Introduction
The MIT Accelerator for development of ICF diagnostics at OMEGA / OMEGA-EP and the NIF SBDs d + or 3 He +(2+) D or 3 He target Present MIT Graduate Students and the MIT Accelerator OLUG 21 (2 nd Annual Workshop, Wed-Fri, April 28 th -3 th, 21
Collaborators N. Sinenian, D.T. Casey, M. Manuel, H.G. Rinderknecht, M.J. Rosenberg, A. Zylstra, J.A. Frenje, F. H. Seguin, C.K. Li, R. A. Childs, and R. D. Petrasso Massachusetts Institute of Technology B. Felker, S. Friedrich Lawrence Livermore National Laboratory J. Kilkenny General Atomics V. Yu. Glebov and C. Sangster Laboratory for Laser Energetics, Univ. of Rochester R. Leeper, C. Ruiz Sandia National Laboratory
Summary The MIT accelerator generates fusion products relevant for three NIF nuclear diagnostics based on CR-39: DD-n yield diagnostic Wedge-range-filter Proton Spectrometer MRS Neutron Spectrometer It is currently used to support the development and calibration of new and existing diagnostics for use at OMEGA, OMEGA-EP and the NIF. F.H. Séguin et al., Rev. Sci Instrum 74, 975 (23). S. McDuffee et al., Rev. Sci Instrum 79, 4332 (28)
The MIT accelerator is capable of producing fusion products and beam ions relevant for ICF diagnostics development Ion beam
Fusion products produced by the accelerator
The accelerator is capable of producing several fusion products and beam ions Primary products (kinematics not included): D + D T (1.1 MeV) + p (3.2 MeV) D + D n (2.45 MeV) + 3 He (.82 MeV) D + 3 He a (3.6 MeV) + p (14.7 MeV) Beam ions: D + (<15 kev) 3 He + (<15 kev) 3 He 2+ (<3 kev)
# / bin [au] # / bin Radioactive sources and kinematic calculations are used to characterize the energy of the fusion products 1 8 6 226 Ra source (a-source) for instrument calibration 4.6 5.3 5.8 7.5 MeV 5 4 3 12 kev D + beam on 3 He DD-t (1. MeV) DD-p (3. MeV) 4 2 2 1 D 3 He-p (14.7 MeV) 2 4 Channel 5 1 15 2 MeV Fusion product rates up to ~1 7 /s are readily achieved
# / Bin #/ Bin Kinematic effects and ranging filters are exploited to provide fusion products with a large range of energies SBDs d + or 3 He 2+ BB-WRF proton spectrometers 6 5 4 3 2 D 3 He-p 1159 884 133 77 482 µm Al 1 Θ lab D or 3 He target Θ lab 7 6 5 4 3 2 5 1 15 MeV DD-p 72 66 51 31 6 µm Al 1 1 2 3 MeV
Primary Objectives
The objective with the accelerator is to design and characterize instruments for diagnosing ICF plasmas at OMEGA, OMEGA-EP ~24 feet Capsule diameter ~1 mm A direct-drive implosion 6 laser beams delivering 3 kj on capsule in ~1 ns Direct or indirect drive
and the National Ignition Facility (NIF) at LLNL ~6 feet Person Inside the NIF target chamber 192 Laser Beams delivering 1.8 MJ on capsule Indirect drive or direct drive First credible ignition experiments ~21 Cryogenic Hohlraum (length ~ 9 mm)
Diagnostic #1: CR-39-based neutron yield detector
Compact, CR-39 based DD-n detectors 5 cm 5cm Compact, CR-39 based DD-n detectors have been fielded on the NIF
The accelerator has been used to measure the CR-39 efficiency for detection of DD-neutrons at OMEGA and the NIF Shown here is detector package for both neutron and secondary proton measurements The detection efficiency determined from the accelerator is applied to OMEGA and NIF data J.A. Frenje et al., Rev. Sci. Instrum. 73 (22). F. H. Seguin, et al. (to be submitted) M. Manuel et al. (this session)
recoil proton tracks per bin, a.u. CR-39 has been exposed to known fluences of neutrons on the MIT accelerator recoil proton counts per bin, a. u. 5 um CH 2 proton multiplier 3MeV protons Front Side Back Side 6. 15 4. 1 2. 5.. 5. 1. 15. Y position, pixels 5 1 15 Y position, pixels Silicon barrier diodes (SBDs) were used to measure the associated particle fluence (3MeV protons)
Tracks per cm 2 per bin Recoil Proton Tracks per cm 2 per bin Detection efficiencies were determined for different yield processing techniques 2 16 12 8 Front top Front bottom Back 16 12 8 Front top - bottom Back - front bottom 4 4 5 1 15 2 25 5 1 15 2 25 Scaled Track Diameter (um) Scaled Track Diameter (um) Detection efficiencies of DD-n of order 1-4 have been determined
Diagnostic #2: Wedge-Range-Filter (WRF) Proton Spectrometer
WRF proton spectrometers have been fielded in the polar and 9-45 DIM on the NIF Aluminum WRFs
The accelerator has been used to calibrate WRF spectrometers for the measurements of D-3He protons at OMEGA and the NIF Aluminum (left) and Zirconia (right) WRFs have been used on the recent NIF campaign F.H. Séguin et al., Rev. Sci Instrum 74, 975 (23).
