T.E. Cowan, Y. Sentoku, M. Bakeman, B. Chrisman*, E. d’Humieres, S. Gaillard, J. Rassuchine*
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Transcript of T.E. Cowan, Y. Sentoku, M. Bakeman, B. Chrisman*, E. d’Humieres, S. Gaillard, J. Rassuchine*
T.E. Cowan, Y. Sentoku,M. Bakeman, B. Chrisman*, E. d’Humieres, S. Gaillard, J. Rassuchine*
Department of PhysicsUniversity of Nevada, Reno
Fusion Science Center of Excellence for Fast Ignition and Extreme States of Matter
NTF Status, Cone Target Physics
Chicago O’Hare Hilton 28 February 2007
Fusion Science Center of Excellence for Fast Ignition and Extreme States of Matter
NTF Status, Cone Target Physics
Chicago O’Hare Hilton 28 February 2007
*partial graduate support from FSC
• Schedule shift due to budget continuing resolution (CR)
• Commissioning and laser characterization planned through FY07
• Insufficient support for outside “users” while under CR
• Minimal “start up” test experiments might be possible within limited UNR program (i.e., collaboration, not as user)
• Point of Contact: T.C., or Jeff Thompson, Acting Director
Leopard laser commissioning in progress
On the brighter side…. Good progress with nanofabricated cone-shaped laser targets….
Free Standing Au (10 m wall)
Free Standing Cu (10m wall)
x-ray
proton
x-ray
HED
Smoother (!) than prior cones
Inside sub-micron tip apex: conical, with vestige of Si etch planes. Closer to sharp-tip, Sentoku simulation
37.3 um
16.7 um 3.33 um
1.0 um 500 nm
March 2006 LANL-Trident, enhanced proton beam, Au “pizza” tops~2.5% conversion efficiency to protons, 1.5x max energy(M. Hegelich, K. Flippo)
June 2006 LLNL-Titan, proton acceleration(P. Patel, J. Rassuchine, S. Gaillard)
July 2006 LULI-100 TW, Au “pizza” tops, reduced mass, pre-pulse!(S. Gaillard, J. Rassuchine, M. Bakeman, J. Fuchs, M. Borghesi, O. Willi)
August 2006 LANL-Trident, systematics of Au “pizza” tops, alignment!(K. Flippo, S. Gaillard, J. Rassuchine, M. Bakeman, M. Hegelich)
December 2006 LULI-100 TW, 1, 2 comparison with Cu cones & funnelsx-ray emission from hot Cu – similar to 50 m reduced mass(S. Baton, M. Koenig, J. Rassuchine, R. Kodama)
summer/fall 2007 LBNL-L’OASIS (3 J, 30 fs); LULI; LANL; Leopard
Experiment summary of x-ray production and proton beam generation
50 / 30 / 90 m
25 / 5 / 80 m
Typical Reduced-Mass “Pizza” Target Parameters: Neck OD / Neck ID / Top Diameter
Enhanced laser-coupling efficiency, and some increase in proton energy observed at Trident (LANL, UNR, GSI)
Range of neck and top parameters explored
Alignment is crucial… a postieri determination of laser coupling to cone (central or offset) from proton pattern
PIC simulation of longitudinal E-field
(E. d’Humieres)
Offset: acceleration from cone sides,lower peak proton energy
Central: acceleration from pizza top;1.5x higher peak proton energy,better collimation, conversion eff.compared to flat foil
dN/dE = 1.5e11 [p/MeV] * exp(-E / 4.5 MeV)
N ~ 6.1011 protons, 0.49 J, Elaser = 19 J, ~ 2.5%
1 10 100
0.01
0.1
1
10
C4+ heated
(~10% H+)
F7+ heated
(no H+)
F7+ unheated
H+ unheated
La
ser-
Ion
Co
nv.
Eff
ic.
(%)
Laser Pulse Energy (J)
several-fold increase in laser-proton acceleration
efficiency !
HH++ unheated unheatedpizza-toppizza-top
Enhanced acceleration efficiency, despite no surface treatment….more to come?
