Integration of layout components for beam dynamics control
S. Di Mitri (1.0 hr.)
20/06/2013 1 S. Di Mitri - USPAS CO - Lecture_Th_13
Credits:
S. Milton, P. Emma,
A. Zholents, FERMI Team et al.
BC2
2,E2
PI
space charge
CSR
smaller R56
Landau damping nonlinear E-chirp
linear E-chirp
SBBU
COMPRESSION – Energy, Geometry, Optics
20/06/2013 2 S. Di Mitri - USPAS CO - Lecture_Th_13
Pictures by M. Cornacchia, R.
Bartolini et al. S. Di Mitri et al.,
PRST-AB 15, 020701 (2012)
C-type chicane S-type chicane
x vs. Upstream Quad – K1
20/06/2013 S. Di Mitri - USPAS CO - Lecture_Th_13 3
COMPRESSION – Stages
x 1.01 m
single-chicane
double-chicane
CSR-induced -growth
minimized.
t0
late arrival,
higher energy,
less chirp
longer bunch,
less wake,
more chirp
~same bunch length
Self-correction against
charge and time jitter.
Microbunching instability has larger
gain stronger heating required
higher slice energy spread at the end
RF tols relaxed.
Pictures courtesy of
P. Emma, M. Venturini
M. Venturini et.al.,
PRST-AB, 10,
054403(2007)
4
Bunch TIME-ARRIVAL Monitor
VERTICAL RF DEFLECTOR
SCREENS
QUADRUPOLES
DIPOLE
# of shots
Arr
ival
tim
e [
fs]
Arrival Time Jitter
# of slices
n,x [m
m m
rad]
450pC, 6ps
Slice Emittance < 1 m
~ 1
6 m
m
Bunch Length
from Injector
(6ps fwhm)
t
E
Long. Phase Space:
,slice< 35 keV
Bunch duration
Curr
ent
[a.u
.] Bunch length
compression (1ps fwhm)
~ 2
.5 m
m
e-BEAM DIAGNOSTICS
S. Di Mitri - USPAS CO - Lecture_Th_13 20/06/2013
Pictures courtesy of
G. Penco et al.
TRANSFER LINE
20/06/2013 S. Di Mitri - USPAS CO - Lecture_Th_13
Linac End
FEL
TL
1. measure the optics here 2. computes optics matching here 3. propagates the design optics downstream
1. measure the optics here 2. propagates the design optics upstream 3. computes optics matching
R56=2.8 mm
R56=7 mm
Pictures courtesy of
M. Cornacchia, M.
Venturini et al.
TUNABLE R56
TL, R56 =1mm
TL, R56 <0.1mm
6
PC Injector
SPLH ,
LH
RF Photo-cathode Gun and Injector + up to1.35 GeV Linac
SPBC1 ,
DBD , MBD ,
BC1 BC2
V-DCAV
SCREENS SCREENS
COLLIMATORS
COLLIMATORS
FEL-1 HGHG
FEL-2 HGHG 2-stage
PHOTON SYSTEM
Photon Diagnostics Hutch + X-ray Transport + 3 Beamlines
Planar and APPLE-II type Undulators + RF BPMs + /e- Screens + Quad-movers
3 Collimation sections
4 optics Diagnostic Stations + 5 Spectrometers
RF Vertical Deflector for time-resolved measurements
2 Magnetic Bunch Length Compressors + 2 Bunch Length Monitors
20/06/2013
Layout Summing Up (Example)
S. Di Mitri - USPAS CO - Lecture_Th_13
20/06/2013 7 S. Di Mitri - USPAS CO - Lecture_Th_13
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1.0 nC 3.4 kA 1.2 m
0.2 nC 2.1 kA
0.85 m
NONLINEAR
LINEAR
SPIKY
SMOOTH
> 100%
< 10%
Which beam?
S. Di Mitri - USPAS CO - Lecture_Th_13
Pictures courtesy of
P. Emma
20/06/2013 9
CSR in magnetic compressors affects the projected emittance (in the bending plane): the effect is stronger for shorter bunches.
W in the linac affects the projected emittance (in both planes): the effect is stronger for longer bunches.
1111 0,0
0,
2
,
2
0,00,0 CSRi
i
CSR
ii X
1
0,
,
z
CSR
CQ
1112
21 0,
2
00,
222
0
0,0, Wff
fff
totFODOzeffff X
LLWQ
ceZ
r
T–X–Y Coupled Dynamics
S. Di Mitri - USPAS CO - Lecture_Th_13
WCSRW
n
WCSRWifyfxf
fnXXX
CB
XXX
CIIB
1111
0,
2
0,0
0
,,
2,
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Assume the CSR effect is dominated by the emission in the second half of the chicane (shorter bunch region).
Assume W effect is dominated by the random misalignment of acc. structures (over magnet offsets and spurious dispersion).
EXP.
EXP.
4-D Brightness
S. Di Mitri - USPAS CO - Lecture_Th_13
S. Di Mitri, PRST-AB 16,
050701 (2013)
20/06/2013 11
Compression factor fixed to reach 1.5kA and maximize Bn,f/CBn,0.
Fast analytical tool for guidance towards optimum working point (design) or brightness optimization (in already existing facilities).
DI M
ITR
I, P
RST
AB
1
6, 0
50
70
1 (
20
13
)
Brightness Optimization
S. Di Mitri - USPAS CO - Lecture_Th_13
S. Di Mitri, PRST-AB 16,
050701 (2013)
