Transcript ppt

XAPPER Progress: Summer 2004
Are we having fun yet?
New postdoc?
Presented by: Jeff Latkowski
XAPPER Team: Ryan Abbott, Robert Schmitt, and Brad Bell
XAPPER
HAPL Program Workshop
Princeton Plasma Physics Laboratory
October 27-28, 2004
Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under
Contract W-7405-Eng-48.
Overview
 Finally, a decent fluence measurement!
 RadHeat update
 New tungsten exposures
 Upcoming improvements
JFL—10/28/04
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
Sample
plane
Condensing
optic
Plasma
pinch
JFL—10/28/04
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
Zr filter (~108
attenuation)
1. Position CCD (along with its Zr filter) such that
chip is at sample plane. Take background and
actual images with XAPPER at ~0.3 Hz
Condensing
optic
Plasma
pinch
JFL—10/28/04
CCD
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
Zr filter (~108
attenuation)
1. Position CCD (along with its Zr filter) such that
chip is at sampleProcessed
plane. Take
Imagebackground and
actual images with XAPPER at ~0.3 Hz
Condensing
optic
Plasma
pinch
JFL—10/28/04
CCD
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
calorimeter
2. Position vacuum calorimeter at sample plane.
Operate XAPPER at 10 Hz and obtain steady-state
x-ray power. Determine x-ray energy per shot.
Condensing
optic
Plasma
pinch
JFL—10/28/04
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
calorimeter
2. Position vacuum calorimeter at sample plane.
Operate XAPPER at 10 Hz and obtain steady-state
x-ray power. Determine x-ray energy per shot.
Condensing
optic
Plasma
pinch
JFL—10/28/04
Finally, we have a decent
measurement of the x-ray fluence
 Fluence measurement and sample
exposures are made via a 3-step process:
3. Subtract background from x-ray spot profile.
Determine energy per count from calorimeter
result and total (bg-corrected) counts. Combine to
obtain peak x-ray fluence.
- If satisfied, rotate sample into focused beam
and shoot it.
Sample
Condensing
optic
- If not, adjust condensing optic, gas pressure,
discharge voltage, filtering, etc. to obtain
desired fluence.
Plasma
pinch
JFL—10/28/04
We observe acceptable shot-to-shot variations
 1-sigma variability over
300 shots:
– (x,y) position: ~6 mm
– intensity: <5%
– spot size: 4.5%
1 mm
JFL—10/28/04
Based on newly demonstrated fluence measurements,
we estimate earlier exposures were at a significantly higher
x-ray fluence than originally thought
90
80
Originally reported as
~0.7 J/cm2, we now
estimate these results
were for 1 J/cm2.
RMS roughness (nm)
70
60
50
40
30
20
Single crystal
Powder met.
10
0
0
5000
10000
15000
20000
# of pulses
JFL—10/28/04
25000
30000
We previously reported significant
differences between our RadHeat
results and those reported by Raffray
 We had not normalized the Perkins’ spectrum to give the correct integral
energy for each specie
 Rene makes minor adjustments to the tungsten properties:
– k = 70 W/m-K for T>3500 C
– cp = 200 J/kg-K for T>3000 C
 These changes account for most of the discrepancy
 We still have a difference of 200 C; the problem has been identified and a
work-around is in progress
JFL—10/28/04
Normalizing the spectra
brings our results into agreement
7.E+10
Rene's debris ions
Rene's burn ions
Ryan's debris ions
Ryan's burn ions
6.E+10
4.E+10
3.E+10
2.E+10
1.E+10
0.E+00
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
6.E+10
Depth (m)
5.E+10
Assumptions:
154 MJ target,
6.5 m radius
no chamber gas
Heating (J/m3)
Heating (J/m3)
5.E+10
4.E+10
Rene's debris ions
3.E+10
2.E+10
Rene's burn ions
Ryan's debris ions
Ryan's burn ions
1.E+10
0.E+00
1.E-10
JFL—10/28/04
1.E-09
1.E-08
1.E-07
Depth (m)
1.E-06
1.E-05
1.E-04
Adjusting the properties reduces
the peak surface temperature
3500
All ions
Burn ions
Debris ions
All ions -- new props
Temperature (K)
3000
2500
2000
1500
1000
Assumptions:
154 MJ target,
6.5 m radius
no chamber gas
JFL—10/28/04
500
1.E-07
1.E-06
1.E-05
Time (seconds)
1.E-04
1.E-03
We took shipment of a new white-light
interferometer (WLI) from Veeco




JFL—10/28/04
10, 50 objectives
0.5, 2 field-of-view optics
Automated x-y-z stage
Automated stitching
Tungsten exposures have been completed
at x-ray fluences of 0.5 and 0.7 J/cm2
 Each sample was hit in three different locations for
103, 104, and 105 pulses at 10 Hz
105 pulse damage sites
Single crystal
tungsten
JFL—10/28/04
Powder met.
