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Highlights of ARIES-IFE Study
Farrokh Najmabadi
VLT Conference Call
April 18, 2001
Electronic copy: http://aries.ucsd.edu/najmabadi/TALKS
ARIES Web Site: http://aries.ucsd.edu/ARIES
Analyze & assess integrated and self-consistent IFE chamber concepts
Understand trade-offs and identify design windows for promising concepts. The research is not aimed at developing a point design.
Identify existing data base and extrapolations needed for each promising concept. Identify high-leverage items for R&D:
• What data is missing? What are the shortcomings of present tools?
• For incomplete database, what is being assumed and why?
• For incomplete database, what is the acceptable range of data? Would it make a difference to zeroth order, i.e., does it make or break the concept?
• Start defining needed experiments and simulation tools.
ARIES Integrated IFE Chamber Analysis and Assessment Research -- Goals
ARIES-IFE Is a Multi-institutional Effort
Program ManagementF. Najmabadi
Les Waganer (Operations)
Mark Tillack (System Integration)
Program ManagementF. Najmabadi
Les Waganer (Operations)
Mark Tillack (System Integration)Advisory/Review
Committees
Advisory/Review
Committees
OFESOFESExecutive Committee
(Task Leaders)
Executive Committee
(Task Leaders)
Fusion
Labs
Fusion
Labs
• Target Fab. (GA, LANL*)
• Target Inj./Tracking (GA)
• Chamber Physics (UW, UCSD)
• Chamber Eng. (UCSD, UW)
• Parametric Systems Analysis (UCSD, BA, LLNL)
• Materials (ANL)
• Target Physics (NRL*, LLNL*, UW)
• Drivers* (NRL*, LLNL*, LBL*)
• Final Optics & Transport
(UCSD, LBL , PPPL, MIT, NRL*,LLNL*)
• Safety & Env. (INEEL, UW, LLNL)
• Tritium (ANL, LANL*)
• Neutronics, Shielding (UW, LLNL)
Tasks
* voluntary contributions
We Use a Structured Approach to Assess Driver/Chamber Combinations
To make progress, we divided the activity based on three classes of chambers:• Dry wall chambers;• Solid wall chambers protected with a “sacrificial zone” (such
as liquid films); • Thick liquid walls.
We plan to research these classes of chambers in series with the entire team focusing on each.
While the initial effort is focused on dry walls, some of the work is generic to all concepts (e.g., characterization of target yield, target injection and tracking, etc).
An Integrated Assessment Defines the R&D Needs
Characterization
of target yield
Characterization
of target yield
Target
Designs
Chamber
ConceptsCharacterization
of chamber response
Characterization
of chamber response
Chamber
environment
Chamber
environment
Final optics &
chamber propagation
Final optics &
chamber propagation
Chamber R&D:Data base
Critical issues
Chamber R&D:Data base
Critical issues
DriverDriver
Target fabrication,
injection, and tracking
Target fabrication,
injection, and tracking
Assess & Iterate
Status of ARIES-IFE Study
Six classes of target were identified. Advanced target designs from NRL (laser-driven direct drive) and LLNL (Heavy-ion-driven indirect-drive) are used as references.
Detailed output spectrum from these targets are calculated and used for analysis of other systems.
Analysis of design window for successful injection of direct and indirect drive targets in a gas-filled chamber (e.g., Xe) is completed.
Final focus and transport is under study:
• Grazing incident metal mirrors for lasers.
• Focusing magnets for heavy ions and beam transport in a “high-pressure” chamber.
Status of ARIES-IFE Study
Six combination of target spectrum and chamber concepts are under investigation:
Nearly Complete,
Documentation
Direct drive
target
Work started
in March 2001
Dry wallSolid wall with
sacrificial layerThick Liquid Wall
Indirect drive
target
Work started
in March 2001
* Probably will not be considered because of large number of penetrations needed
*
X-ray and Charged Particles SpectraNRL Direct-Drive Target
1. X-ray (2.14 MJ)
2. Debris ions (24.9 MJ)
3. Fast burn ions (18.1 MJ)(from J. Perkins, LLNL)
3
1
2
• 1992 Sombrero Study highlighted many advantages of dry wall chambers.
• General Atomic calculations indicated that direct-drive targets do not survive injection in Sombrero chamber.
A Year Ago, Feasibility of Dry Wall Chambers Was in Question
Target injection Design Window Naturally Leads to Certain Research Directions
Chamber-based solutions:Low wall temperature: Decoupling of first wall & blanket temperaturesLow gas pressure: More accurate calculation of wall loading & response
Advanced engineered materialAlternate wall protection Magnetic diversion of ions*
Target-based solutions: Sabot or wake shield, Frost coating* * Not considered in detail
Target injection window
(for 6-m Xe-filled chambers):
Pressure < 10-50 mTorr
Temperature < 700 C
Example Temperature History for Carbon Flat Wall Under Energy Deposition from NRL Direct-
Drive Spectra (Vacuum Chamber)• Coolant temperature = 500°C
• Chamber radius = 6.5 m
• Maximum temperature = 1530 °C
• Sublimation loss per year = 3x10-13 m (availability=0.85)
Coolant at 500°C3-mm thick Carbon Chamber Wall
EnergyFront
Evaporation heat flux B.C at incident wall
Convection B.C. at coolant wall:h= 10 kW/m2-K • Wall Survives!
Example Temperature History for Tungsten Flat Wall Under Energy Deposition from NRL Direct-
Drive Spectra (Vacuum Chamber)
• Coolant temperature = 500°C• Chamber radius = 6.5 m• Maximum temperature = 1438 °C
Coolant at 500°C3-mm thick W Chamber Wall
EnergyFront
Evaporation heat flux B.C at incident wall
Convection B.C. at coolant wall:h= 10 kW/m2-K
Key issue for tungsten is to avoid reaching the melting point = 3410°C
W compared to C:• Much shallower energy deposition from photons • Somewhat deeper energy deposition from ions
An Efficient Dry-laser IFE Blanket With Low Wall Temperature Is Possible IFE dry-wall blanket example: ARIES-AT blanket. First wall
coated with C armor and is cooled by He. Coupled to advanced Brayton Cycle
Power loadings based on NRL targets injected at 6 Hz.
30% of power is in the first wall.
Blanket(e.g.
ARIES-AT)
Sep.FW
Pb-17Lioutin
He
BlanketPb-17Li (70% of Thermal Power)
He
FW (30% of Thermal Power)
~50°CIHX
Example Case: For a TFW of ~100-150°C, the
average surface Twall at target injection can be lowered to ~600°C while maintaining a cycle efficiency of 50%
Initial Results from ARIES-IFE have Removed Major Feasibility Issues of Dry Wall Chambers
Research is now focused on Optimization And Attractiveness
Trade-off studies are continuing to fully characterize the design window. We are analyzing response of the chamber to Higher target yields Smaller chamber sizes Different chamber wall armor
Un-going activities in: Engineered Material, Effect of chamber environment on target trajectory Final optics Safety