Transcript CLIC main linac acc. structure

CLIC
The new CLIC parameters
29.10.2007
Alexej Grudiev
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
Linear Collider major parameters
CLIC
• Energy reach
High accelerating gradient
energy loss
by beamstrahlung
• Luminosity:
wall-plug to beam
efficiency
wall-plug
power
AC
kb Nb2 f rep
 B1/ 2 beam
 PAC
L

*
*
 1/ 2
4 U cm  x  y
U  ny
cm
center-of-mass
energy
Vertical
emittance
• High Beam Power (several MWatts)
• Wall-plug to beam transfer efficiency as high as possible (several %)
• Generation & preservation of beam emittances at I.P. as small as possible (few nmrad)
• Beam focusing to very small dimentions at IP (few nm)
• Beamstrahlung energy spread increasing with c.m. colliding energies
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
CLIC overall layout
CLIC
Drive Beam
Generation Complex
326 klystrons
33 MW, 139 ms
drive beam accelerator
2.37 GeV, 1.0 GHz
1 km
326 klystrons
33 MW, 139 ms
drive beam accelerator
2.37 GeV, 1.0 GHz
combiner rings
delay
loop
Circumferences
delay loop 80.3 m
CR1 160.6 m
CR2 481.8 m
CR2
CR2
CR1
CR1
245m
delay
loop
245m
IP1
TA
R=120m
48 km
CLIC overall layout
3 TeV
e- injector
2.4 GeV
Alexej Grudiev, New CLIC parameters.
1 km
booster linac,
9 GeV, 2 GHz
BC1
e- DR
365m
e+ DR
365m
e+ injector,
2.4 GeV
Main Beam
Generation Complex
CARE07, 29 Oct. 2007
Old and new CLIC main parameters
CLIC
Old (2005)
New (2007)
3 TeV
3 TeV
Peak Luminosity
6.5·1034 cm-2 s-1
7·1034 cm-2 s-1
Peak luminosity (in 1% of energy)
3.3·1034 cm-2 s-1
2·1034 cm-2 s-1
150 Hz
50 Hz
150 MV/m
100 MV/m
Main linac RF frequency
30 GHz
12 GHz
Overall two-linac length
28 km
42 km
Bunch charge
2.56·109
3.72·109
Bunch separation
0.267 ns
0.5 ns
Beam pulse duration
58.4 ns
156 ns
Beam power/beam
20 MW
14 MW
660 / 10 nm rad
660 / 20 nm rad
60 / 0.7 nm
40 / ~1 nm
33 km
48 km
418 MW
322 MW
Center-of-mass energy
Repetition rate
Loaded accelerating gradient
Hor./vert. normalized emittance
Hor./vert. IP beam size bef. pinch
Total site length
Total power consumption
http://clic-meeting.web.cern.ch/clic-meeting/clictable2007.html
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
CLIC main linac optimization model
CLIC
<Ea>, f, ∆φ, <a>, da, d1, d2
BD
Bunch population
N
Ls, Nb
Cell parameters
Q, R/Q, vg, Es/Ea, Hs/Ea
Structure
parameters
Ns
Q1, A1, f1
Bunch
separation
BD
η, Pin, Esmax, ∆Tmax
rf
constraints
YES
Cost function
minimization
NO
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
Optimization constraints
CLIC
Beam dynamics (BD) constraints based on the simulation of the main
linac, BDS and beam-beam collision at the IP:
N – bunch population depends on <a>/λ, Δa/<a>, f and <Ea> because of
short-range wakes
• Ns – bunch separation depends on the long-range dipole wake and is
determined by the condition:
•
Wt,2 · N / <Ea> = 10 V/pC/mm/m · 4x109 / 150 MV/m
RF breakdown and pulsed surface heating (rf) constraints:
• ΔTmax(Hsurfmax, tp) < 56 K
• Esurfmax < 250 MV/m
• Pin/Cin•tp1/3 < 18 MW·ns1/3/mm @ X-band
Alexej Grudiev, New CLIC parameters.
(frequency dependent)
CARE07, 29 Oct. 2007
Frequency scaling of power constraint
CLIC
Experimental data at
X-band and 30 GHz
become available 2006
Scaled structures
Scaled structures show
the same gradient at
X-band and at 30 GHz:
Pin/Cin•tp1/3•f = const
Alexej Grudiev, New CLIC parameters.
Eatp1/6 = const
CARE07, 29 Oct. 2007
Optimization Cost functions
CLIC
1. Luminosity per linac input power (performance):
Lb Nb f rep
Lb
L
1




Pl e Ec N Nb f rep  e Ecm N
Figure of Merit
(FoM)
Collision energy is constant
2. Total cost parametric model (become available 2006)
Investment cost + Exploitation cost for 10 years
Ct = Ci + Ce
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
Optimization parameter space
CLIC
All structure parameters are variable:
<Eacc> = 90 – 150 MV/m,
f = 10 – 30 GHz,
Δφ = 120o, 150o,
<a>/λ= 0.09 - 0.21,
Δa/<a> = 0.01 – 0.6,
d1/λ= 0.025 - 0.1, d2 > d1
Ls = 100 – 1000 mm.
Alexej Grudiev, New CLIC parameters.
N structures:
7
14
2
24
60
61
4
-------------68.866.560
CARE07, 29 Oct. 2007
CLIC performance and cost versus gradient
CLIC
Ecms = 3 TeV
Performance
New
Previous
L(1%) = 2.0 1034 cm-2s-1
Cost
New
Previous
Optimum
• Performance increases with lower accelerating gradient
(mainly due to higher efficiency)
• Flat cost variation in 100 to 130 MV/m with a minimum
around 120 MV/m
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
CLIC performance and cost versus frequency
CLIC
Ecms = 3 TeV
L(1%) = 2.0 1034 cm-2s-1
Performance
New Optimum
Cost
Previous
New
Optimum
Previous
• Maximum Performance around 14 GHz
• Flat cost variation in 12 to 16 GHz frequency range with a
minimum around 14 GHz
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
CLIC Performance and Cost optimization
CLIC
Performance (a.u.)
CLIC
New parameters
CLIC
Old Parameters
Accelerating field
= 100 MV/m
Accelerating field
= 150 MV/m
RF frequency
= 12 GHz
Alexej Grudiev, New CLIC parameters.
Total cost (a.u.)
RF frequency
= 30 GHz
CARE07, 29 Oct. 2007
Interplay between BD and RF
CLIC
FoM = L1/N · η
BD
L1/N
RF
BD optimum aperture:
<a> = 2.6 mm
Why X-band ?
Crossing gives
optimum frequency
RF optimum aperture:
<a>/λ = 0.1 ÷ 0.12
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007
Summary
CLIC
• CLIC main linac optimization model taking into account
complex interplay between beam dynamics and rf
performance has been developed over the past few
years
• In 2006,
• new experimental data both at 30 GHz and at X-band have
been obtained
• CLIC total cost parametric model has become available
• Optimization of CLIC frequency and gradient has been
done which (together with some other considerations)
resulted in major change of CLIC parameters from
150MV/m at 30GHz to 100MV/m at 12GHz
Alexej Grudiev, New CLIC parameters.
CARE07, 29 Oct. 2007