Titan: 200 J/500 fs(10 m Au, flat)
Nov-Dec 2006 S. Baton, M. Koenig, D. Batani, R. Kodama, J. FuchsJ. Rassuchine, Y. Sentoku, T.E. Cowan, E. d’Humieres (UNR)
Cu cones – sharp, blunt, “funnel”, with Cu Ka imaging & spectroscopy
Concerns about plasma pre-fill on reproducibility 2 vs. 1 comparison at LULI-100 TW
Pro
be b
eam
interferometry
2D-K imaging(rear side)
2D-K imaging(transverse)
Visible imageGOI
HISAC
K spectroscopy
Transverse Cu Ka imaging: 1#119)
2
High contrast improves laser penetration to cone neck…
Defocused 50umDefocused 50um with New PHA
- Smaller transverse size of emission zone at 2 (further into neck)
- Laser absorption occurs approx. further 50 m upstream, for 1 (ASE/prepulse contrast ~ 10-7:1)
2w,PH: Shot #96: Cone #47 2w,PH: Shot #98: Cone #432w,PH: Shot #97: Cone #48
Dcrystal= 8mm ∆lambda =
[1.5408:1.5402] = 0.0006 A
Defocused 50um
1w: Shot #120: Cone #501w: Shot #119: Cone #49Defocused 50um
with New PHADefocused 50um
with New PHA
Dcrystal= 8mm ∆lambda =
[1.5407:1.54] = 0.0007 A
1w: Shot #121: Cone #31
New PHA
Dcrystal= 8mm ∆lambda =
[1.5407:1.54] = 0.0007 A
Rear-side (end-on) Cu Ka imaging:
Rear surface imaging consistent with transverse…
- Smaller transverse size of emission zone at 2 (further into neck)
2w,Shot #96: Cone #47Defocused 50um
1w,Shot #119: Cone #49
Defocused 50um with New PHA
Rearside Cu Kalpha Imager
0
50
100
150
200
250
0 20 40 60 80 100 120
Shot Number
FW
HM
(u
m)
Sharp Tip Cone Blunt Tip Cone Funnel Cone Multilayer (0.2)V(10)Cu(10)Al Reduced Mass Multilayer
1w 2w 1w
Target Type FWHM(1w) (um) FWHM(2w) (um) ΔFWHM
Sharp Cone 143.9/126 56.7 42-52%Blunt Cone 105.2/102/7 59.7 62-66%
Funnel Cone 95.5 50.1 69%Multilayer Disk 178.42 94.9 8.90%
0 100 200 300 400
0
1000000
2000000
3000000
4000000
Inte
grat
ed In
tens
ity (
a.u.
)
Distance (um)
1w Blunt Cone is 22-37% smaller than Sharp Cone
1w Funnel Cone is 32% and 8% smaller than Sharp and Blunt cone respectively
2w Funnel Cone is 11% and 19% smaller than Sharp and Blunt cone respectively
Funnel Cone is 87% smaller than 300um Disk at 1w and 90% at 2w
Defocused 50um
Defocused 30um up
7.4 7.6 7.8 8.0 8.2 8.40
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
Inte
nsity
(a.
u.)
Wavelength
Spectrometer Data Definition
Lower energy continuum
Kα1 and Kα2
Total hot spectrum
Hot Spectrum
Continuum background
X-ray spectroscopy: increased emission from “hot” ionized-Cu for high contrast (5th order)
7.6 7.8 8.0 8.2 8.4
0
500
1000
1500
2000
2500
3000
3500
Inte
nsi
ty (
a.u
.)
Wavelength
1w Au Cone+(20)Al(50)Cu(20)Al #123 1w Funnel Cone #120 1w Blunt Cone #49 1w Multilayer (.2)V(10)Cu(10)Al
Hot Cu (K pk-to-valley) observed for cones vs. flat at 1
7.6 7.8 8.0 8.2 8.40
500
1000
1500
2w Blunt Cone #98 2w Funnel cone #87 2w Funnel Cone #96 2w D=50um Reduced Mass (.2)V(20)Cu(5)Al #103 2w Au Cone+D=300um (.2)V(10)Cu(10)Al #74
Inte
nsi
ty (
a.u
.)
Wavelength
2: ionization above F-like. Comparable yield/heating to 50 m dia. reduced mass, despite huge mass
1w: Total Cold Cu Ka for cones ~ 1.5x higher yield than Multilayer
2w: Total Cold Cu Ka for cone~ 2-4x higher yield than Multilayer and Reduced Mass
Conical Crystal Spectrometer
0
20000
40000
60000
80000
100000
120000
140000
0 10 20 30 40 50 60 70 80 90 100 110 120
Shot Number
To
tal
Inte
gra
ted
Ka
lph
a1
an
d
Ka
lph
a2
(a
.u.)
Sharp Tip Cones Blunt Tip Cones Funnel Cones Multilayer Targets Reduced Mass Targets
1w 2w 1w
“Cold” K yield (Ne-like to neutral)
Conical Crystal Spectrometer
0
5000
10000
15000
20000
25000
0 10 20 30 40 50 60 70 80 90 100 110 120
Shot Number
Ho
t S
pe
ctu
m (
a.u
.)
Sharp Tip Cones Blunt Tip Cones Funnel Cones MultiLayer Flat Reduced Mass Targets
1w 2w 1w
“Hot” Cu x-ray yield (Li-like to F-like)
- Nanofabrication techniques are promising.….
- Preplasma filling (laser contrast) appears to be very important….
- Enhanced proton acceleration observed (confined hot electron sheath)
- X-ray emisison from hot matter observed (similar to reduced mass foils)
- Interesting alternative/complement to reduced mass targets:- hot electron concentration- maintains sheath quality for acceleration- more mass for x-ray production- mass produced on wafer- relaxed handling (at cost of more stringent contrast & pointing)- complex geometries possible
2006 progress in sharp-tip cone target physics: