September 3-4, 2003/ARR1

ARIES-IFE

ARIES Project Meeting

Georgia Institute of Technology, Atlanta, Georgia

September 3-4, 2003

Summary of Issues, Results, Findings and R&D Guidance

Farrokh Najmabadi and A. René RaffrayUniversity of California, San Diego

September 3-4, 2003/ARR2

ARIES Integrated IFE Chamber Analysis and Assessment Research

Goals:

• Analyze & assess integrated and self-consistent IFE chamber concepts

• Understand trade-offs and identify design windows for promising concepts. The research was not aimed at developing a point design.

Approach:

• Six classes of target were identified. Advanced target designs from NRL (laser-driven direct drive) and LLNL (heavy-ion-driven indirect-drive) were used as references.

• To make progress, we divided the activity based on three classes of chambers:

- Dry wall chambers;

- Solid wall chambers protected with a “sacrificial zone” (e.g. liquid films);

- Thick liquid walls.

• We researched these classes of chambers in series with the entire team focusing on each concept.

• ARIES core team + contribution from a number of other players in the field.

September 3-4, 2003/ARR3

Example Results from ARIES-IFE Effort on Solid Wall Chambers

• Evolution of parametric

design window for carbon armor in a 6.5 m radius chamber for the 154 MJ direct drive target- Armor survival

(including time of flight effect)

- Laser breakdown constraint- Target survival

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–

–

–

0

500

1000

1500

2000

2500

3000

3500

0 100 200 300

Xe Pressure (mTorr )

Armor

Sublimation

Constraint

Laser

Target

September 3-4, 2003/ARR4

Example Results from ARIES-IFE Effort on Thin Liquid Wall Chambers

• Vapor and aerosol mass histories for a 6.5 m chamber with a flibe wetted wall exposed to the photon threat spectrum of the 400 MJ indirect-drive target- Potentially major effect on

choice of mode of transport and focusing of heavy ion driver based on pre-shot chamber gas density

- Neutralized ballistic transport:

<1 mtorr - Channel transport: <1 torr. - Self-pinched transport:

< 100 mtorr.

- Need better understanding of aerosol behavior including

coagulation at wall

0

1

2

3

4

5

6

10 100 10

3

10

4

10

5

tot_mass_data

Flibe Vapor Mass

Flibe Aerosol Mass

Mass in Chamber (kg)

Time (µs)

20 mtorr

100 mtorr

500 mtorr

200 mtorr

800 mtorr

September 3-4, 2003/ARR5

ARIES-IFE Effort on Thick Liquid Wall Chambers

• Indirect-drive target

- material choice

- constraints on chamber conditions

• Heavy-ion beam

- study of transport modes

- requirements on chamber conditions

• Liquid wall ablation mechanisms

- evaporation, explosive boiling

- spalling

• Chamber dynamics

- aerosol formation and behavior

- condensation and chamber clearing

• Liquid jet reformation and droplet formation

• Shielding of driver components

- final focus magnet

• Choice of chamber structural materials

Major Processes and Areas of Study

September 3-4, 2003/ARR6

Indirect Drive Target

• Key Issues

- material choice

- constraints on chamber conditions

• Results and Findings

- single use better than recycling

- window of material choice exists

- in-chamber tracking not needed for gas densities < ~ 1g/cm3 in a 3 m chamber

• R&D Guidance

- final selection requires overall system study

• Documentation

- partly in wetted wall paper

- material choice to be included in overall thick liquid wall paper

September 3-4, 2003/ARR7

Heavy-Ion Beam Driver

• Key Issues

- mode of transport

- constraints on chamber conditions

• Results and Findings

- neutralized-ballistic transport is main approach but tight constraint on vacuum (1 mtorr)

- pinch transport are higher risk, higher payoff alternatives (channel: 100 mtorr, self-pinch: 1 torr) but need to improve transport efficiency

- not much flexibility in relaxing requirements on chamber conditions

• R&D Guidance

- need focused modeling & experimental studies of assisted-pinch and self-pinch transport for further evaluation and improvement

• Documentation

- assisted pinch transport paper already prepared?

- possible self-pinched paper to be added?

- material choice to be included in overall thick liquid wall paper

September 3-4, 2003/ARR8

Liquid Wall Ablation Mechanisms• Key Issues

- evaporation and explosive boiling

- shock-wave induced spalling

• Results and Findings

- >~100 m of ablated thickness due to explosive boiling in flibe at 0.5 m from center --> leads to large impulse and shock wave

- will shock wave be dampened as it traverses the thick liquid jet?

- for free liquid jet, fracture occurs at the back of the jet following rarefaction wave formation

- will spalled material be cleared as pocket reforms or will it reach region outside the pocket and possibly affect driver transmission?

