Transcript latkowski-xapper

XAPPER Progress
September 2003 – January 2004
Presented by: Jeff Latkowski
XAPPER Team: Ryan Abbott, Robert Schmitt, Arturo Rodriguez,
Steve Payne, Ron Pletcher, Susana Reyes, Joel Speth
HAPL Program Workshop
Atlanta, GA
February 6, 2004
Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
Synopsis
 The quest for a high-quality ellipsoidal condensing optic
 Sample damage:
– Aluminum matrix
– Tungsten matrix
– Single crystal vs. powder met. tungsten
 In-chamber CCD imaging of x-ray spot
 Modeling
 New chamber planned
 Summary of recent progress
 Future plans
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The XAPPER experiment is used
to study damage from x-ray exposures
 Source built by PLEX LLC:
– Provides x-rays from 80-150 eV
– Operation for ~107 pulses before
minor maintenance
– X-ray dose can be altered by
changing focus, voltage, gas
pressure or species
– Facility is flexible and dedicated
to the study of x-ray damage
Z-pinch
plasma
Ellipsoidal
condenser
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Sample plane
Obtaining adequate x-ray focusing
has been a major hurdle for XAPPER
4/2002
10/2002
 Initial contract with PLEX LLC included funds for production
of two ellipsoidal condensing optics: one for use with xenon
@ 80-130 eV and one for use with argon at 250-300 eV
 A subcontractor produced the xenon optic, but it had obvious
flaws and failed to meet specification
1/2003
 The second xenon optic had similar problems
2/2003
 An optic for use with argon was produced  has never been
tested
4/2003
 Funds for optics production were removed from the PLEX
contract
5/2003
 We opted to enlist the help of LLNL’s Material Science &
Technology Division (Troy Barbee) and Baker Consulting
10/2003
 First mandrel received, first optic produced with some success
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Good focusing optics have been produced—
December 2003 (Merry Christmas!)
Fluorescer
Bulk Aluminum
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Al mirror (100 nm on SiO2)
Powder met. tungsten
Using our first high-quality ellipsoidal
condenser, pure tungsten can be damaged
 Significant damage is observed
at a fluence of ~1 J/cm2
9000 pulses @
~1 J/cm2 (est.)
Unexposed
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Pure tungsten can be damaged, (Cont’d.)
 Sub-mm particles, w/ sponge-like
appearance fill many depressions
throughout the sample
 Initially thought these were debris;
chemical analysis shows that they
are actually tungsten oxide
 Additional characterization is
underway to understand the
generation of these particles
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Materials test matrix
 We have tested samples at different fluences and
for different numbers of pulses:
– Pulses: 1, 10, 102, 103, 104
– Fluences: ~1 J/cm2, 0.82 J/cm2, 0.66 J/cm2
0.7
We hope to understand
how the fluence &
number of pulses affect
the damage
Intensity (a.u.)
0.6
Isample 9kV
Isample 10kV
Isample 11kV
0.5
0.4
0.3
0.2
0.1
0.0
0.07
0.08
0.09
0.10
0.11
0.12
Energy (keV)
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0.13
0.14
0.15
Al test matrix
 As would be expected, more severe damage is observed at
higher fluences and after a greater number of shots
 Much of the unexposed surface can be seen surrounding the
obvious damage sites
2
~0.82 J/cm
1000 shots
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10,000 shots
Al test matrix, (Cont’d.)
 Damage observed for even a single shot
 Not clear why damage is found in spots that are
several times smaller than the x-ray spot size
Region shown
on next slide
~0.66 J/cm2
1 shot
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1000 shots
Al test matrix, (Cont’d.)
 Ridges within exposed section appear to be periodic but
unrelated to ridges seen in unexposed image
~0.66 J/cm2
Unexposed
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1000 shots
Al test matrix, (Cont’d.)
 We are removing a significant amount of material:
– ~0.8 mm diameter regions (roughly equal to the spot size in the
reversed configuration)
– ~1.5 nm/shot  nearly constant at all fluences
– Too early to draw conclusions; vapor shielding, etc. could be
dominant effect at such high fluences
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Tungsten test matrix: 10,000 shots
on powder met.
