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.