CLIC MAIN LINAC DDSCLIC MAIN LINAC DDS
Vasim Khan
24 cellsNo interleaving
48cells2-fold interleaving
∆fmin = 32.5 MHz∆tmax =30.76 ns∆s = 9.22 m
24 cellsNo interleaving
∆fmin = 65 MHz∆tmax =15.38 ns∆s = 4.61 m
48cells2-fold interleaving
Summary of results
96 cells4-fold interleaving
192 cells8-fold interleaving
V. Khan LC-ABD 09, Cockcroft Institute 22.09.09 8/13
96 cells4-fold interleaving
∆fmin = 16.25 MHz∆tmax = 61.52 ns∆s = 18.46 m
192 cells8-fold interleaving
∆fmin = 8.12 MHz∆tmax =123 ns∆s = 36.92 m
Summary of results
A 1.19
GHz 11.9942
6101.61072.3
I19-9
For CLIC_G structure <a>/λ=0.11, considering the beam dynamics constraint bunch population is 3.72 x 10^9 particles per bunch and the heavy damping can allow an inter bunch spacing as compact as ~0.5 ns. This leads to about 1 A beam current and rf –to-beam efficiency of ~28%.
For CLIC_DDS structure (2.3 GHz) <a>/λ=0.126, and has an advantage of populating bunches up to 4.5x10^9 particles but a moderate Q~500 will require an inter bunch spacing of 8 cycles (~ 0.67 ns).
A 1.13
GHz 11.9942
8101.6104.75
I19-9
V/pc/mm/m 1.71072.3150
10410010W
9
9limitT
V/pc/mm/m 5.6104.75150
10410010W
9
9limitT
Though the bunch spacing is increased in CLIC_DDS, the beam current is compensated by increasing the bunch population and hence the rf-to-beam efficiency of the structure is not affected alarmingly.
CLIC_G vs CLIC_DDS
Parameters CLIC_G (Optimised)
[1,2]
CLIC_DDS(Single
structure)
CLIC_DDS(8-fold
interleaved)
Bunch space (rf cycles/ns) 6/0.5 8/0.67 8/0.67
Limit on wake (V/pC/mm/m) 7.1 5.6 5.3*
Number of bunches 312 312 312
Bunch population (109) 3.72 4.7 5.0*
Pulse length (ns) 240.8 273 272.2*
Fill time (ns) 62.9 42 40.8*
Pin (MW) 63.8 72 75.8*
Esur max. (MV/m) 245 232 236
Pulse temperature rise (K) 53 47.3 51
RF-beam-eff. 27.7 26.6 26.7*
Figure of merit (a.u.) 9.1 8.41 8.29*
[1] A. Grudiev, CLIC-ACE, JAN 08[2] H. Braun, CLIC Note 764, 2008* Mean value of 8 structures
CLIC_G vs CLIC_DDS
Single structure vs. Interleaved structure
Interleaved structures
Single structure
Interleaved structures
Single structure
Single structureSingle structure
Mean ofinterleaved structures
Mean ofinterleaved structures
Sumwake: 8-fold interleaved structure
Mean deviation RMS sumwake
Random error
RMS ∆f = 3.5 MHz
Random error
RMS ∆f = 2.4 MHz
Eight fold Interleaving
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
1 9 17 185
Single structure
2 10 18 186
3 11 19 187
4 12 20 188
5 13 21 189
6 14 22 190
7 15 23 191
8 16 24 192
Decoupling end cell from each structure
Decoupling 2 end cells from each structure
Decoupling both the end cells from each structure
Decoupling two end cells from either side from each structure
Decoupling first cell and two end cells from each structure + RMS 2.5 MHz Random error
Decoupling first cell and last cell from each structure + RMS 2.5 MHz Random error
A typical geometry : cell # 1
R
h
r1
h1
L
a1
t/2
a
b
Rc
a
a+a1
R
Structure GeometryCell parameters
a1
t/2
a
L
b
Rc
a
a+a1
RIris radius Iris radius
Cavity radius Cavity radius
Sparse Sampled HPT (High Power Test)
Fully Interleaved8-structures
amin, amax= 4.0, 2.13
bmin, bmax= 10.5, 9.53
Structure GeometryCell parameters
a1
t/2
a
L
b
Rc
a
a+a1
RIris thickness Iris thickness
Ellipticity Ellipticity
Sparse Sampled HPT (High Power Test)
Fully Interleaved8-structures
t
a 2ε 1
tmin, tmax= 4.0, 0.35
εmin, εmax= 1.0, 2.0
Structure GeometryManifold parameters
a1
t/2
a
L
b
Rc
a
a+a1
RDegree of manifold penetration
Manifold radius
Sparse Sampled HPT (High Power Test)
Fully Interleaved8-structures
Degree of manifold penetration
Manifold radius
Rcmin, Rcmax= 6.2, 7.5
Rmin, Rmax= 3.25, 2.3
Structure # 1 in an 8-fold interleaved design
Structure # 8 in an 8-fold interleaved design
Structure # 1 in an 8-fold interleaved design
Structure # 8 in an 8-fold interleaved design
Structure # 1 in an 8-fold interleaved design
Structure # 8 in an 8-fold interleaved design
Sparse Sampled Structure
Structure # 1 in an 8-fold interleaved design
Structure # 8 in an 8-fold interleaved design
Sparse Sampled HPT (High Power Test)
Fully Interleaved 8-structures
dn/df
Kdn/df
dn/df
Kdn/df
dn/df
Kdn/df
dn/df
Kdn/df
Sparse Sampled HPT (High Power Test)
Fully Interleaved 8-structures
Structure # 1 in an 8-fold interleaved design
Structure # 8 in an 8-fold interleaved design
SRMS: Random errors with 20 iterations
∆f = +/- 4.0 MHzRMS ∆f ~ 2.3 MHz