European Organization
for Nuclear Research
Failure Studies at the Compact Linear Collider: Main
LINAC and Beam Delivery System
Carlos O. Maidana* and Michael Jonker*
CERN - Technology Department
Machine Protection & Electrical Integrity Group
Performance Evaluation Section
*CLIC Operations and Machine Protection Working Group
Layout for the Compact Linear Collider
Current tasks being performed under the
CLIC Operations & Machine Protection WG
Perform a systematic failure study
Main Beam LINAC
Beam Delivery System
Failures of
different types
Damage in
different locations
Kick study
i.e. damage produced for kicks at different
locations of the beam line.
•
•
•
•
•
Quads short
RF breakdown
Injection failures
Stabilization
problems
Others
One failing element
Multiple failing elements
Power Extraction and Transfer Structures (PETS)
View of a CLIC 12 GHz two-beam module highlighting the CLIC power extraction and transfer principle. One
module contains up to four power extraction and transfer structures (PETS), where each PETS feeds two
accelerating structures. RF waveguides transfer the RF power generated from the PETS into the accelerating
structures. Quadrupole magnets are used for strong focusing of both beams. Picture : CLIC study.
Base computer software
Tracking code w/misalignments
& wakefields considerations
OriginPro
Main LINAC beam dynamics
Size X ~ 1.86 mm (s)
Size Y ~ 0.46 mm (s)
Size Z ~ 43.5 mm (s) (Max /Min 126 mm)
Energy ~ 1.5 TeV (1.3% DE/E0)
Number of e-/+ per bunch = 3.72 109
Number of slices = 25*15
Number
of macro-particles = 150,000
.
Main LINAC beam dynamics and kick studies
Linear beam dynamics studies using PLACET and Origin Pro.
Shown is the average envelope evolution through the main
LINAC for different kick strengths applied over the 801st Quad.
Unperturbed beam
profile (y-y’) at the main
LINAC exit.
.
Perturbed beam profile at the
main LINAC exit after a kick of
2.9 mrad is applied on the 801st
Quad.
Perturbed beam profile at the entrance (red) and
at the exit (blue) on the 801st Quad to validate
PLACET behaviour.
Beam dynamics and Kick studies
Longitudinal linear beam
dynamics studies using
PLACET and Origin Pro.
Shown is the z-y plane
bunch profile at the LINAC
end for different kicks
applied over the 801st
quadrupole
The effect of the intrabeam (head-tail) transverse
wakefields can be seen.
Beam perturbed in steps of 4 um vertical
Unperturbed beam
.
head
tail
Perturbed beam:
2.9 mrad (20 um) vertical
Intra-beam wakefield
Longitudinal wakefield
Transversal beam dynamics
and kick studies
Beam blow up as a function of kick,
simulated for a quadrupole
displacement using the PLACET
code. Shown is the y’-y plane at the
LINAC end for various kick strengths
on the 9th quadrupole.
Unperturbed beam
Perturbed beam. Ellipse : chromatic effects and energy
spread. Islands: wake fields
Bunch
Bunch
Material damage caused by the LINAC beam
Charge density at the end of the LINAC
for 20 mm displacement at the 9th
quadrupole.
Perturbed beam
Train
Train
Unperturbed beam
•
•
•
•
Deep blue: safe for copper
Grey blue, destroys CU, safe for Be, Ti
Light blue, destroys CU, Be, safe for Ti
Green and above, unsafe for CU, Be, Ti
Beam Delivery System (BDS)
The CLIC collimation section fulfills 2 critical functions
• Removes the beam halo.
• It protects the down-stream beam line and detector against missteered beams from the main LINAC.
Beam Delivery System (BDS)
CLIC collimation
constitute a passive protection system
Energy errors
(energy collimator)
• Intensity errors
(i.e. charge injection or drive beam failures)
• RF phase errors
Betatron errors
designed to withstand a
full beam train
(betatron/transverse collimators)
• Quadrupole related failures
sacrificial
Beam Delivery System (BDS)
Size X ~ 44.93 nm (s)
Size Y ~ 1.58 nm (s)
Size Z ~ 44 mm (s) (Max /Min 126 mm)
Energy ~ 1.5 TeV (1.3% DE/E0)
Number of e-/+ per bunch = 3.72 109
Number of macroparticles = 150,000
Material damage caused by the BDS beam
Undisturbed 1.5 TeV beam at the collimators
Energy collimator
(ENGYSP)
Charge density with
less than 25 times the
destructive power of Cu
found almost everywhere.
A few pockets of higher
charge density able to
destroy Cu and Be can be
seen on the distribution
edges.
