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Shots, shot and more shots on OMEGA allows diagnostics and targets development, opening new
areas of science
Presentation to
OMEGA Laser User Group April 27, 2011
Joe Kilkenny
NIF Diagnostic Leader &
General Atomics V. P.
This is an exciting time to be doing High Energy Density Physics: US has 3 forefront facilities
As well an important role for OMEGA is to develop techniques / diagnostics for NIF
Drivers
Advances in High Energy Density Physics Require:
Given a driver, innovation in targets and diagnostics drive new science
Theory
Targets
Diagnostics
Laser
Most of the > 40 NIF diagnostics were developed on Nova, OMEGA or NTS
4
FABS31
on NIF
Energetics
Energetics diagnostics. Full Aperture Backscatter
Gated
X-ray
Detector
Capsule
Capsule diagnostics,
developed on OMEGA,
Ignition
UGT experience, development
on OMEGA with neutrons
NIF, OMEGA and Z are generational machines
-diagnostics will continuously evolve
NIF’s ignition diagnostics measuring: Yield, Areal density ( R), Ion Temperature (Tion), Bang time, burn duration and Shape developed on OMEGA
Diagnostic Primary purpose Acronym
Zirconium Nuclear Activation Yield Well NADS
Copper Nuclear Activation Yield NAD 20
Magnetic Recoil Spectrometer Yield, R, Tion MRS
Gamma Reaction History N bang time, burn duration
GRH
Neutron Time of Flight
20m – Equator Tion , R NTOF_20E
20m - Alcove Tion , R NTOF_20A
Neutron Bangtime N bang time NTOF_BT
DT – high yield Yield > 5e13 NTOF4_DTHI
DT – Low yield Yield < 5e13 NTOF4_DTLO
Hardened Gated X-ray Imager (hGXI)
X-ray Shape, X-ray bang time
hGXI
Neutron Imaging (NIS) Neutron shape NIS
Why measure attributes different ways?
MacKinnon—NIC Technical Review, February 23-25, 2011 6 NIF-02211-21072s2.ppt
Complementary redundant diagnostics are essential for the scientific method
• Karl Popper, Hutchinson Press, 1959: cannot prove a theory (measurement) is right, can prove it is wrong - by test ( comparison with other diagnostics
NIF-1209-17998.ppt Kilkenny, NIC Review, December 9–11, 2009 6
• Down Scatter Fraction (DSF): measure by NToF and Magnetic Recoil Spectrometer • R: measure with NToF, MRS, Radchem and by ARC • Hot spot T measured by x-rays and neutron emission
Falsifiability and Testability : Hypotheses are nets: only he who casts will catch
To make a contribution to NIF diagnostics you don’t have to work at a large national Laboratory
MacKinnon—NIC Technical Review, February 23-25, 2011 7 NIF-02211-21072s2.ppt
LLNL – FABS,NBI – Dante I & II – VISAR – DISC – RAGS – hGXI – ARIANE – DIXI – NAD
AWE – FFLEX
LANL – GXD – burn – Rad. Chem. II – n imaging
SNL – SPIDER – DISC – NAD (Cu) – NToF – RAGS
Universities develop valuable niches: MIT- CR39, U of M targets, Imperial College- high speed electronics.
NSTec – Calibration – NToF
LBNL – Calibration – Rad. Chem.
CEA – N imaging
Duke – Calib.
MIT – MRS – WRF – PTOF
LLE – NToF – 4 fidu system – MRS, NADS – SPBT – HEXRS – PSBT
U of M. – HEMPI
Pat McKenty’s polar direct drive exploding pushers verify the performance of the ignition diagnostics
MacKinnon—NIC Technical Review, February 23-25, 2011 8
NIF-02211-21072s2.ppt
Yn: Magnetic Recoil Spectrometer (MRS)
Yn: Neutron Activation (NAD, Zr)
Zr
Yn: Neutron Activation (NAD, Cu)
Cu
Exploding pushers:Direct drive – 125kJIsotropic Yield ~ 2e14Low R < 20mg/cm2
Polar direct drive platform designed, developed at LLE
1.5mm diam. Capsule w/ 10 atm 50:50 DT fill
Low R provides ideal, low background for yield and downscatter diagnostics
Yield: Zr Cu and Zr activation measures yield for DT shots to absolute accuracy of ± 7% : BUT how do we know it is right?
