sparc operation in seeded and chirped...
TRANSCRIPT
SPARC operation in seeded and
chirped mode
Luca Giannessi
ENEA C.R. Frascati
On behalf of the SPARC collaboration
32° International FEL Conference - Hilton Malmo City, Sweden, August 23-27 2010
Outline
• SASE FEL operation with a chirped beam– Lasing with chirped beam combined with tapered
undulator
• Seeded FEL operation– Seeded amplifier with the generation of high order
harmonics
– Cascaded FEL operating above saturation 400nm -> 200nm
– Cascaded FEL seeded with harmonics generated in gas
SASE with chirped & compressed beam
Compensation of the chirp with UM Taper
E. L. Saldin, E. A. Schneidmiller, and M.V. Yurkov, Self-amplified spontaneous emission FEL with energy-
chirped electron beam and its application for generation of attosecond x-ray pulses, PHYSICAL REVIEW
SPECIAL TOPICS - ACCELERATORS AND BEAMS 9, 050702 (2006)
• Compression with “Velocity Bunching”
– High peak current (up to 380A)
• Compression with “Velocity Bunching”
– High peak current (up to 380A)
• Compression with “Velocity Bunching”
– High peak current (up to 380A)
“Reconstruction” by D. Filippetto
Slippage length ~
e-bunch length
Projected r.m.s.
Energy spread ~ 1%
Strong chirp / energy spread in the longitudinal phase space
• Compression with “Velocity Bunching”
– High peak current (up to 380A)
Undulator
Resonance condition is a function of
Beam energy (chirp) / Undulator K
(untapered)
z
Radiation slips off resonance while
propagating along the undulator
δω
Initial
resonance
condition
ω
Wavelength range 45 nm
Spectr
om
ete
r slit
(vert
ical posititio
n)
Central Wavelength 540 nm
Spectrum
Average over 100 spectraEnergy 8 uJ (max 38 uJ)Rel Linewidth 1.6% rms
z
Resonance
condition
ω
u
u
ur
c
K
2
21
22
2
00)( sss
00)( zzKzKK k
Chirp
Taper
Resonance is maintained by tuning the
undulator taper
Compensation with Undulator taper
Average over 100 spectra:
Energy 140 uJ (max 380 uJ)
Rel Linewidth 0.8% rms
Single cooperation length observed in many spectra
(as the one shown above)
Average energy per pulse 18 times higher !!!
… in a narrower bandwidth (~1/2)
To see more: Poster sessions
ID: 1491 - TUPB18 FEL Experiments at SPARC
ID: 1642 - MOPB16 Energy Phase Correlation and FEL Efficiency
45 nm
Seeded Operation
Seed
FEL Amplifier
FEL Harmonic Generation
Seed 1
Modulator Radiator
2= 1/n, n=2
• Seed Sources:– 266 nm & 160 nm generated in gas
– 400 nm in BBO crystal (high seed energy)
• Cascaded FEL tested with both seed configurations
Direct seeding above saturation
Expected very efficient generation of high order harmonicsL. Giannessi, P. Musumeci, S. Spampinati, J. Appl. Phys. 98, 043110 (2005)
Seed Energy < 0.5 uJ
Direct seeding above saturation
Expected very efficient generation of high order harmonicsL. Giannessi, P. Musumeci, S. Spampinati, J. Appl. Phys. 98, 043110 (2005)
Seed Energy < 0.5 uJ
~ 0.7 uJ
Direct seeding above saturation
Expected very efficient generation of high order harmonicsL. Giannessi, P. Musumeci, S. Spampinati, J. Appl. Phys. 98, 043110 (2005)
Seed Energy < 0.5 uJ
~ 0.7 uJ
~ 3 uJ
Direct seeding above saturation
Expected very efficient generation of high order harmonicsL. Giannessi, P. Musumeci, S. Spampinati, J. Appl. Phys. 98, 043110 (2005)
385 390 395 400 405 410 415
4
6
8
5E8
7,25E8
9,5E8
1,175E9
1,4E9
1,625E9
1,85E9
2,075E9
2,3E9
2,525E9
2,75E9
2,975E9
3,2E9
3,425E9
3,65E9
3,875E9
4,1E9
4,325E9
4,55E9
4,775E9
5E9
lamda
Y Axis
Title
GENESIS
Simulation
Seed Energy < 0.5 uJ
~ 0.7 uJ
~ 3 uJ
~ 9 uJ
Harmonics down to 37 nm
Observation of 11° harmonic at 37nm
11h 10h 9h 8h 7h 6h 5h 4h 3h 2h 1h
To see more:
Poster session ID: 1491 - TUPB18
FEL Experiments at SPARC
Measured energy per pulse,
spot size & and bandwidth
of the first 11° harmonics
Cascaded configurations – Seed@400nm
Seed 1= 400nm
Modulator Radiator
2= 200 nm
Indication of saturation @200 nm
SPECTRUM @ 200 nm
Indication of saturation at 200nm
0.6 0.8 1 1.2 1.40
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Spot (rms mm)
Ener
gy (
nJ)
Correlation Energy – Spot size
0.3 0.35 0.4 0.450
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Rel. Linewidth (%)
Ener
gy (
nJ)
Correlation Energy – Linewidth
199.3 199.4 199.5 199.6 199.7 199.80
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Mean Wavelength (nm)
Ener
gy (
nJ)
Redshift
0.6 0.8 1 1.2 1.40
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Spot (rms mm)
Ener
gy (
nJ)
Correlation Energy – Spot size
0.3 0.35 0.4 0.450
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Rel. Linewidth (%)
Ener
gy (
nJ)
Correlation Energy – Linewidth
199.3 199.4 199.5 199.6 199.7 199.80
5 103
1 104
1.5 104
2 104
0
50
100
150
200
Total
Slit
Mean Wavelength (nm)
Ener
gy (
nJ)
Redshift
3° harmonic of the radiator
62 64 66 68
Wavelength (nm)
Inte
nsi
ty (
a.u.) Spectrum averaged over 30 shotsmax ~ 100 nJ,
average 30 nJ
0 1 2 3 4 50
10
20
30
Rel. Linewidth (%)
Pro
bab
ilit
y (
%)
FEL seeded with
harmonics generated in gas
Seed 266nm 1
Modulator Radiator
2= 133 nm
50 nJ 5-4-3 UM tuned @ 266 nm – 1-2-3 UM tuned @133 nm
Seed @ 266 nm → 133 nm
Studied the cascade changing the number of modulators/radiators
Direct seeding @ 160 nm
0 500 1 103
1.5 103
2 103
0
10
20
30
40
Energy (nJ)
Pro
bab
ility (
%)
Poster sessions
ID: 1491 - TUPB18 FEL Experiments at SPARC
ID: 1642 - MOPB16 Energy Phase Correlation and FEL Efficiency
Thank you !!!