0.82 J/cm2
~1 J/cm2
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Single crystal vs. powder met. tungsten
exposed to fluence of ~1 J/cm2
Unexposed
Single crystal tungsten
Powder met. tungsten
15 min. @ 10 Hz
(9000 shots)
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Single crystal vs. powder met.
tungsten, (Cont’d.)
Unexposed
Single crystal tungsten
Powder met. tungsten
15 min. @ 10 Hz
(9000 shots)
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Materials test matrix findings
 Early conclusion: Even 0.66 J/cm2 is too much – all samples
damaged in relatively few pulses
 Will test same samples at even lower fluences to look for
damage thresholds
 Testing with high-quality samples that are well characterized
prior to irradiation will begin after testing at lower fluences
Note: Remember to correct for spectral effects!! Do not
compare this 0.66 J/cm2 directly to the 1 J/cm2 x-ray
output expected in the 400 MJ direct-drive target.
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In-chamber CCD experiments – concept
 We completed a series of experiments
using an in-chamber CCD camera:
– Produced a new top plate for chamber,
allowing camera to fit within vacuum
– Filtered fluence by ~108 
– Placed CCD at/near ellipsoid focus
– Measured x-ray beam profile & energy
 A permanent CCD system
will be implemented on the new
chamber (Summer 2004)
 Thanks to Jim Dunn (LLNL’s
PAT Directorate, V Division) for
assistance and equipment
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 
pts 2
In-chamber CCD Experiments – results
 Measurements confirm spot size calculations and damage observations:
– ~2 mm spot (FWHM) in the original configuration
– <1 mm spot in the reversed configuration
Processed Image
 Since we have plenty of fluence to spare, will work to defocus beam and
obtain a sizable flattop region
Reversed Configuration
30 shot average
0.94 mm FWHM
Processed Image
img
Original Configuration
10 shot average
1.92 mm FWHM

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Intentionally Displaced Optic
10 shot average
We have developed the RadHeat code to model
pulsed thermal transients in the first wall and optics
RadHeat is a 1-D heat transfer code for use with multi-material
walls irradiated by any number of photon and/or ion spectra
in pulsed environments:
– Appropriate energy
deposition and
time-of-flight physics
are handled
460
440
420
400
Temperature (K)
– Convective and radiative
cooling of both front and
back wall surfaces is
handled as well as ability
to impose any initial
temperature profile.
380
360
340
320
300
0
5
10
15
Time (s)
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20
25
We are designing a new chamber
for use on XAPPER
Extra access ports for
visibility and future use
New larger sample tray
Larger ports for turbo pumps
(and arms)
Large diameter main chamber
for multiple diagnostics
Breadboard for auxiliary
component location
New chamber will be
installed Summer 2004
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Recent XAPPER achievements
 Specified ellipsoidal condensing optic, had mandrels
fabricated, and produced four acceptable optics
 Measured x-ray output & spot size in two configurations
 Demonstrated adequate x-ray focusing
 Demonstrated x-ray damage to aluminum mirrors,
monolithic aluminum, and powder met. Tungsten
 Completed basic test matrix for pure aluminum
 Developed RadHeat code for multi-pulse material heating
analyses
 Brought spectrometer operational
 Developed basic in-situ laser surface diagnostic
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Future directions for XAPPER experiments
 Complete exposure campaigns for aluminum and tungsten:
– Characterize damage, including roughening, as function of x-ray fluence,
number of pulses, etc.
– Multiple varieties of each material (e.g., CVD, single crystal, etc.)
 Enhance diagnostic capabilities:
– Procure/install fast optical thermometer (from UCSD)
– In-situ laser surface diagnostic for real-time surface characterization
 Improve diagnostic and equipment access with new chamber:
– Ability to directly view samples being exposed
– Locating pins on plasma head and optical table within chamber
– Larger ports making equipment removal/installation easier
 Other materials of interest include fused silica, carbon composites, and
various steels
 We are very interested in initiating the study of synergistic effects (e.g.,
damage to materials exposed to x-rays and ions or x-rays and lasers)
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FY04 Tasks
 Complete exposure campaigns, culminating in 106 pulse
runs, for tungsten/ferritic steel armor and aluminum mirrors.
 Characterize material roughening as function of x-ray
fluence and number of pulses.
 Further develop and benchmark predictive capabilities for
exposure to x-rays, neutrons, and ions.
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Backup slides