MacKinnon—NIC Technical Review, February 23-25, 2011 9 NIF-02211-21072s2.ppt
Exp.Pusher: Raw Data, 8.7mm sample
Co
un
ts
24 hours counting
89Zr
1.0 3.5
8.7
3 samples with
different thickness
Placed in a well 4.5m from TCC
Neutron energy (MeV)
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30
In-115(n,n')In-115m
Nb-93(n,2n)Nb-92m
Zr-90(n,2n)Zr-89C-12(n,2n)C-11
Cu-63(n,2n)Cu-62
90Zr(n,2n) 89Zr (t1/2=3.3 d)
63Cu(n,2n) 62Cu (t1/2=9.74 m)
Cro
ss s
ecti
on
(b
)
Activation Foil cross sections 14 MeV n
10 MeV n
Y = 2.3 x 1014 ± 7 %
Shot N
101030
Yield: Copper activation has an absolute accuracy of ±10%- maybe
MacKinnon—NIC Technical Review, February 23-25, 2011 10 NIF-02211-21072s2.ppt
Y = 2.5 x 1014 ± 10 %
Copper Decay curve N101030 – Exp pusher
0
100
200
300
400
500
600
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0
Co
un
ts/M
inu
teTime (minutes)
9.5 mm Cu at 29 m
1.0 mm Cu at 19 m
Copper sampling yield on equator and in neutron alcove
Uncertainty Estimates Error±1
Detector efficiency & Gamma-ray self-shielding
8.6 %
Cu cross section uncertainty 1.3 %Position uncertainty (awaiting measurements) 0.1 %
Scatter/absorption from Al and W attenuators 5.0 %
TOTAL SYSTEMATIC 10.0 %
Statistical 2.5 %
1mm Cu
1mm Cu
9.5mm Cu
MacKinnon—NIC Technical Review, February 23-25, 2011 11 NIF-02211-21072s2.ppt
The NIF magnetic recoil spectrometer (MRS) was developed on OMEGA by MIT and LLE
Kilkenny, NIC Review, December 9–11, 2009 11NIF-1209-17998.ppt
• MRS has measured rr on OMEGA
• Action items were focused on transfer
of instrument technology to NIF
Yield: The MRS has been designed and implemented for simultaneous measurements of R, Y1n and Tion
MacKinnon—NIC Technical Review, February 23-25, 2011 12 NIF-02211-21072s2.ppt
Low-Res tf = 275 μm
Med-Res tf = 125 μm
CR-39 “ironing board”
Rf = 26 cm
Ra = 570 cm
Aa = 20 cm2
Accuracy requirement for the MRS absolute yield measurement < 10% for Y1n > 1014
n
d+
Is the CR-39 “ironing board” radioactive?
MacKinnon—NIC Technical Review, February 23-25, 2011 13 NIF-02211-21072s2.ppt
NIF WRF proton spectrometer used in 2009, improvements for 2010
CR39 used in Wedge Range Filter ( WRF) after major OMEGA/MIT development on MIT accelerator
NIF WRF proton spectrometer used in 2009, improvements for 2010
East /West summit on Good Friday 2011
Yield: MRS provides absolute primary yield to ± 5% accuracy: nd cross section and foil area uncertainty are largest components
MacKinnon—NIC Technical Review, February 23-25, 2011 14 NIF-02211-21072s2.ppt
MRS has different systematic errors from nuclear activation ( NAD)
MRS Spectrum for Pusher shot
Yield = 2.2e14 ± 5%
μ
Yield Error Budget
N101030
zero downscatter
Three independent Yn diagnostics ( Zr, Cu & MRS) gives 4% error in the weighted mean yield
MacKinnon—NIC Technical Review, February 23-25, 2011 15 NIF-02211-21072s2.ppt
So what?: surprisingly (at first) we found the OMEGA nTOF calibration did not transfer to NIF
MRS
Well NADS Zr
NADS 19m Cu
Neutron Yield
2.1 2.2 2.3 2.4 2.5 2.6 2.7 Yn x1014
N101030-0
02-9
99
Weighted mean yield = 2.3e14 ± 8.9e12 ( ± 3.9%) 2/ (n-1) = 0.9
Weighted
mean
R: Neutron downscatter measured from three different directions to minimize sampling errors due to directionality of scattered neutrons
MacKinnon—NIC Technical Review, February 23-25, 2011 16 NIF-02211-21072s2.ppt
20 m
dN
/dt
TOF [ns]
23ns
“Wilson
2E14”
Downscatter ratio (DSR*) technique
MRS - measure tracks in DSR region
MRS+ 2x NTOF20’s on 3 lines of sight
• LLE cal. • SNL, NsTEC cal.
