Next Generation Gamma Diagnostics for the NIF (GCD/GEMS)

Transcription

1 Next Generation Gamma Diagnostics for the NIF (GCD/GEMS) National ICF Diagnostics WGM Hans W. Herrmann Los Alamos National Laboratory 10/6/15

2 NIF GCD Acknowledgements H.W. Herrmann, Y.H. Kim, A. McEvoy, A. Zylstra, N. Hoffman, M. Schmitt, C.S. Young, V. Fatherley, F.E. Lopez, J. Griego, J.A. Oertel, T. Sedillo, T. Archuleta, R. Aragonez, S.H. Batha, R. Leeper W. Stoeffl, J.A. Church, H. Khater, D. Sayre, A. Carpenter, J. Hernandez, J. Liebman, V. Glebov, W. Shmayda, D. Jacobs-Perkins, G. Pien T. Hilsabeck, J. Kilkenny C.J. Horsfield, M. Rubery, S. Gales, A. Leatherland J. Hares M. Gatu Johnson, J. Frenje, R. Petrasso J. Milnes E.K. Miller, R. Malone Slide 2

3 Next Generation Gamma Diagnostics will provide key burn parameters Gammas/neutron/(0.1 MeV bin) Gamma spectrum is full of information 1.E E E E E E E C(n,n'γ) Calculated NIF Spectrum Si Au Al Gamma- Ray Energy (MeV) Sup D(n,γ) D(t,γ 0 ) Enhanced Gas Cherenkov Detectors (GCD) for ρr Abl and Reaction Histories Super GCD: High Sensitivity (~200xGRH-6m) High Temporal Resolution (10 ps goal, ~10x faster than GRH-6m) Compton Spectrometer for gamma spectral measurements Sup GEMS: Energy Resolution: ΔE/E 5% Energy Range: E 0 ±33% within 2-25 MeV Temporal response < 1.5 ns Viable at Y DTn 5e14 National Diagnostic Plan s Transformative Diagnostics IFSA, G. Rochau We.S.4

4 Thresholded measurements are made with Gas Cherenkov Detectors (GCD) 1. Converts MeV γ-rays to UV/Visible photons for easy detection DT Implosion Fusion γ s 0.2 m from TCC γ-e - Converter v e c Relativistic Electron 2. Variable Energy Thresholding Threshold Eγ (MeV) SF 6 CO 2 DT-γ v e >c/n 3.0 MeV Threshold Cherenkov Radiation Index of refraction: n > 1 Pressurized Gas ( 400 psia) 200 psig limit Normalised Counts Pressure (psia) Cassegrainian Optics PMT 3. Fast Cherenkov Time Response GCD Impluse Resposne (CO2 at 100 psi = 6.3 MeV threshold) fwhm = 11 ps Time (ns)

5 Gas Cherenkov Detectors have been in operations at OMEGA & NIF for many years OMEGA-60 NIF MZ GRH-2m GRH-6m 2ω fidu MZ TCC 3 GCDs (20cm), 1 GRH (187cm) 4 GRHs (607 cm) Existing NIF GRH-6m has limited sensitivity due to large standoff distance à Bringing GCD to NIF

6 Phase I - GCD-3 in 3.9m Well with Photek Photodiode (~ 60 ps) New GCD Carrier Support Assembly (CSA) NIF Chamber Existing GCD-3 Existing 3.9m Well Physics: Improved temporal resolution for 12 C(n,n γ) Ø Diagnosis of stagnation & mix for carbon-based ablators Ø Background evaluation for Super GCD design Ø Test bed for fast optical detectors

7 Goal: resolve 12 Cγ and Hohl/TMP gammas to reduce uncertainty in carbon-based ablator ρr (CH & HDC) 2.0E E E E- 03 Notional GCD 2.9 MeV Threshold (a.u.) 1.0E E E E E E E E E E E E E E E E- 04 FWHM = ps ps ps i.e. Comparable GCD-3 Super Impulse GCD w/ PD w/ to & near today s BW~75ps PD-PMT perfect HiFoot ~10ps, recording Gas Cell ~30ps, & BW~40ps 0.0E Total 12Cg Hohl/TMP t (ns) Convolution w/ Gaussian representing convolution of: 1) Reaction History (currently ~125 ps) 2) Gas Cell IRF 2.9 MeV) 3) Recording System IRF (currently ~100 ps) Current implosions total FWHM ~150 ps à ρr Uncertainty ~30% GCD-3 w/ PD designed for ~100 ps à ρr Uncertainty ~15% Super GCD w/ PD-PMT for ~50 ps à ρr Uncertainty <10% Slide 7

