Transcript No Slide Title

NLC - The Next Linear Collider Project
Accelerator Instrumentation,
Controls and Diagnostics
Friday, May 31, 2002
Marc Ross
J/NLC
CLIC
TESLA
Does Accelerator-Based Particle Physics
Have a Future?
• We can't just leave the design of frontier accelerators to the
specialists. Inventing clever new ideas requires the same
talents that it takes to do experimental physics.
Maury Tigner
Physics Today – January 2001
Assuming this to be basically correct …
How can we make it work?
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
2Slide
#
J/NLC
CLIC
TESLA
This talk:
• Only suggests the nature of collaborative efforts (phase change?)
– Not a set of requisitions carved up in detail
• Does not detail ‘plug and play’ activities
• Is not a ‘status’ update
– Does not detail who is up to what
• Illustrates technologies and hints at opportunities
• is NLC/TESLA/CLIC neutral
» (other projects….?)
• SLC Experience:
• Substantial contributions from collaborators
– especially software
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
3Slide
#
CLIC
J/NLC
TESLA
Limiting LC technology:
•
•
•
•
•
•
•
•
•
•
•
(not including physics of beams)
gradient & RF power & associated diagnostics
Low power mwave circuitry
Lasers
Positioning/alignment/vibration stabilization
mm wave & FIR diagnostics
Data flow – control system
Radiation effects
Vacuum
Feedback
Engineering – fabrication, packaging, testing
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
4Slide
#
Block
diagram of
the ‘simple’
part of an
LC
timing, f
amp
distribution
LLRF
pickup
LINAC
beam
control
acc
signal
processor
data
J/NLC
CLIC
TESLA
“Precision” microwave
• High power controls and monitoring + position monitors +
beam phase monitors
– Cavity tuning at TESLA; lorentz force compensation + coupling
control
• programmed phase control
• external measurements of phase and amplitude
– TESLA Test Facility uses a sequence of stabilization loops and
associated processors
– NLC/SLC uses thermal stabilized power and phase measurements
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
6Slide
#
Amplitude at each DLDS Output
DLDS Waveforms with Beam Loading Compensation
0
500
1000
1500
Time (ns)
2000
2500
3000
Linac LLRF Drive
Timing
System
DDS Update
Memory
State
DDS
Clock
300 MHz
High Speed
DDS
Transition
Amplitude
Time
LO2
10.7 GHz
LO1
625 MHz
IF1
89.25
MHz
Lowpass
120 MHz
MIXER
Frequency
Phase
df/dt
1
xxx
xxx
xxx
xxx
xxx
2
xxx
xxx
xxx
xxx
xxx
3
xxx
xxx
xxx
xxx
xxx
:
:
:
:
:
:
Bandpass
714 MHz
DLDS
IF2
714
MHz
MIXER
Bandpass
11.4 GHz
Klystron
Klystron
Klystron
Klystron
Klystron
Klystron
Klystron
Klystron
TWT
TWT
TWT
TWT
TWT
TWT
TWT
TWT
DDS
States
100 MHz
Modulated
11.424 GHz
NLC Linac LLRF
Measurement Requirements
Parameter
Value
Details
Bandwidth
> 100 MHz
at -3 dB
Rise time
< 5ns
10% to 90%
Phase resolution
1 degree
At 11.424 GHz
Dynamic Range
> 20 dB
Amplitude Resolution
10-3 of full scale
Beam phase wrt RF
1 degree
At 11.424 GHz
Beam signal / RF
-40 dB
(!)
Reflected power detector max input
< 100 mW
Peak
Reflected power detector rise time
< 10 ns
CLIC
J/NLC
TESLA
TTF LLRF Drive Controls
S. Simrock
Also have
tuners,
coupling etc.