• LLNL installation
NTOF – scattered neutrons in tail
Primaries 12-10MeV
DSN THD
* DSR = (10-12MeV) / (13-15MeV)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
410 420 430 440 450 460 470 480 490 500 510 520
neu
tro
ns/(
Yie
ld n
s)
Time (ns)
R: Down Scatter Ratio (DSR) by MRS and NToF20 are self consistent within the measurement error
MacKinnon—NIC Technical Review, February 23-25, 2011 17 NIF-02211-21072s2.ppt
• Background level from exploding pushers is reproducible • Shorter cables planned for NTOF20 will reduce uncertainty
Lower cable induced background levels by ~3x
NToF Signal clearly shows down scatter signal on all THD shots
MRS: DSR error < 10% for Yn >1e14 and .R ~ 1g/cm2
THD-3: DSR = 0.027 ± 0.005 THD-3: DSR = 0.024 ± 0.003
(N110201)
N110201
Exp pushers
50x signal
13 - 15 MeV 10 - 12 MeV
THD
Neutr
on/s
Area normalized
Bangtime: Gamma Reaction History (GRH) routinely measuring Bang Time (w/in 30 ps) and Burn Width (w/in 15 ps)
MacKinnon—NIC Technical Review, February 23-25, 2011 18 NIF-02211-21072s2.ppt
GRH-6m at (64,20) DT exploding pusher Data
No CO2
Exploding Pushr (N101212)
Deco
nvo
lved
Gau
ssia
n
Tim
ing
Sh
ot
Fit
(N
101029)
Bang time +/- 30 ps
Burn width +/- 15 ps
DT
0
Yie
ld R
ate
n/n
s)
0
5 1014
1 2 3 -1
Time (ns)
Bangtime agrees with NToFBT data to within 100 ps
3-10MeV GRH will be fielded on DT implosions for yield and 4.4MeV carbon (ablator density measurement)
• 4 Gas Cherenkov cells • Detectors installed with Ultra-fast MCP PMTs and optical Mach Zehnders
A new Particle Time of flight (pTOF) detector has been implemented for shock-bang and compression-bang time using D3He-protons and DD-neutrons, respectively
MacKinnon—NIC Technical Review, February 23-25, 2011 19 NIF-02211-21072s2.ppt
DIM (0,0) WRFs DIM (90,78) WRF + CVD
• Relative timing of shock and compression feature is constraint to implosion models
• Project led by MIT• Requires Exploding pusher to qualify
MIT
Particle bang time data DHe3 SYMCAP 1208
Proton Spectrum from WRF
Energy (MeV)
Pro
ton
s/ M
eV
• Compression BT = 21.2 ± 0.15 ns
NIF’s $20M Neutron Imaging System has begun performance qualification using McKenty’s exploding pushers
MacKinnon—NIC Technical Review, February 23-25, 2011 20 NIF-02211-21072s2.ppt
Signal: 7500 counts
pusher
Reconstructed Neutron Image Raw Image
NIS Pinhole array
Exploding pusher DATA
150 μm
Yield = 2e14
Compare to gated x-ray
Image
150 μm
MacKinnon—NIC Technical Review, February 23-25, 2011 21 NIF-02211-21072s2.ppt 4/27/11 MR 01-12-11 21
P. Volegov – NIS analysisR. Tommasini – hGXI analysis
Consistent with neutron hot spot inside x-ray emitting region ?
Remnant of Si pusher emits strongly in 6keV x-ray region
NIF s owl is skeptical without image registration
The best of times in HED!
22
• Innovative diagnostics allow advances in HED • New diagnostics require a significant number of development shots
• OMEGA users are playing a major role in development of NIF diagnostics
But what next ? Decadal innovation in diagnostics by new minds will allow us to fully exploit OMEGA, Z and NIF.
Think clever, think big!
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