Control System for Cryogenic THD/DT Layering at the ... controlled cryogenic environment NIF-0911-22972.ppt Fedorov - ICALEPCS Conference France, October 10-14, 2011 9 ... • Data-driven

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

LLNL-PRES-501052

Control System for Cryogenic THD/DT Layering at the National Ignition Facility

13th International Conference on Accelerator and Large Experimental Physics Control SystemsOctober 13, 2011M. Fedorov, C.J. Blubaugh, O.D. Edwards, M.Y. Mauvais, R.J. Sanchez, B.A. WilsonNational Ignition Facility, Control and Information Systems

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Cryogenic Target System

Cryogenic Target System

Robust formation of high quality DT ice layers is a challenging task which demands a precise and flexible control system.

NIF-0911-22972.pptNIF-0911-22972.ppt Fedorov - ICALEPCS Conference France, October 10-14, 2011Fedorov - ICALEPCS Conference France, October 10-14, 2011

Ignition experiments at NIF require cryogenic targets with uniform

layers of DT fuel

The Deuterium-Tritium (DT) ice layer is an integral component of the ignition target design

Fedorov - ICALEPCS Conference France, October 10-14, 2011 3NIF-0911-22972.ppt

DT Ice Layer 68±1 µm

2mm Ø

Temperature 18.3K

The high quality DT ice layers are spherical and smooth, meeting the specification metrics

Non-Spherical Shape Local Defects

NIF-0911-22972.ppt 4Fedorov - ICALEPCS Conference France, October 10-14, 2011

Spherical layers are formed in a uniform thermal environment using Beta-Layering

DT sublimation

DT condensation

Warmer region

ΔT = Qh2 /2κ

Self-heating due to beta decay results in DT sublimation from thicker, warmer regions and condensation, ice layer growth in thinner areas

Beta-Layering helps forming a spherical layer in isothermal capsule. Not efficient in preventing local defects, "grooves".


Local defects are eliminated by executing the Single Seed Crystal Growth layering protocol


Both Beta-Layering and Single Seed Crystal Growth require precise cryogenic temperature controls

NIF Target Positioner

ITIC Cryostat

Target


Cryotarpos


CryoTARPOS

Ignition Target Insertion Cryostat (ITIC) provides a controlled cryogenic environment


Target before the shot View of target from laser entrance hole

“Cryo THD ice layer” at ~19 deg K

68μm

2mm

2.3 cm

1 cm

T5H5

T1

T11

T13

H11

H1

T3T7 H7

H3

Target temperatures are controlled down to 1 mK precision at multiple points

• High precision PID control

• Data-driven software engine

• Helium tank thermal capacitor

• Thermal shielding and isolation


18.560

18.562

18.564

18.566

18.568

18.570

0 10 20 30 40 50 60 70Time (min.)

Tem

pera

ture

(k)

Temperature Stability

1 minute average

1 mk

Fuel ice characterized along three orthogonal directions using x-rays

Distribution of DT fuel is monitored and measured using a three-axis x-ray imaging system


Computer-enhanced, phase-contrast x-ray imaging reliably detects the ice layers inside of a Beryllium (Be) or a Plastic (CH) capsule

Cryogenic and imaging hardware is controlled by automatic, data-driven software engines

Capsule Wall

DT Ice Layer


A Layering Toolbox for MATLAB supports interactive development and analysis of evolving protocols

Image Analysis

Data Analysis

Development

Interactive ControlsMonitoring


Grooves Sphericity

A Layering Report determines target readiness for an ignition experiment


Report recommendation “all specs met, shoot”

0.00001

0.0001

0.001

0.01

0.1

1

Pow

er s

pect

ral d

ensi

ty (μ

m2 )

1 10 100Mode Number

Cryogenic Activity starts independently, then joins the NIF Shot Cycle

Setup Cooldown Fill Seed Layering Maintain !

8h

17h3h6h

NIF Ignition Shot

1h

Warmup3h

Cryogenic Activity


Final temperature adjustments and shroud opening are performed seconds prior to main laser shot

Start Quenching

Open Shroud

Shot


17.0

Tem

pera

ture

(k)

1

Time (s)

17.5

18.0

18.5

19.0

-50 -40 -30 -20 -10 0 10

Since 2010, the Cryogenic Target System supported 72 NIF experiments, including 18 with layered targets

• Integrated hardware-software system provides a robust and accurate platform for cryogenic target experiments

• Automatic data-driven process consistently executes complex layering protocols

• Flexible interactive environment simplifies evaluation of new target designs and supports layering research


Documents

Control System for Cryogenic THD/DT Layering at the ... controlled cryogenic environment NIF-0911-22972.ppt Fedorov - ICALEPCS Conference France, October 10-14, 2011 9 ... • Data-driven