fusion technology institute university of wisconsin - madison nrl ife concepts project 9/19/2000 1...
Post on 21-Dec-2015
216 views
TRANSCRIPT
9/19/2000
1
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Output Calculations for Laser Fusion Output Calculations for Laser Fusion TargetsTargets
ARIES MeetingARIES MeetingSeptember 18-20, 2000September 18-20, 2000Princeton UniversityPrinceton University
Robert R. Peterson and Donald A. HaynesUniversity of Wisconsin-Madison
9/19/2000
2
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Laser Propagation:Breakdown
Variables Considered For Choosing the Cavity Gas Environment in SOMBRERO
Gas Opacity:Stop target x-rays and wall radiant heat
Stopping of Target Ions
Gas Atom Species
Density of Gas Atoms
Variables Considered For Choosing the Cavity Gas Environment in SOMBRERO
Neutron Activation of Gas
Target Injection
9/19/2000
3
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Chamber Physics Critical Issues Involve Target Output, Gas Behavior and First Wall Response
Design,Fabrication,
Output Simulations,(Output Experiments)
Design,Fabrication,
Output Simulations,(Output Experiments)
Gas Opacities,Radiation Transport,
Rad-Hydro Simulations
Gas Opacities,Radiation Transport,
Rad-Hydro Simulations
Wall Properties,Neutron Damage,
Near-Vapor Behavior,Thermal Stresses
Wall Properties,Neutron Damage,
Near-Vapor Behavior,Thermal Stresses
X-rays,Ion Debris,Neutrons
Thermal Radiation,
Shock
Target Output Gas Behavior Wall Response
UW uses the BUCKY 1-D Radiation-Hydrodynamics Code to Simulate Target, Gas Behavior and Wall Response.
9/19/2000
4
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
BUCKY is a Flexible 1-D Lagrangian Radiation-
Hydrodynamics Code • 1-D Lagrangian MHD (spherical, cylindrical or slab).
• Thermal conduction with diffusion.
• Applied electrical current with magnetic field and pressure calculation.
• Radiation transport with multi-group flux-limited diffusion, method of short characteristics, and variable Eddington.
• Non-LTE CRE line transport.
• Opacities and equations of state from EOSOPA or SESAME.
• Equilibrium electrical conductivities
• Thermonuclear burn (DT,DD,DHe3) with in-flight reactions.
• Fusion product transport; time-dependent charged particle tracking, neutron energy deposition.
• Applied energy sources: time and energy dependent ions, electrons, x-rays and lasers.
• Moderate energy density physics: melting, vaporization, and thermal conduction in solids and liquids.
• Benchmarking: x-ray burn-through and shock experiments on Nova and Omega, x-ray vaporization, RHEPP melting and vaporization, PBFA-II K emission, …
• Platforms: UNIX, PC, MAC
9/19/2000
5
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Direct and Indirect Drive Targets Under Consideration Have Different Output
DT Vapor
DT Fuel
Foam + DT
1 CH + 300 Å Au
0.265g/cc
0.25 g/cc1.5 mm
1.69 mm
1.952 mm
DT Vapor
DT Fuel
Foam + DT
1 CH
0.265g/cc
0.25 g/cc1.22 mm
1.44 mm
1.62 mm
NRL Direct-drive LaserTargets May Contain High Z
Indirect-drive HIF and Z-pinchTargets Have High-Z Hohlraums
DT gas
DT iceBe98O2
BeO
He gas
Au
0
2 mm
6 mmX-1 TargetLLNL/LBNL HIF Target
9/19/2000
6
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Original SOMBRERO Study Operated Under Substantially Different Target Assumptions Than Are Currently Used
Tmin (K) T Allowed (K)
Target Reflect-ivity
Wall Emis-sivity
Flight Length (m)
Flight Time (ms)
Gas Density (Torr)
Output Spectra
Yield (MJ)
SOMBRERO (1991)
4 14 0
(no Au)
1.0 6.5 16.3 Xe .5 given 400
SOMBRERO (2000)
18 0.5 – 1.7
.99 .8 < 2 < 5 Xe - Kr
< 0.5 given 400
