLRF group
Using digital LLRF4 boards already procured
First board operating at 201MHz in tests during August 2014
Synergy with ISIS requirements for LLRF system
For new ISIS LINAC amplifier test and commissioning standSimilar installation to the MICE amplifier test standSystem is closely related to the implementation for existing Daresbury accelerators0.1 % amplitude and 0.3o demonstrated in 1.3 GHz accelerating cavitiesPower ramp programming already demonstratedBoards will be tested during the amplifier commissioning programmeLLRF system no 1 resourcesCrate build up, A Moss and DL Electronics staff
Software: Expedite recruitment of experienced XILINX programmer: Synergistic with ASTEC/DL requirements:
Exploring use of software work at ISIS building on DL practice.
Completion of system No 1 by end 2015-
test at DL then RAL
19
MICE Project Board, 17th April 2015Slide20
Timing System, Desired Specification
We wish to know the difference between
Transit time of any of our
muons
(in essence through ToF1)
A zero crossing of the RF system in any cavity- choose the first cavity
Use
tracker measurement of trajectories to project forward to each cavity in
turnLLRF phase (0.5o) stability specification is ~3x stricter than the resolution desired for the RF timing system <20ps or <0.4% of the RF cycleIn turn specification for RF timing is ~3x stricter than ToF resolution 50ps ~1%Should mean the timing accuracy is ~1% of RF cycle, defined by ToFs resolutionStability, and/or accurate knowledge, of all parameters in the system will be important
Long cable runs, with dielectric insulated coaxial lines?
Phase relationship between the cavity fields and the signals on the test ports
Relationship between
ToF
signals and actual
Muon
transit
MICE Project Board, 17th April 2015
20Slide21
Overview of Timing Critical Elements
Sketch illustrates relationships of key components in the Demonstration experiment
Work in progress: Mathematical tests of digitiser interpolation
Test sensitivity to vertical resolution, temporal sample rate, noise
Work to be undertaken: Test TDC/Discriminators in 201.25 MHz environment
ToF
1
Cavity 1
RF Amp 1
LLRF
Beamline
HPRF
RF Drive
LLRF Feedback
TDC’s (
ToF
)
TDC’s (RF)
Digitisers
Datarecorders
RF
Clock
Trigger
Discriminators (RF)
Discriminators (
T
oF
)
ToF
Signals RG213
201.25 MHz LLRF MO
MO Signal (RG213)
Computers
RF Amp 2
HPRF
Cavity 2
RF Drive
Cavity 2 (RG213)
Cavity 1 (RG213)
MICE Project Board, 17th April 2015
21Slide22
‘Sub’
Nyquist digitisation
To acquire at Nyquist
on 200MHz would demand a sampling rate of ~1-2G.Sa/sec, for 1msDemands ~1 to 2MB per acquired channel, > 7.2GB/hr (assuming an 8 bit digitiser)400
m
s window presently being acquired at MTA- requires minutes of time to record traces
Fourier domain signal reconstruction
The Fourier transform of the
undersampled data maps the signal into its ‘unaliased’, relatively low frequency rangeWe may then retransform to the time domain to determine the time evolution of the signal at some arbitrary point in timeMust satisfy Nyquist on the linewidth- for our cavity natural linewidth is ~5kHz, effective linewidth is ~10kHz, so sampling rate ~few hundred k.Sa/sec should be sufficientWe assume 20M.Sa/sec, with 1ms we now have about 20kB per 8 bit recorded channel, data rate of ~72MB/hr per channel
MICE Project Board, 17th April 2015
22Slide23
Comparison of rebuilt 20M.Sa/sec subsampled oscilloscope signal with
5G.Sa/sec recording: LeCroy 625Zi
MICE Project Board, 17th April 2015
23
Visit to FNAL brought 100’s GB of data
Strathclyde has been processing these real traces using subsample Fourier domain reconstructionSlide24
T
iming hardware and Tests
Use TDC and discriminators used in ToF
system
TDC’s
CAEN V1290
25
ps
multi-hit25ps bin size maps to 7ps uncertainty (assuming Uniform PDF)LeCroy 4415A discriminatorsNeeds to be tested in RF environment (alternatives available)Use of same electronics as ToF mitigates systematic uncertainty & driftTDC hardware, discriminators and crates now assembled at Strathclyde.RF connection boards being fabricated to allow tests at RF frequenciesTo make efficient integration into DAQ ideally use VME digitisers for the sub-sample reconstructionAt present continue to use fast, 8 bit, DSO’s to capture signal
Plan to use CAEN V1761 digitisers
1GHz
, 4G.Sa/sec, 10 bit, 2 Channel
instrument
Capable of 57.6MS/Ch
24
MICE Project Board, 17th April 2015Slide25
Summary
25
MICE Project Board, 17th April 2015
Substantial redesign of distribution network
Mitigates installation conflicts (both schedule and potential physical)
Eliminates most of the 4” line
Control/Automation requirements defined in draft form
Needed to expedite control rack construction
Expedited construction of control rack No 1 can enable full system and conditioning in late 2016Will debug system ahead of operation in summer 2017LLRF staffing issue has emergedKey software expertise has left DaresburyRequire to address this urgently as also required to allow system test in late 2016
Possible solution based on development of DL system at ISIS
Fourier domain reconstruction progressing with REAL pick off data from MTA
Some variation in offset to understand
Hardware to test TDC approach largely assembled