IFE Materials Response: Long-term exposure to nitrogen and helium beams on RHEPP Tim Renk Beam Applications & Initiatives Department Tina Tanaka Fusion & Structural Technology Department Sandia National Laboratories High Average Power Laser Workshop Madison, WI September 24-25, 2003 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.
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IFE Materials Response:
Long-term exposure to nitrogen and
helium beams on RHEPP
Tim RenkBeam Applications & Initiatives Department
Tina TanakaFusion & Structural Technology Department
Sandia National Laboratories
High Average Power Laser WorkshopMadison, WI
September 24-25, 2003
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy under contract DE-AC04-94AL85000.
• Smoothed W and Mo samples, providedby Lance Snead, were exposed to 250MAP N pulses from ~ 1.5 to 6.1 J/cm2
• Sample temperature held to 580 < T <600C - above brittle-ductile transitiontemp for both Mo and W
• Roughening threshold for pure W appearsto be ~ 1.25 J/cm2 , same as previouslymeasured at RT by reflectometer. Similarscaling with fluence for W25Re
• Mo exposed at 1.5 - 2.5 J/ cm2 roughensworse than heated W
• Both W and Mo appear to roughen belowmelt
Roughening threshold for 600C W predicted ~ 1.25 J/cm2;Looks like W/25Re has similar roughening, Mo worse
Pulsed Power Sciences, Sandia National Laboratories
TJR 4/08/2003
0
0.2
0.4
0.6
0.8
1
0 0.8 1.6 2.4 3.2 4 4.8 5.6 6.4
Ra W (exposed)
Ra Mo (exposed)
Ra W25Re (exposed)
Carbon Beam Fluence (J/cm2)
(mic
ron
s)
Melting fluence:Mo: 2.2 J/ cm2 W: 2.5 J/ cm2
• Smoothed W and Mo samples, providedby Lance Snead, were exposed to 250MAP N pulses from ~ 1.5 to 6.1 J/cm2
• Sample temperature held to 580 < T <600C - above brittle-ductile transitiontemp for both Mo and W
• Roughening threshold for pure W appearsto be ~ 1.25 J/cm2 , same as previouslymeasured at RT by reflectometer. Similarscaling with fluence for W25Re
• Mo exposed at 1.5 - 2.5 J/ cm2 roughensworse than heated W
• Both W and Mo appear to roughen belowmelt
Roughening threshold for 600C W predicted ~ 1.25 J/cm2;Looks like W/25Re has similar roughening, Mo worse
Pulsed Power Sciences, Sandia National Laboratories
TJR 4/08/2003
0
0.2
0.4
0.6
0.8
1
0 0.8 1.6 2.4 3.2 4 4.8 5.6 6.4
Ra W (exposed)
Ra Mo (exposed)
Ra W25Re (exposed)
Carbon Beam Fluence (J/cm2)
(mic
ron
s)
Melting fluence:Mo: 2.2 J/ cm2 W: 2.5 J/ cm2
Executive Summary
Pulsed Power Sciences, Sandia National Laboratories
TJR 9/20/2003
• Materials response to pulsed ion exposure is affected greatly bygrain structure. Roughening appears species-dependent for samedose, - He ions roughen worse than N.
• Roughening: is worst for PowderMet W, heated or not. Responsevaries significantly amongst metals tested, - Cu roughens hardlyat all, for example. Roughening evolves over hundreds ofpulses, and appears open-ended. Smaller-grain PowderMet Wmight help.
• Deep-lying cracking evident with W, W25Re, and Re. Depths arein the tens to hundreds of microns, and appear consistent withfatigue/stress cracking. Too deep for DekTak/WYCO to see.
• CFC Graphite (222-FMI) suffers material loss over 1000 pulses atthe 1.6 J/cm2 level, well below predicted ablation threshold.
• Foams seem to suffer material loss over 800 pulses, but hard totell exactly.
• C-C-W Velvet (Knowles) subjected to 200 pulses up to 7 J/cm2,survives amazingly well.