8 Burn Widths are expected to narrow as implosion performance improves (i.e., approach 1D) 1D Ice vs. Liquid Layer Burn History Liquid BW < 100 ps expected Ice Ice layers = high CR à diverge from 1D LANL Wetted Foam (WF) low-cr targets expected to approach 1D performance R. Olson Ice Liquid Slide 8

9 Implementing new High-Bandwidth, Low-Gain Signal recording Recording Bandwidth Goals: >10 GHZ (i.e., 35 ps Rise Time) 8 GHz w/ 11x amplifier (for Y DTn <1e16) Photodiode with unity gain Simply a Photek PMT w/o the MCP (1 cm cathode) New anode mask mitigates ring irreproducibility New Mach Zehnder network design New low-v π MZ by Covega New dc-coupled PhotoReceivers to avoid previous GRH PR issues Photodiode IRF fwhm = 55 ps RT 10%-90% = 34.8 ± 3.4 ps AWE

10 NIF-GCD3: Mechanical Systems Overview Carrier Support Assembly (CSA) Weight:480 lbs CSA Alignment Fixture Weight:180 lbs GCD3 Detector Weight:205 lbs NIF Port D33 (3.9m Well) CSA Rigging Fixture Weight:295 lbs NIF FDR completed on 8/27/15, Operational by Spring 2016

11 Gamma detectors at NIF have to contend with backgrounds from: LPI x-rays from gas-filled hohlraums Prompt γ scattering background 12 Cγ NIF/OMEGA = 37 LPI NIF 12 Cγ DTγ OMEGA ρr (mg/cm 2 ) OMEGA NIF 12 C DT

12 OMEGA GCD-3 precursor used as basis for estimating LPI x-ray & Prompt Gamma backgrounds at NIF Direct GCD-3 vs GCD-1 comparison at 100 psia CO 2 2.5E- 02 Normalized Signal (V/(Gain*QE*Atten)) 2.0E E E E E+00 precursors GCD1 GCD3-5.0E Time rel. to BT (ns) GCD-3 has earlier precursor and cleaner return to baseline (faster response due to PMT110 vs 210)

13 GCD-3 signals expected to be above background Hevimet Tungsten Shielding MCNP Simulations* Chevrons Al Gunite MeV 3.9m Well 8MeV Prompt bkgd LPI bkgd Ø Existing Shielding adequate for OMEGA Ø ~200 lbs Added Shielding for 3.9m Well Ø LPI x-ray bkgd easily shielded Ø Prompt γ bkgd may be significant (SNR~3) in worst case *MCNP by H. Khater & S. Sitaraman Super GCD to mitigate Prompt bkgds for Reaction History Measurements Slide 13

14 Phase II - Pulse-Dilation PMT (FY16-FY17) B Anode T. Hilsabeck Th.Po.12 Physics: Improved Reaction History (RH) at high yield (~10ps at >1e15) Ø Accurate GBT/GBW at Burn Width <100 ps fwhm Ø NIC BW~175ps, HiFoot BW~125ps, Ignition BW ~10 ps expected Ø LANL Wetted Foam low-cr targets expect BW <100 ps Ø Non-Gaussian features (e.g., skewness, shock inflections, ) Ø Aid in exploration of Mix & Alpha Heating

15 Phase III - (FY16-FY18) Measure RH at low yield Enhanced Shielding Super GCD (100 lb GCD-3 à 275 lb Super GCD) - Improved gas cell temporal response for PD-PMT Get detector in closer (DIM or TANDM) Yields as low as 5e11 DTn measurable From (cm) To (cm) Sensitivity Increase ~2x ~5x ~25x Physics: Ø Initial shock yield timing Ø D 3 He Symcap (Y D3He-p 1e12, BR=1.2e-4 γ/p) Ø LANL s MARBLE Mix Campaign Ø CD/HT Mixcap (Y DT-n 1e12, BR=4.2e-5 γ/n) "Minimum DT Yield Required" 1.E+14 1.E+13 1.E+12 1.E+11 Y min ~ r cm 150 cm DTγ at 10 MeV Threshold 20 cm Distance from TCC to GCD nose (cm) ACCEPT simulations, C.S. Young