tungsten
Pre-irradiation scans show that
the single crystal is very smooth
Ra = 7.7 ± 1.7 nm
JFL—10/28/04
The powder met tungsten is a bit rougher
Ra = 16 ± 1.8 nm
JFL—10/28/04
The single crystal tungsten is unchanged
or even slightly smoothed by the irradiation
Ra = 6.55 nm
25
105 pulses
@ 0.7 J/cm2
Ra = 5.58 nm
100
Unexposed
JFL—10/28/04
The single crystal tungsten is unchanged
or even slightly smoothed by the irradiation
9
Fluence = 0.7 J/cm2
RMS roughness (nm)
8
7
6
5
4
3
2
Single crystal
1
0
1
10
100
1000
# of pulses
JFL—10/28/04
10000
100000
Powder met. tungsten irradiated at
0.7 J/cm2 shows little, if any, roughening
Unexposed
Ra = 16 nm
100k pulses
Ra = 18 nm
1k pulses
Ra = 24 nm
100k pulses
Ra = 22 nm
JFL—10/28/04
Powder met. tungsten irradiated at
0.5 J/cm2 shows little, if any, roughening
Unexposed
Ra = 17 nm
100k pulses
Ra = 19 nm
JFL—10/28/04
We have installed a motor-controlled
manipulation system for the ellipsoidal optic
 3-axis LabView controlled
 Should be able to drive optic back to
desired location
 Could generate a “library” of beam
profiles and fluences (e.g., drive optic
to this position for 1 J/cm2 beam)
 Could use as an automated parameter
space search for a desired beam size
or fluence
JFL—10/28/04
We have irradiated one of Mark Tillack’s
mirrors with 3 MeV alphas
 CW exposure at grazing incidence (78º) and room
temperature; fluence of ~3 x 1017 a/cm2 
equivalent to 4.4 days for IFE optic @ 30 m / 85º
(1.1 days for optic @ 15 m)
 Observe bubble formation and significant drop in
(normal incidence) reflectivity:
– 87%  23% at 248 nm
– 93%  45% at 351 nm
– 98%  76% at 532 nm
 Magnetic deflection appears necessary:
– 0.1 T (at the center of the Helmholtz coil pair) is adequate
for optic @ 30 m
– 0.33 T needed for optic @ 15 m  able to stay with normal
magnets?
JFL—10/28/04
Upcoming improvements...
 Although we are reasonably happy with our fluence measurements, we very
much want to measure the surface temperature history  eagerly awaiting
the UCSD fast optical thermometer
 Sample heater has been problematic:
– Controller failures
– Testing in off-line system and expect move to XAPPER chamber in ~2 months
 Additional tungsten roughening studies:
– Utilize sample heater  start sample at 500ºC
– Measure temperature history and adjust fluence to match peak temperature
predictions for IFE armor
– Expose additional single crystal and powder met. tungsten samples to various
fluences and numbers of pulses from 1 to 105
 Additional foam exposures  how to characterize?
JFL—10/28/04