NRL Target 18 0.5 – 1.7
.2 .8 2 – 6.5 5 – 16.3
Xe ? Calc. 160
9/19/2000
7
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Target X-ray Spectrum
Direct-Drive Target Output is Dominated by Neutrons and Energetic Ablator Ions
Debris Ions 94 keV D - 5.81 MJ141 keV T - 8.72 MJ138 keV H - 9.24 MJ188 keV He - 4.49 MJ 1600 keV C - 55.24 MJTotal - 83.24 MJ per shot=15.68 J/cm2 on SOMBRERO Wall
X-Rays22.41 MJ per shot=4.22 J/cm2 on SOMBRERO Wall
Neutrons317 MJ per shot=59.7 J/cm2 on SOMBRERO Wall
SOMBRERO Target
DT gas
DT iceCH
Z Experiments in Progress (6/15-6/21)Explosion of a thin plastic foil with Z-pinch x-rays (to simulate the explosion of an ablator) and a measurement of ion energies
9/19/2000
8
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Bucky Target Implosion and Burn Calculations used to Study Target Output
•Bucky does not have zooming or detailed LPI, so laser deposition will not agree with codes that do.
•Laser deposition comes from Andy Schmitt’s calculation.
•Pulse shape is then adjusted to get best implosion.
•Sensitivity of output spectra and partitioning to target yield is studied by adding energy to core.
Time (ns)
AbsorbedLaserPower(TW)
0 10 2010-1
100
101
102
NRL-DD-2NRL-DD-14
9/19/2000
9
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Time (ns)
Position(mm)
0 0.5 1 1.5 21.9
1.925
1.95
1.975
2
2.025
2.05
2.075
2.1
NRL DD-3515 Au zones
Laser
Au
CH
DT-wetted Foam
Laser Quickly Burns though 300 Ǻ Au and 1 Plastic and Launches a Shock in DT-wetted Foam
9/19/2000
10
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Time (ns)
Position(cm)
0 10 20 300
0.1
0.2
0.3
0.4
0.5
NRL DD-43
Au
CH
DT-wetted foam
DT
With Laser Pulse NRL-DD-14, Target Implodes and Ignites at 27.3 ns, giving 115 MJ of Yield
•22% of DT ice is burned; NRL and LLNL get about 32 %.
•Very little DT in wetted foam is burned.
•BUCKY burn fraction would be improved with further tuning.
•Target expands at a few x 108 cm/s and radiates.
9/19/2000
11
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Radius (cm)
MassDensity(g/cm3)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.710-4
10-3
10-2
10-1
100
101
102
20 ns22 ns24 ns26 ns27 ns27.2 ns
NRL The rmally S moothe d Dire ct-Drive Las e r Targe t
NRL-DD-43 Time (ns)0 10 20
0
10
20
30
40
NRL-DD-43
115 MJ NRL Laser Target
Implosion Keeps In-Flight Aspect Ratio Less than 40; Convergence Ratio is About 9
9/19/2000
12
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Time (ns)
FusionPower(TW)
23 24 25 26 27 28 29 30
10-3
10-2
10-1
100
101
102
103
104
105
106
NRL-DD-43
X-ray Emission from 115 MJ NRL Laser Target
Radius (cm)0 0.1 0.2
100
101
102
103
104
105
106
NRL-DD-43
115 MJ NRL Laser Target
At Bang Time = 27.3 ns
Most of Burn is in Cryogenic DT Ice and Takes Place in < 50 ps
9/19/2000
13
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Ion Energy (eV)
NumberofIons
103 104 105 106 107 108 1091016
1017
1018
1019
1020 DTHCAuHe
NRL-DD-43
Ion Spectrum from 115 MJ NRL Laser Target
Ion Spectrum for UW Best Burn
Wetted Foam
Plastic
Au
DT Ice
DT Gas
SOMBRERO
•Ion Spectrum is calculated from the velocity of each zone in the final time step of the BUCKY.•The particle energy of each species in each zone is then calculated as mv2/2.•The numbers of ions of each species in each zone are plotted against ion energy.•The spectra from direct fusion product D, T, H, He3, and He4 are calculated by BUCKY but are not shown in the figure (their numbers are low).•Regions of origin are shown. •In chamber calculations, these ions are assumed to be launched over 10 ns from the center of the chamber.