16 Time-resolved, Separated Reactant, Mix experiments will be made possible with HT gammas FY16 shot days at OMEGA: THD & HKMix Requires high-sensitivity for low-yield à Super GCD in close 1µm CD M. Schmitt Th.O.2.4 CH HT DT-γ ~16 MeV γ/n/(0.1 MeV bin) 1.E E E E E- 08 D(t,γ 0 ) 8 MeV 10 MeV 12 MeV 14 MeV Gamma- Ray Energy (MeV) H(t,γ) GRH Sensitivity (Ch_ph/inc_γ) HT-γ ~20 MeV 16

17 Low Energy Threshold (~ 2 MeV) enables new mission space 20 New gamma-ray detection too dim for GRH Threshold Eγ (MeV) GCD-1 (CO2) 6.3 MeV GCD-3 (C2F6) too low E for GCD-1 Ø 16 O(n,n γ) at 6.1 MeV (SiO 2 ρr) Ø 13 C(d ko,n) 14 N* at 5.69 MeV Ø 9 Be(α,n) 12 C* at 4.44 MeV Ø 9 Be(d ko,n) 10 B* 3.4 MeV Mix 1.8 MeV Pressure (psia) Ø 10 B(d ko,n) 11 C* at ~7 MeV Ø HD-γ at 5.5 MeV (MIT Zylstra PhD) Discovery Science Ø T 3 He-γ at 15.8 MeV Gatu-Johnson (MIT) Slide 17

18 NIF GCD Gantt Chart GCD Plan - 10/1/15 Updated Plan FY2016 FY2017 FY2018 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Phase 1 - Field GCD in 3.9m well MZ Elect D IQ OQ'd Installed D D Phase 2a - Pulse Dilation (PD) PMT Development Phase 2b - Field GCD w/pd- PMT in 3.9m well D Contract Placed D Prototype, CDR Production D Unit D FDR PD- LLNL Electronics D IQ OQ'd D Phase 2c - Automatic Gas Handling for 3.9m well D FDR D OQ'd Phase 3a - Develope and field Super GCD in 3.9m well CDR FDR D D Super OQ'd Phase 3b - Field GCD & Super GCD * in TANDM CART CDR D FDR GCD OQ'd Super GCD OQ'd * Baseline plan assumes MZ electronics external to TANDM GEMS FY18-FY20

19 Gamma-to-Electron Magnetic Spectrometer (GEMS) to provide true energy resolution γ-rays Compton electrons coil γ-to-e - Compton converter 4.4 MeV detector 10 to 20 MeV (3 to 6 MeV) detector plane 19

20 Gamma-to-Electron Spectrometer (GEMS) to provide true energy resolution x DT 10 g/n/mev ID Cryo-layered DD ExplPusher D(n,γ) 12 C(n,γ) 12 C(n,γ) 0 Difference Energy (MeV) Slide 20

21 Gamma Spectroscopy will be an enabling technology for NIF GEMS (Gamma-to-Electron Magnetic Spectrometer) Total Yield (no Total Yield measurement currently exists!) D(t,γ 0 ) Total Down Scatter Fraction (TDSF) when combined w/ primary Y n 4π Global Fuel ρr (Fuel ρr currently line-of-sight) D(n,γ) Ablator ρr (reduced uncertainty relative to GRH) 12 C(n,n γ) Mix studies (e.g., 9 Be(α,nγ), 13 C(d,nγ), 11 B(d,nγ) ) Neutron Interactions on materials (i.e., pucks) Astrophysical studies (e.g., s & r-processes) Analyzing Electro- Magnet e - Graphite Collimator Detector Array (Cherenkov to PMT) Calculated NIF Spectrum X- ray Filter & Collimator (2m from TCC) Reentrant Tube Electron Beam Port Cover Support Structure (modified from MRS) γ- to- e - Converter Sweeper Magnet NIF CDR held in July 2013 Energy Resolution: ΔE/E 5% Energy Range: E 0 ±33% within 2-25 MeV Temporal response < 1.5 ns Viable at Y DTn 5e14