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
10
Slide #
J/NLC
CLIC
TESLA
Final Doublet support girder
• Internal to detector
• Compact Superconducting Quads are the superior
technology because of their flexibilty and are the most
likely candidate for the final doublet
• R&D in SC Quads is still in the conceptual state
• SLAC team working with PM
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
11Slide
#
LCD-L2 (3T) with 3.8m L* Optics
52 mrad Cal
acceptance
32 mrad M1
acceptance
0.2
Calorimeter
0.15
M1
0.1
SF1
QF1
M2
SD0
QD0
0.05
Feedback BPM &
Kicker
0
Low Z
shield
6.3 mrad
Lum-Mon
acceptance
-0.05
Beampipe
-0.1
Pair LumMon
1 mrad exit
aperture
-0.15
Support Tube
-0.2
02
46
8
10
12
Development of a transition
radiation profile monitor -OTR
• some controversy over minimum
resolvable beam image
– achieved 7mm (12/00) well beyond
purported limit – OTR provides light at
very large angles  high resolution
– not like synchrotron light
– smallest OTR spot imaged to date
• theoretical limit: ~ l
• Parameters for ATF OTR (built at SLAC)
– resolution – 2mm
– field of view – 300 x 200 mm (or ~2x)
– depth of field – 8 mm vertical
displacement
SLAC–built very high resolution OTR
– OK light for normal camera – 5e9 ppb
– Industrial microscope objective
– 35 mm working distance
– various target materials
Also – ‘Diffraction Radiation’ from an aperture/edge
0.5mm
10 mm s_y
OTR images & target damage
successive images illustrating damage:
Cu
7e9
20x12mm
Be 5e10
10x13mm
J/NLC
CLIC
TESLA
Bunch length
• Streak cameras
– resolution limited to ~ 1mm
– space charge, calibration
• Coherent radiation
– stronger signal with shorter beams
– asymmetry difficult (use power spectrum – phase info lost)
• Deflecting RF structures
– promising 
• Broadband microwave emission
– cheap, relative – a given
• accurate monitor critical for short wave FEL
Multi-stage compression
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
15
Slide #
CLIC
J/NLC
TESLA
LCLS Bunch length monitor
•
S-band deflecting TM11 structure
Schematic:
RF Input
Coupler
Irises with
mode-locking
holes
Beam
Deflection
May 31, 2002
l rf
Ed Es
sz 
2 eV0 sin  cos 
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
s
2
y
 s2y 0 
d  s
Author Name
Date
16
Slide #
Bunch length monitor Transverse RF Cavity for Bunch Length and Slice-Emittance Measurements
(J. Frisch, X.-J. Wang, old SLAC ’60s)
~sz
V(t)
e
q
t
f 20
‘screen’
e for V = 20 MV
sz  sx)
e for V = 0; sx0
sz 
lE
s x2 s x20
2 eV0 cos 01sin 
V  20 MV at   20°
Storage ring instabilities – electron cloud
A diffuse cloud of electrons gathers quickly and surrounds the
positron (proton) beam.
Electrons generated by photoelectric/secondary emission
Very serious impact on b-factory / damping ring design and
operation
Effect of train gap
25
Electron cloud
effect in KEK-B LER
Showing the rise time
of cloud density
Bunch spacing ~ 5 ns
Vertical beam size(a.u.)
20
15
10
5
gap of 32 buckets
0
01
0
203
04
Bunch
05
06
0
70
J/NLC
CLIC
TESLA
Buildup of
electron cloud as
a function of
time
•
•
•
•
during bunch train
passage
for 3 nominal bunch
intensities
(simulation)
very little done for
‘direct’ measurements of
cloud
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
20
Slide #
J/NLC
CLIC
TESLA
Radiation modeling
ep+
prompt residual
prompt residual
• Collider single beam power ~ 14 MW
– (1 Rad/hr ~ 0.3 mW into 1 kg of material)
• Need to model:
– locally installed electronics/plastics radiation dose
• how much local shielding is needed?
• Optics/Lasers/Electronics/HV power supplies/mwave components/?