Yield / MeV The WRF spectrometers have been used at OMEGA and the NIF for diagnosing ρr and ρr asymmetries in a wide range of implosions through measurements of D-3He protons 3 [ 1 8 ] D + 3 He a + p (14.7 MeV) NIF shot N91123 2 WRF spectrometers 2 Compression Shock 5 cm 1 6 8 1 12 14 16 MeV Birth energy NIF Implosions were viewed through the laser-entrance hole ** F.H. Séguin et al., Rev. Sci Instrum 74, 975 (23).
Yield per MeV Calibration of new WRFs and recalibration of WRFs used on the NIF have been conducted on the accelerator Energy (MeV) 3-line calibration of Zirconia WRF Deterioration during NIF campaign 2.E+8 1.6E+8 1.2E+8 8.E+7 14.65MeV 1.96MeV 7.21MeV 11.5 11 4.E+7 1.E+ 1 2 Energy, MeV 1.5 Before NIF N91115 N9124 After NIF 5 mm Al 4 mm Al Incident D-He3 protons Zirconia wedge CR-39 Both Aluminum and Zirconia WRFs showed no significant deterioration
Diagnostic #3: The Magnetic Recoil Spectrometer (MRS)
An MRS is currently implemented on the NIF for measurements of the ICF-neutron spectrum MRS on the NIF target chamber MRS (77-324 ) Polyethylene shielding CR-39 Magnet Alignment system Graduate student Dan Casey and the NIF MRS Cross-section of the MRS for the NIF
The MRS on OMEGA and the NIF are using CR-39 for detecting recoil protons or deuterons Implosion CH-foil or CD-foil 1 cm 215 cm Back side Front side CR-39 6-3 MeV (p) 3-15 MeV (d) This spectrometer measures the absolute neutron spectrum (6-3 MeV) from which ρr, T i and Y n can be determined for a large range of implosions. ** J.A. Frenje et al., Rev. Sci. Instrum. 72, 854 (21). J.A. Frenje et al., Rev. Sci. Instrum. (28).
y [ m] Counts / Pixel The coincidence counting technique (CCT) for the MRS at OMEGA was developed and optimized using the accelerator Incident Neutron CR39 4 Aligned 4 15 Misaligned 2 m 15 Incident proton / deuteron R l 2 2 1 1 Intrinsic noise Coincidence -2-4 -2 R c -4-4 -2 2 4 x = x x front = x 1 - -x back x 2 [ m] 5 R c -4-2 2 4 x [ m] 5 1 st etch - track etch 3 rd etch track etch signal is revealed again 2 nd etch bulk etch up - to 2 m removed By applying the CCT, S/B is enhanced orders of magnitude* * D.T. Casey et al., to be submitted to Rev. Sci. Instrum. (28). ** J.A. Frenje et al., Rev. Sci. Instrum. 72, 2597 (22).
Counts/cm y [cm] DHe 3 protons were used to test the CCT and to show that it properly subtracts background with a 2um bulk etch Background y [cm] 4 Signal Region Background Background Signal Region 5.7-3.7 MeV p x [cm] 1,5-4 1 2 3 4 5-5 -3-2 -1 1.1 ± 1.7 counts/cm 2 5-1 -2-3 3 2 1 1 1 15 2 2 3 25 4 215 ± 19 counts/cm 2-4 1 2 3 4 5 x [cm] 25 2 15 1 5-5 1, The background region is effectively zero, showing the CCT properly subtracts the background 5-5 -4-2 2 4 y[cm]
Some important references