• Copper contamination an issue, but does not change majorconclusions
• 450x Helium Series: W, Mo Powder Met W
CVD WSingXtal, all 600C W25Re, Re unheated
• 1000x Nitrogen KS Series: W,Mo Powder Met 600C W25Re, Re CFC,Foams Ti-2,Al1100, Cu
• 600x Nitrogen series: W, Mo Powder Met 600C CFC, Foams higher fluence
Extended shot series taken since June 2003
Pulsed Power Sciences, Sandia National Laboratories
TJR 9/15/2003
Nitrogen injection into MAP produces3-component beam of mostly N++, N+
Pulsed Power Sciences, Sandia National Laboratories
TJR 6/6/2003
• Beam predominantly N++ and N+ aftersmall proton pulse at front
• Peak voltage = 850 kV Peak current density (total) ~145 A/cm2
• Total fluence = 7.9 J/cm2 - will ablatealmost all materials
• Total pulse width ~ 200 ns
• Ion range (TRIM):– N+ 0.9 µm, N++ 1.2 µm
• Oxygen, Neon beams similar
0
200
400
600
800
0 50 100 150 200 250 300
Voltage - ProtonsVoltage - N+2Voltage - N+1Proton current densityN+2 Current densityN+1 Current density
0
16
32
48
64
80
96
112
Time (ns)
Co
rrec
ted
Dio
de
Vo
ltag
e (k
V)
A/c
m2
Shot 31661
He beam (HE+1) pulsewidthis longer than N or C beam
Pulsed Power Sciences, Sandia National Laboratories
TJR 7/26/03
• He current lags voltage, leadingto debunching
• Current pulse width at 63 cm isalmost 0.5 µsec long
• Beam here was intentionallyattentuated
• He range in W (TRIM) ~ 0.9 µm
• Range similar to N beam because singly charged
0
0.5
1
1.5
2
200 300 400 500 600 700 800
Total Beam Current (FCups)Propagated He+1 current
Time (ns)
Curr
ent
(kA
)
0
100
200
300
400
500
600
50 100 150 200 250
Corrected Diode Voltage (kV)He+1 current (kA)
Time (ns)
(kV
)
(kA
)
5
2.5
Roughening of SS303, SS316LSvaries with ion beam species
Pulsed Power Sciences, Sandia National Laboratories
TJR 6/6/2003
• Polished SS303, 316LSexposed to 25 pulses eachof 3 beams at 2 J/cm2:
proton nitrogen argon
• Proton beam produces mostroughening (Ra and peak-valley)
• 303 roughens more in allcases then 316LS
• MAP N and MAP Ar producesimilar roughening, Arsmaller peak-valley
consistent with single-shot reflectometerroughening threshold
• Powder Met Mo (one point at 2.5J/cm2 ): roughness stays near unexposedvalue
• Above threshold, roughening is a severefunction of fluence. Maximum Ra exceeds22 µm, with P-V height above 70 µm
400 shot Map N shots on Tungsten (Room Temperature):Roughening only above threshold
Pulsed Power Sciences, Sandia National Laboratories
TJR 8/8/03
1
10
100
0 0.5 1 1.5 2 2.5 3 3.5 4
Ra W Ra W untreatRa Mo
Fluence (J.cm2)
Ra (
mic
ron
s)
• Smoothed PowderMetW, CVDW, andsingle XtalW, provided by Lance Snead,were exposed to 450 MAP He pulses ~ 1.0to 1.3 J/cm2. Heated to 600C, heated 3Xincluding heater failure
• W/25Re and Re samples also treated, from1.3 to 2.5 J/cm2. Samples at RT
• PwderMetW Roughening is significantlyworse than CVD or Single Crystal W.Latter are similar to powderMet W/25Reand Re. None are roughening appreciablycompared to untreated.
• Surface morphology for SingXtal and CVDW different from PowderMetW.
He Beam exposure, 450 shots;Powder Met W has worst roughening, even when heated
Pulsed Power Sciences, Sandia National Laboratories
Pulsed Power Sciences, Sandia National Laboratories
TJR 9/20/2003
W Untreated W Treated at 1.6 J/cm2 600 shots W Treated at 3.0 J/cm2 600shots
Mo Untreated Mo Treated at 1.6 J/cm2 600 shots Mo Treated at 3.0 J/cm2 600 shots
All images 50X magnification
Re and Nb Foam SEM images as function of fluence
Pulsed Power Sciences, Sandia National Laboratories
TJR 9/20/2003
Re Untreated Re Treated at 1.6 J/cm2 600 shots W Treated at 3.0 J/cm2 600 shots
Nb Untreated Nb Treated at 1.6 J/cm2 600 shots Nb Treated at 3.0 J/cm2 600 shots
All images 50x magnification
• Mechanically polished pyrolitic graphite(PG), Poco, and 4D carbon compositeweave exposed to 75 pulses/225 pulsesof 70% C /30% H beam at doses of 1.9to 5 J/cm2
• PG ablation threshold ~ 4 J/cm2• Poco ablation threshold ~ 3 J/cm2• Above threshold, rapid increase in
ablated material per pulse with dose.Data scatter reflects uncertainty in dose
• Composite matrix ablates more thanPG/Poco, fibers comparable (samplerough)
Response of graphite to mixed H - C beamqualitatively confirms BUCKY predictions
Pulsed Power Sciences, Sandia National Laboratories