– material damage from extreme radiation
– background processes for a variety of detectors
• (not limited to IR)
– machine component ‘damage’ processes
– environmental – (NUMI)
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
21
Slide #
1.0E+14
560
5.6E+13
600
3.2E+13
1.8E+13
1.0E+13
540
500
5.6E+12
3.2E+12
1.8E+12
400
1.0E+12
520
5.6E+11
300
3.2E+11
1.8E+11
500
1.0E+11
200
5.6E+10
3.2E+10
1.8E+10
100
480
1.0E+10
5.6E+09
0
0
50
100
150
200
250
300
3.2E+09
350
1.8E+09
460
260
270
Tunnel electronics enclosures in main
linac tunnel wall
280
290
300
310
320
330
340
estimate of neutron fluence for
1.4W steady loss for 3000 days of
operation
1.0E+09
FFTB Single Pulse Damage Coupon Test - front and back side - same scale
2 1010 8 x 6 mm
Front
Back
Front
2 1010 8 x 6 mm
Back
2 1010 9 x 8 mm
Front
Front
Back
2 1010 9 x 11 mm
Back
J/NLC
CLIC
TESLA
RF Breakdown Diagnostics
• Goals:
– Location within mm
– Quantify energy deposition
• Comprehensive recording
– Observe emitted light
• Provide feedback to manufacturing & fabrication process
• Optimize conditioning protocol
• Observations:
– Multi-breakdown events caused by reflection
– Breakdown grouping in time
– Structure damage is not explained by material removed by arc pits
themselves
– Many (most) structures show enhanced concentration of breakdown in WG
coupler
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
24
Slide #
J/NLC
CLIC
TESLA
X-band (NLCTA) acoustic emission
• Clearly audible sound from breakdown – heard from n-1
generation transport components (e.g. flower petal mode
converter, bends)
• Small, 1MHz bandwidth industrial or homemade sensors
• 10 MHz bandwidth recorders (3 samples/mm)
– Look for start time (TTF) of ‘ballistic phonons’
– or Amplitude (NLCTA)
• Broadband mechanical impulse
– (2001- limited by sensor performance)
– Typ. l ~ 7 mm
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
25
Slide #
Acoustic sensor studies of input
coupler breakdown
Plan views of two input coupler assemblies
T53 VG3 F (KEK; diffusion bonded cell)
T53 VG3 RA (SLAC; H2 braze)
Structure input coupler  exactly where are breakdown events?
 acoustic imaging in copper
Acoustic sensors mounted on x-band
structure
CLIC
May 31, 2002
J/NLC
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
TESLA
Author Name
Date
29
Slide #
J/NLC
CLIC
TESLA
Global Accelerator Network “GAN”
• Proposal to ICFA from Wagner 3/00
– Task force (Astbury/Willeke) report 12/01
• Primary purpose to develop global collaboration for LC
construction and operation
• Many questions: Will GAN provide 
1.
2.
3.
4.
non-host labs with justification for personnel costs?
non-host labs with venue for R D?
host lab with staff?
continuation of involvement following construction
Who benefits from GAN?
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
32
Slide #
J/NLC
CLIC
TESLA
Some GAN opinions - mine (answers?)
• GAN DOES NOT PROVIDE JUSTIFICATION FOR
NON-HOST LAB STAFFING
– there must also be projects…
• The purpose of GAN is to maintain involvement/demand
ongoing responsibility of those who built.
– NOT like HERA, PEP2, SNS, LHC….
– Construction proceeds through strong collaboration
• Why do you care?
– How do you see the evolution of your involvement in the LC?
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
33
Slide #
J/NLC
CLIC
TESLA
Example university involvement in NLC RD
• Feedback on nanosecond time scales (Oxford U – Burrows)
– Two students posted at SLAC
– Engineer and one student at Oxford
• Students operate NLCTA & are fully ‘trained’
• If a medieval institution like Oxford U can contribute to LC
RD then so can you!
May 31, 2002
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
34
Slide #
Concrete ideas about how to connect
Developed a kind of list – see Tom Himel
Electronics engineering
Calibration, ‘high performance’ mixers
Very similar to precision detector daq.
1. Precision microwave
2. IR final doublet girder (~ internal to detector)
Mechanical engineering
Magnetics, acoustics
~ similar to VXD supports
3. Beam size from optical transition/diffraction radiation
4. Bunch length
FIR / mm wave optics,
imaging and calorimetry
Basic EM
5. Storage ring instabilities – electron cloud
Precision optics
Electrodynamics of OTR
VUV/Xray optics
Materials science, surface
science, electron
detectors/energy analyzer
J/NLC
CLIC
TESLA
Modeling, including known
radiation effects
Similar to LHC design work
6. Radiation modeling
7. Permanent Magnets
8. RF breakdown
9. Control system
May 31, 2002
Mechanical engineering
Field measurements, field
stability
Instrumentation, microwave,
acoustic, materials/surface
science
Large scale software
engineering, ~ similar to
detector systems
Accelerator Instrumentation, Controls & Diagnostics
- Marc Ross – SLAC
Author Name
Date
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Slide #