Betatron collimator
(YSP1)
Maximum charge density
Cu: 4 10-4 nC μm-2,
Ti-alloy: 4.5 10-3 nC μm-2
Be: 3.0 10-3 nC μm-2
Transverse space (x-y)
at the collimator
Charge density
at the collimator
1 bunch
Material damage caused by the BDS beam
& beam dynamics at the collimators
20 mm
24 mm
28 mm
9th
11.56 mrad
13.87 mrad
16.18 mrad
2.90 mrad
3.48 mrad
4.06 mrad
801st
1.32 mrad
1.58 mrad
2001st
Betatron collimator entrance
1.85 mrad
1 bunch
1801st
Material damage caused by the BDS beam
20 mm
24 mm
28 mm
9th
11.56 mrad
13.87 mrad
16.18 mrad
2.90 mrad
3.48 mrad
4.06 mrad
801st
1.32 mrad
1.58 mrad
2001st
Betatron collimator entrance
1.85 mrad
1 bunch
1801st
Beam Delivery System (BDS)
wakefields reach ~ 5-9 bunches
Kick: 1.32 mrad / 20 mm (v)
Kick: 1.85 mrad / 28 mm
collimator
Group of 5 & 15 bunches reaching
the betatron collimator YSP1 after a
1.32 mrad (20 mm) vertical kick was
applied on the main LINAC
quadrupole 1801. Tail formation
and interaction due to the
wakefields can be seen.
1 train = 312 bunches
bunch
train
train
Material damage caused by the BDS beam:
phase advance effect
11th
28 mm / 16.18mrad
10th
50 mm / 28.9 mrad
1 train
Betatron collimator entrance
9th
36o phase advance between quadrupoles
28 mm / 16.18mrad
9th
10th
50 mm / 28.9 mrad
Betatron collimator entrance
Material damage caused by the BDS beam:
phase advance effect
36o phase advance between quadrupoles
11th
28 mm / 16.18mrad
9th
10th
50 mm / 28.9 mrad
Betatron collimator entrance
Material damage caused by the BDS beam:
phase advance effect
36o phase advance between quadrupoles
11th
1801st
1802nd
50 mm / 3.3 mrad vertical
36o phase advance between quadrupoles
1803rd
1 train
Betatron collimator entrance
Material damage caused by the BDS beam:
phase advance effect
Material damage caused by the BDS beam
Quadrupole 1801: 50 mm / 3.3 mrad vertical
Tail
Tail
Head
Betatron collimator
(YSP1)
Destruction of the
betatron collimator
Collimator
(lower section)
Head
Energy collimator
(ENGYSP)
No effect on the
energy collimator
Half intensity
1 train
9th Quadrupole - 50 mm / 28.9 mrad
Betatron collimator entrance
Reduced intensity beam
Nominal intensity
9th Quadrupole
1 train
Betatron collimator entrance
Reduced beam intensity: extreme cases
28 mm / 16.18mrad
50 mm / 28.9 mrad
Quad 2001: 50 mm / 3.3 mrad vertical
1 train
Quad 1801: 50 mm / 3.3 mrad vertical
Half intensity beam
Betatron collimator entrance
Reduced beam intensity: extreme cases
9th Quadrupole - 50 mm / 28.9 mrad
1 bunch
Betatron collimator entrance
Variable beam intensity: injection errors
95% of nominal
intensity
Nominal intensity
105% of nominal
intensity
9th Quadrupole - 50 mm / 28.9 mrad
1 train
Betatron collimator entrance
Variable beam intensity: injection errors
95% of nominal
intensity
Nominal intensity
105% of nominal
intensity
Variable beam intensity: injection errors
9th Quadrupole - 50 mm / 28.9 mrad
Nominal
intensity
105% of nominal
intensity
1 bunch
Energy collimator entrance
95% of nominal
intensity
Other studies being performed
• Phase errors
• Damage on the energy collimator
• Induced currents and its effects on collimators (and other metallic
structures)
• Benchmark of software for machine protection
• Studies on the horizontal plane
European Organization
for Nuclear Research
Carlos O. Maidana and Michael Jonker
CERN - Technology Department
Machine Protection & Electrical Integrity Group
Performance Evaluation Section
European Organization
for Nuclear Research
Coupled RF cavity system for energy transfer
Drive beam
Main beam
High current, low energy
Low current, high energy
Energy: 1.5 TeV
e- e+
Main Beam at LINAC Injection
Energy, Eb
9 GeV
Number of particles/bunch, Nb
3.72 109
Bunch length, ss
44 mm
Energy spread, DE/E0,inj
1.3 %
Transverse normalized horizontal emmitance, gbex 600 mm mrad
Transverse normalized vertical emittance, gbey
10 mm mrad