9/19/2000
14
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Ion Energy (eV)
NumberofIons
103 104 105 106 107 108 1091016
1017
1018
1019
1020 DTHCAuHe
NRL-DD-49
Ion Spectrum from 160 MJ NRL Laser Target
Wetted Foam
Plastic
Au
DT Ice
DT Gas
Ion Spectrum for UW Adjusted Burn
SOMBRERO
•Adjusted Burn has 140 MJ of burn plus an extra 20 MJ in the core plasma.•Since 30% of the fusion yield leaves the target as non-neutronic, x-ray and ion spectra are equivalent to a 200 MJ yield.•SOMBRERO ion energies (one energy for each species) are shown for reference.•Naturally, ion energies are higher in adjusted burn case (i.e. Au is 50 % more energetic)•Extremely high energies of a few Au ions do not agree with LLNL calculations (molecular flow?).
9/19/2000
15
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Radius (cm)
FinalChargeState
10 20 30
5
10
15
20
NRL-DD-49
160 MJ NRL Laser Target
Gold Ions are at a Charge State Between 10 and 25; Other Ions are Full Stripped
•Charge State of debris ions is important to deposition in Chamber Gas.
•At launch time (end of target explosion simulation), charge state is taken from data tables in temperature and density.
•The tables are calculated by the EOSOPA code in a Saha LTE method.
•The free electrons are assumed to move with the ions (quasi-neutrality).
•The greatly expanded target remnants are probably in Coronal Equilibrium or not in equilibrium at all.
9/19/2000
16
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
X-ray Spectra from Targets is Changed by High Z Components
•X-ray spectra are converted to sums of 3 black-body spectra. •Time-dependant spectra are in Gaussian pulses with 1 ns half-widths and are used in chamber simulations.• Time-integrated fluences are shown for Best UW calculation, adjusted yield, and SOMBRERO.•The presence of Au in the NRL targets adds emission in spectral region above a few keV.•At higher yield the Au is more important.
Photon Energy (eV)101 102 103 104 105 10610-7
10-6
10-5
10-4
10-3
10-2
10-1
160 MJ115 MJSOMBRERO
NRL-DD-43NRL-DD-49
X-ray Spectrum from 115 MJ and 160 MJ NRL and SOMBRERO Laser Targets
9/19/2000
17
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
Time (ns)
X-rayPower(TW/cm2)
0 10 20 3010-1
100
101
102
103
NRL-DD-49
X-ray Emission from 160 MJ NRL Laser Target
Time (ns)
X-rayPower(TW/cm2)
0 10 20 3010-1
100
101
102
103
NRL-DD-43
X-ray Emission from 115 MJ NRL Laser Target
X-ray Power Emitted from Target is Mostly from Target Explosion in 1 ns Burst, but Laser History
is Apparent
UW Best Adjusted Yield
9/19/2000
18
Fusion Technology InstituteUniversity of Wisconsin - Madison NRL IFE Concepts Project
DD-43 DD-49
Laser Energy (MJ)1.6 1.6
Fusion Yield (MJ)115.7 139.7
Added Energy (MJ)0 20
X-Ray Yield (MJ)1.66 (8%) 2.33 (7.3%)
Debris Yield (MJ)19.0 (92%) 29.7 (92.7%)
Total Non-Neutronic Yield (MJ)20.66 32.0
X-ray and Ion Debris Yield Partitioning Not A strong Function of Total Yield