17 th hapl meeting washington, dc october 30, 2007 naval research laboratory plasma physics division...
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17th HAPL MeetingWashington, DCOctober 30, 2007
Naval Research LaboratoryPlasma Physics Division
Washington, DC
Work supported by DOE/NNSA/DP
Optical System and staging of the Electra KrF laser facility
NRL M. Wolford
M. MyersJ. SethianJ. Giuliani
Commonwealth Tech
F. Hegeler
RSIP. Burns
SAIC R. Jaynes
LPX 305 i
Input 0.5 J10 cm x 10 cm
Cylindrical lens Pair
Telescope
1 cm x 3 cm
3 cm x 3 cm
OutputInput
BG 28
LA Vision
Improved Near Field Measurements since last HAPL Meeting
80% Ar, 0.3% F2
0.0
5.0
10.0
15.0
20.0
25.0
30.0
8 12 16 20Pressure (psi)
Las
er O
utp
ut
(J)
Orestes 0.5 J Input
Measured Input ~0.5 J
Orestes 0.7 J Input
Measured Input 0.6 J
Single Beam Electra Pre-Amplifier Yield
Voltage
OutputInput
64.8 ns
-50
0
50
100
150
200
250
300
350
-40 -20 0 20 40 60 80 100 120 140
Time (ns)
Vo
ltag
e (k
eV)
Po
wer
(10
0 M
W)
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Inte
nsi
ty (
arb
.)
Diode VoltageDiode PowerOutputInput
Single Beam Timing Between Laser Input, Laser Output and Electron Beam (10 J)
-1
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140
Time (ns)
Inte
ns
ity (
arb
.)
1 (-36.3 ns) 3.8 J
2 (1.3 ns) 10.0 J
3 (21.5 ns) 15.7 J
4 (40.7 ns) 20.0 J
5 (64.8 ns) 10.0 J
6 (88.0 ns) 2.9 J
Power (10 GW)
1
2
3
4
5
6
-40 -20 0 20 40 60 80 100 120 140
1 2 3 4 56
Input
Output
Single Beam Output Time Dependent Intensity
0
5
10
15
20
25
-50 0 50 100 150Input Time (ns)
En
erg
y (J
)
80% Ar, 0.3% F2@ 16 psi80%Ar, 0.3% F2@ 18 psiOrestes 16 psi
Orestes 18 psi
-30 -10 10 30 50 70 90Time (ns)
Cause of Discrepancy
Single Beam Pre-Amplifier Yield Function of Input Timing
LPX
PLCC
Cylindrical Optics6 m Nike Lens
BeamsplitterCalorimeter
Photodiode Combo
770 mJ Laser Input Laser Beam separation ~26 ns
00.10.20.30.40.50.60.70.80.9
1
-5.0E-08 0.0E+00 5.0E-08 1.0E-07 1.5E-07Time (s)
Vo
lts
Beam 1 ~ 373 mJBeam 2 ~ 397 mJ
PD 2PD1
Two Beam Angularly Multiplex Preamplifier
Calorimeter Data
-1
0
1
2
3
4
5
6
7
0 25 50 75 100
Time (ns)
Inte
ns
ity
25 J Laser Output
300 mJ Laser Input Laser Beam separation ~26 ns
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 20 40 60 80 100Time (ns)
Vo
lts
Beam 1 Beam 2
8.1 cm 7.6 cm
9.0 cm 9.7 cm
25 J Output of Two Beam Angularly Multiplex Preamplifier
Dimensions
LPX
Pre-AMPMain AMP
Electra Laser System
Calorimeter
Photodiode (PDM)
Photodiode (PDTarget)
42 m
-0.5
0
0.5
1
1.5
2
2.5
3
600 650 700 750 800 850
Time (ns)
Inte
nsi
ty (
arb
.)
PDM (452 J)
Pdtarget (452 J)
PDM1 2
3 4
5 6
Pdtarget
0
100
200
300
400
500
-1 0 1 2 3 4 5 6
Time (s)E
ner
gy
(J)
Big Calorimeter33 x 33 cm2 Calorimeter
Nike Calorimeters18 x 18 cm2 Calorimeters
Sum
Full Laser System 452 J Single Shot Yield
Full Laser System Laser Yield Depends on Timing Between LPX, Pre Amplifier and Main Amplifier
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 50 100 150 200 250Time (ns)
Inte
nsi
ty (
arb
.)
452 J (PDM)237 J (PDM)
The Difference if one or both beams are amplified in Pre-amplifier
Timing Discrepancy Between Amplifiers
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-50 0 50 100 150 200Time (ns)
Inte
ns
ity
(a
rb.)
Shot 1 (PDM)Shot 2 (PDM)Shot 3 (PDM)Shot 4 (PDM)Shot 5 (PDM)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300
Time (ns)
Inte
nsi
ty (
arb
.)
Shot 1 (406 J)
Shot 2 (365 J)
Shot 3 (412 J)
Shot 4 (268 J)
Shot 5 (134 J)
PDM1 2
3 4
5 6
PDTarget
Full Laser System Yield 1.585 kJ in One Second 5 Hz Burst
Single Pass Double Pass
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-50 0 50 100 150 200Time (ns)
Inte
ns
ity
(a
rb.)
Shot 1 (PDM)Shot 2 (PDM)Shot 3 (PDM)Shot 4 (PDM)Shot 5 (PDM)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300
Time (ns)
Inte
nsi
ty (
arb
.)
Shot 1 (406 J)
Shot 2 (365 J)
Shot 3 (412 J)
Shot 4 (268 J)
Shot 5 (134 J)
Single Pass Double Pass
Why laser Yield is Decreasing with Shot #?
Observation: Larger Percentage Laser Intensity Decrease was observed after one pass than double pass
Probable Cause: A declining input laser intensity into the main amplifier
Single Shot 5 shot Rep-Rate Burst
Cross Hairs for Scale
Near Field (7m) Beam ProfileSuggests increase in Phase Aberration is the cause for the drop in laser energy for
the Electra Laser System
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-20 0 20 40 60 80 100
time (ns)
ampl
itude
(ar
b. u
nits
)
1st shot
5th shot
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 50 100 150 200 250
time (ns)
ph
oto
dio
de
amp
litu
de
(V) shot 1
shot 100
shot 200
shot 300
shot 400
shot 500
500 shots @ 5 Hz
5 shots @ 5 Hz
Pre-amp without gas recirculator
Main-amp with gas
recirculator
Pre-amplifier Needs Recirculator For Rep-Rate Operation
0
500
1000
1500
2000
2500
3000
-2 0 2 4 6 8 10 12Time (seconds)
To
tal L
aser
Yie
ld (
J)Electra Laser System 2.5 kJ 2 second burst @ 5 Hz
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 50 100 150 200 250
Time (ns)
Inte
ns
ity
(a
rb.)
PDM_1PDM_2PDM_3PDM_4PDM_5PDM_6PDM_7PDM_8PDM_9PDM_10
All Components 5 Hz operational for longer bursts
Again, Low Yield for later shots due to Pre-AmpPhase Aberrations, will be corrected with Recirculator
Calorimeter Response
1)Pre-Amp Recirculator (Design Complete) (For Beam Quality, Consistent Rep-Rate Output)
2)Improved Coupling from Pre-Amp to Main Amp
3)Improved timing control, Reduced Jitter (improvement already made)
4)Increase and Improve Diagnostics for KrF Code Comparison
5)Strip Cathode for Pre-Amp (Increased Energy Deposition in laser gas by ~25%)
On Going Improvements in Laser System Since Measurements were made
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