ion beam compression in space and time for hedp...
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The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 1
Ion Beam Compression in Space andTime for HEDP Applications*
A. W. Molvik, P. K. Roy, S. S. Yu, S. Eylon, E. Henestroza, F. M.Bieniosek, J. Coleman, B. G. Logan, W. L. Waldron, J. J. Barnard,
A. B. Sefkow, E. P. Gilson, P. C. Efthimion, R.C. Davidson, A.Friedman, W. M. Sharp, P. A. Seidl, D. R. Welch**, et al.
Presented on behalf of the
Heavy Ion Fusion Science - Virtual National LaboratoryLBNL, LLNL and PPPL
Innovative Confinement Concepts Workshop 2006
February 13-16, 2006, Austin, Texas*Research supported by the U. S. Department of Energy
** Mission Research CorporationUCRL-PRES-219387
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 2
The HIFS-VNL concentrates on the beam science commonto both High Energy Density Physics (HEDP) and fusion
We address a top-level scientific question central to bothHEDP and fusion:
How can heavy ion beams be compressed to the
high intensities required for creating high energy
density matter and fusion?
Principal science thrust areas & Outline of this talk:
- High brightness beam transport (my area)
- Focusing onto targets
- Longitudinal beam compression This talk
- Advanced theory and simulation tools
- Beam-target interaction (growing effort)
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 3
Significant progress towards HEDP and Fusion!
409220120
3-D simulation of electron cloud affecting ion beam vx vs x
409220222-409220257409220100 - 409220138
Measured vx vs x.
Slit x
vx
x
vx
Unique world class capabilityin electron cloud physics –flooding with electrons yields:
Beam phase space distortion
Electron drift oscillations
IBET – Ion Beam Electron Trap:• Ion beam potential (+2 kV) provides
radial confinement• Negatively biased rings at both
ends provide axial confinement• Here, downstream ring off – floods
with elec. from end wall
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 4
Significant progress towards HEDP and Fusion!
Unique ion pulse compression inplasma: From concept to simulation to50X compression data in 12 months
Unique neutralized final focus:Success from embracing,rather than avoiding plasmas
FWHM: 2.71 cm
Non-neutralized
FWHM: 2.14 mm
Neutralized
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 5
Developed new approach to ion-driven HEDP with muchshorter ion pulses (< few ns versus a few µs)
Maximum dE/dx and uniform heatingat Bragg peak require short (< few ns)pulses to minimize hydro motion.[L. R. Grisham, PoP, (2004)].Te > 10 eV @ 20J, 20 MeV(Future US accelerator for HEDP)
x
Ion energy loss rate in targets dE/dx
3 µm
3 mm
GSI: 40 GeV heavy Ions thicktargets Te ~ 1 eV per kJ
Aluminum
Dense, strongly coupled plasmas 10-2 to10-1 below solid density are potentiallyproductive areas to test EOS models(Numbers are % disagreement in EOSmodels where there is little or no data)
(Courtesy of Dick Lee, LLNL)
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 6
•Velocity chirp amplifies beam power analogous to frequency chirp in CPA lasers.
•Solenoids and/or adiabatic plasma lens (Z-pinch) can focus compressed bunches inplasma.
•Instabilities may be controlled with np>>nb, and Bz field [ Welch, Rose (MRC);Kaganovich (PPPL)].
LSP-PIC simulations demonstrate the possibility ofdramatically larger compression and focusing ofcharge neutralized ion beams inside a plasma column
Snapshots of a beam ionbunch at different timesshown superimposed
cm
cm
Ramped 220-390 keV K+ ionbeam injected into a 1.4-m -long plasma column:
•Axial compression 120 X.
•Radial compression to 1/efocal spot radius < 1 mm.
•Beam intensity on targetincreases by 50,000 X.
Existing 3.9T solenoid focuses beam
Backgroundplasma @ 10xbeam density(not shown)
Initialbunch length
(Welch et al., 2004)
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 7
Neutralized Transport Experiment (NTX)
FWHM: 2.71 cm
Non-neutralized
FWHM: 2.14 mm
Neutralized
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2 2.5 3 3.5
FL
UE
NC
E (
a.u
.)
R(mm)
MEVVA ONLY
Zero Space-charge
MEVVA and RF
Measurement
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2 2.5 3 3.5F
LU
EN
CE
(a
.u.)
R(mm)
MEVVA ONLY
100% neutralized
MEVVA and RF
Theory
MEVVA source(Plasma plug)
RF source(Target-region plasma)
300 keVK+ ions@ 25 mA
Nor
mal
ized
flu
ence
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 8
Measurements on the Neutralized Transport Experiment(NTX) demonstrate achievement of smaller transversespot size using target-region plasma
Neither plasma plug nortarget-region plasma.
Plasma plug. Plasma plug and target-region plasma.
P. K. Roy, et al., PoP 11, 2890 (2004).
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 9
Neutralized drift compression experiment (NDCX)- 300 keV K+ ions @ 25 mA
Tiltcore waveform
Beam current diagnostic
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 10
50 Fold Beam Compression achieved in neutralizeddrift compression experiment
LSP simulation
Corroborating data from Faraday cup
Optical data
Phototube Inte
nsity
(au
)
Time (ns)
Compression Ratio from Files 040505120632 and 120439 plotted 4/5/2005
0
10
20
30
40
50
60
4.92 4.93 4.94 4.95 4.96 4.97 4.98 4.99 5.00 5.01 5.02
Time [microsec]
Co
mp
ressio
n R
ati
o
0 100
60
40
30
20
10
50
Com
pres
sion
rat
io
0 100Time (ns)
P. K. Roy, et al., PRL 95, 234801 (2005).
Scintillator - Photomultiplier
F. Bieniosek
A. SefkowD.Welch
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 11
The ρ - T regime accessible by beam-driven experiments is similarto the interiors of giant planets and low-mass stars
Accessibleregion usingIntense beams (this decade)
Region is part ofWarm DenseMatter (WDM)regime
WDM liesat crossroadsof: degenerate/classicaland stronglyCoupled/weakly coupled
Figure adapted from “Frontiers in HEDP: the X-Games of Contemporary Science:”
Terrestialplanet
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 12
HYDRA simulations confirm temperature uniformity of targets at 0.1and 0.01 times solid density of aluminum (20 MeV Ne+ ions @ 330 A)
t(ns)
0
0.7
2.0
1.2
1.00.1solidAl
0.01solid Al(at t=2 ns)
2.2
Δz = 48 µr =1 mm
Δz = 480 µ
Axis
of s
ymm
etry
The Heavy Ion Fusion Virtual National LaboratoryA. W. Molvik – ICC06 – 13
Conclusions
There have been many exciting scientific advances and discoveries during the past two years:
- Demonstration of compression and focusing of ultra-short ion pulses in
neutralizing plasma background.
- These enable unique contributions to High Energy Density Physics (HEDP).
- Contributions to cross-cutting areas of accelerator physics and technology,
e.g., electron cloud effects, diagnostics.
Heavy ion research is of fundamental importance to both HEDP in the near (and long) term and to fusion in the longer term.
Experiments heavily leverage existing equipment and are modest in cost.
Theory and modeling play a key role in guiding and interpreting experiments.