22 Next Generation Gamma Diagnostics will provide key burn parameters Gamma spectrum is full of information Calculated NIF Spectrum Compton Spectrometer for gamma spectral measurements Enhanced Gas Cherenkov Detectors for Reaction and ρr Abl Histories Sup Sup Super GCD: High Sensitivity (~200xGRH-6m) High Temporal Resolution (10 ps goal, ~10x faster than GRH-6m) GEMS: Energy Resolution: ΔE/E 5% Energy Range: E 0 ±33% within 2-25 MeV Temporal response < 1.5 ns Viable at Y DTn 5e14

23 Backups 23

24 Key Capability Improvements enable Super GCD to meet its goals Improved temporal resolution ~60 ps w/ Photodiode (but unity gain) ~10 ps with Time Dilation-PMT (further development required) Ø Current GRH/GCDs limited by MCP PMT to ~100 ps Increased sensitivity (at 20 cm from TCC): >20x sensitivity of OMEGA GRH-2m at fixed threshold achieved >200x sensitivity of NIF GRH-6m at fixed threshold Low threshold (additional sensitivity and new spectral window) As low as 1.8 MeV with 400 psia C 2 F 6 Ø GCD-1 limited to 6.3 MeV Ø GRH limited to 2.9 MeV Super GCD is at a High Technical Readiness for NIF

25 Super GCD (Gas Cherenkov Detector) will enable enhanced Gamma Ray Detection at NIF with: 1) High Sensitivity (~200xGRH-6m) 2) High Temporal Resolution (~10 ps for DTγ vs 100 ps for GRH-6m) 3) Low Energy Threshold (1.8 MeV vs 2.9 MeV for GRH-6m) Missions: TN Burn: Reaction History CH ρr History Mix measurements - CD Mixcap - Dark Mix Discovery Science: Astrophysical s-process Big Bang Nucleosynthesis Stellar pp Fusion Chain Z Global Security: Improved cross sections for forensic signatures puck implosion N

26 The Prompt γ-ray Energy Spectrum from Indirect-Drive, Cryo- Layered Implosions is complicated and never directly measured! ~1 D + T 5 n (14.1 MeV ) + α (3.5 MeV) He* ~ 4e 5 5 He + γ (16.75MeV ) n +α Gammas/neutron/bin) 1.E E E E E E C(n,n γ) Capsule gammas nearly simultaneous w/ DT Si Au Al 12 C(n,γ) γ 1 D(n,γ) DT Fusion γ 0 12 C(n,γ) 1.E- 08 Assumptions: Ø BR(γ/n) = 4.2e-5 γ/n Ø γ 1 /γ 0 = 2.3 Ø ρr 12C = 0.5 g/cm 2 Ø ρr DT = 1.5 g/cm Gamma- Ray Energy (MeV) Hohlraum/TMP gammas delayed ~100 ps 26

27 Thresholded Cherenkov detectors provide high temporal bandwidth at cost of spectral resolution Gammas/neutron/bin) 1.E E E E E E C(n,n γ) DT Fusion Threshold (MeV) E+00 1.E E E E- 04 GRH Sensitivity (Ch_ph/Inc_γ) 1.E Gamma- Ray Energy (MeV) 1.E

28 Three Rigging Operations (2 of which are one-time only) 1) Alignment Fixture 3) Gas Cell Beech Crane ATI Crane 2) Carrier Support Assembly (CSA) ATI Crane

29 GCD3 photocathode is exposed to 1 st Wall scattering Collimator face at 3.967m - Only have ~60mm (~2.4 ) available to move forward w/in 3.9m well - In addition, GCD can move forward ~4cm (1.6 ) - Total of ~4 available to move forward w/in 3.9m Well Slide 29

30 Would need to move GCD3 forward ~½ ft to shield 1 st Wall with bat ears (another few inches to take advantage of external W cylinder) 8.8cm/0.66 =13.33 cm per 8.8cm 1.18 = 15.7 cm = 6.2 inches Slide 30