- vapor cloud from photon energy deposition will absorb most of the debris ion energy reducing the total amount of evaporated liquid

• R&D Guidance

- need combination of experimental and modeling studies to better understand and evaluate mechanisms under IFE like conditions

- experiments in facilities reproducing IFE photon energy deposition and time scale such as in a laser facility

• Documentation

- full journal paper being prepared

- also briefly summarized in town meeting paper

September 3-4, 2003/ARR9

Chamber Dynamics

• Key Issues

- aerosol formation and behavior

- condensation and chamber clearing

• Results and Findings

- need to prevent debris accumulation in beam access region

- need condensation surfaces for droplets ablated from inner surface of the pocket and venting through jet array

• R&D Guidance

- aerosol behavior in out-of-pocket region needs to be better understood

- comprehensive model required including ablation source term, gas dynamics, condensation and aerosol formation and dynamics

- condensation dynamics for prototypical material and conditions needs to be studied experimentally

• Documentation

- as part of town meeting paper

September 3-4, 2003/ARR10

Liquid Jet Dynamics

• Key Issues

- liquid jet reformation

- droplets formation

• Results and Findings

- possible droplets formation from criss-crossing series of jet could lead to unacceptable aerosol densities affecting driver transmission

• R&D Guidance

- Combination of scaled experimental and modeling studies to better understand droplet formation and behavior in a chamber-like jet geometry

• Documentation

- partly in overall thick liquid wall paper

- fully described in separate paper?

September 3-4, 2003/ARR11

Shielding of Driver Components

• Key Issues

- final magnet shielding

• Results and Findings

- should liquid shield be replaced by solid shielding block?

• R&D Guidance

-

• Documentation

- as part of overall thick liquid wall paper

September 3-4, 2003/ARR12

Structural Material Assessment

• Key Issue

- Choice of structural material for thick liquid wall chamber of HYLIFE IFE power plant

• Results and Findings

- Initial choice of 304SS to alleviate need for advanced structural material development. However, this raises possible swelling, activation and He embrittlement concerns

- Swelling and activation issues could perhaps be alleviated by compliant design and drastically reducing Nb and Mo impurities

- He embrittlement issue and thermal creep limits would seriously impact the operating temperature window (<~550C) when utilized in conjunction with a flibe blanket

- Recommendation that other structural materials (in particular ODS FS) be considered for power plant application

• R&D Guidance

- R&D info on advanced structural material, including ODS FS

• Documentation

- already documented as a UCSD technical report

- part of overall thick liquid wall paper

September 3-4, 2003/ARR13

Suggested List of Papers for ARIES-IFE Study on Thick Liquid Wall

1. Overall thick liquid wall paper: “Title to be confirmed”

2. Chamber dynamics paper based on town meeting presentations and discussion: “Thick Liquid Wall Chamber Dynamics: Key Issues, Existing Models and Experiments, and Future R&D”

3. Paper on ablation mechanisms: “IFE Liquid Wall Response to the Prompt X-ray Energy Deposition:Investigation of Physical Processes and Assessment of Ablated Material”

4. Paper on liquid jet dynamics including droplet formation: (separate or as part of overall paper?)

5. Other paper(s)?

September 3-4, 2003/ARR14

“Thick Liquid Wall Chamber Dynamics: Key Issues, Existing Models and Experiments, and Future R&D”

R. Raffray, W. Meier, S. Abdel-Khalik, R. Bonazza, P. Calderoni, C. Debonnel, Z. Dragojlovic, L. El-Guebaly, D. Haynes, J. Latkowski, C. Olson, P. Peterson, S. Reyes, P. Sharpe, M. Tillack and M. Zaghloul

Outline (some sections already written)

• Introduction (~1 page)

2. TLW Chamber Concept and Operation (~2 pages)- General description of TLW concept - Example HYLIFE-II design with HI driver and ID target - Driver and target constraints

3. Chamber/Liquid Wall Dynamics (~5-7 pages)Describe mechanisms with illustrative analytical results (as needed)- Liquid wall response to threats and early chamber dynamics (to ~1 ms)- Chamber clearing mechanisms (to ~100 ms)

4. Existing Models (~5-7 pages)(capabilities to simulate mechanisms described above, example results and planned improvement) (~0.5-1 page per model)

5. Existing Experimental Facilities (~5-7 pages)(capabilities to simulate and measure mechanisms described above,

6. R&D Needs

7. Conclusions

September 3-4, 2003/ARR15

“IFE Liquid Wall Response to the Prompt X-ray Energy Deposition:Investigation of Physical Processes and Assessment of Ablated Material”

M. Zaghloul, R. Raffray, and the ARIES Team

Outline (paper being written)

1. Introduction2. X-ray Energy Deposition

- X-ray Spectra- Photon Energy Deposition in The Cavity and Wall- Cold Opacities of Candidate Materials- Profiles of the Percentage of Energy Deposition in the Cavity and Wall

3. Wall Response (Physical Processes and Material Removal Mechanisms)- Thermal Response and Phase Transitions

- Normal (Surface) Vaporization- Normal Boiling (Vaporization into HeterogeneousNuclei)- Phase Explosion (Explosive Boiling) and HomogeneousNucleation

- Mechanical Response and Ruptures- Fractures and Spall

4. Material Properties- Relevant Material Properties of Candidate Materials- Theoretical Spall Strength and EOS

5. Modelling Approaches- Volumetric vs. Kinetic- Justification for the Volumetric Approach

6. Scoping Results - Results for different ablated amounts

- Pb, flibe- Comparison with ABLATOR

7. Discussion and Conclusions