the heavy ion fusion virtual national laboratory highly compressed ion beams for warm dense matter...

The Heavy Ion Fusion Virtual National Laboratory

Highly Compressed Ion Beams for Warm Dense Matter Science*

Alex Friedman1,2, John J. Barnard1,2, Richard J. Briggs7, Debra A. Callahan2, George J. Caporaso2, C. M. Celata1,3, Ronald C. Davidson1,4,

Andris Faltens1,3, Larry Grisham1,4, David P. Grote1,2, Enrique Henestroza1,3, Igor Kaganovich1,3, Edward P. Lee1,3, Richard W. Lee2, Matthaeus Leitner1,3,

B. Grant Logan1,3, Scott D. Nelson2, Craig Olson1,5, Gregg Penn3, Lou Reginato1,3, Tim Renk5, David Rose6, Andrew Sessler1,3,

John W. Staples1,3, Max Tabak2, Carsten Thoma6, William Waldron1,3, Dale R. Welch6, Jonathan Wurtele3, Simon S. Yu1,3

1. Heavy Ion Fusion Virtual National Laboratory2. Lawrence Livermore National Laboratory, University of California, Livermore CA3. Lawrence Berkeley National Laboratory, University of California, Berkeley CA4. Princeton Plasma Physics Laboratory, Princeton NJ5. Sandia National Laboratories, Albuquerque NM6. Voss Scientific, LLC, Albuquerque NM7. Science Applications International Corporation, Alamo CA

*Work performed under auspices of USDOE by U. of CA LLNL & LBNL, PPPL, and SNL, under Contract Nos. W-7405-Eng-48, DE-AC03-76SF00098, DE-AC02-76CH03073, and DE-AC04-94AL85000, and by ATK and SAIC.

Presentation No. BP1.0008147th Annual Meeting of the APS Division of Plasma Physics, Denver, Oct. 24-28, 2005


Outline

• High Energy Density Physics (HEDP); Warm Dense Matter regime

• Beam requirements

• Experiments & modeling– Neutralized focusing– Neutralized pulse compression

• Accelerator

• Plans


High Energy Density Physics is now a mission of the Heavy Ion Fusion VNL

• Long-term goal remains Inertial Fusion Energy (IFE)

• Emerging interest in HEDP near-term HIF effort focused on HEDP

• IFE is HEDP, but we now need to heat targets in the near term– HEDP is 1011 J/m3 ; p hydro time ~ 1 ns– Not yet accessible with our ion drivers; must develop capability

• “Warm Dense Matter” (WDM) regime of strongly-coupled few-eV plasmas at 10-2 to 10-1 of solid density is the first step– Interesting, and challenging, because these are neither

classical plasmas nor ordinary condensed matter

Ion-driven HEDP

J. J. Barnard, Poster LP1.80, 2:00 Wed.; see also PAC05 proceedings


The - T regime accessible by beam driven experiments is that of the interiors of gas planets and low-mass stars

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Accessibleregion usingbeams in nearterm

Region is part ofWarm Dense Matter (WDM) regime

WDM liesat crossroadsof degeneratevs. classicaland stronglycoupled vs. weakly coupled

Figure adapted from “Frontiers in HEDP: the X-Games of Contemporary Science:”

Terrestialplanet


R. More: Large uncertainties in WDM region arise in the two phase (liquid-vapor) region

Accurate results in two-phase regime essential for WDM

R. More has recently developed new high-quality EOS for Sn

Interesting behavior in the T~1.0 eV regime

EOS tools for this temperature and density range are just now being developed.

P (J/cm3)

T (eV) (g/cm3

Critical point unknown for many metals, such as Sn

R. Lee plot, showingcontoursof fractional pressure difference between two common EOS’s for Al

New theoretical EOS work meshes very well with the experimental capabilities we are creating


Ion beam heating offers unique opportunities for HEDP science

Advantages of Bragg-peak ion heating:

• Uniform heating of large volumes (few %) aids diagnosis• Volumetric energy deposition: no shocks, no x-ray or e- preheat• Time scales long enough for equilibrium conditions • Beam deposits ~75% of its energy; can measure beam changes• High repetition rate valuable for setup, diagnostic tuning

[ See L. R. Grisham, Phys. Plasmas 11, 5727 (2004). ]

z

50 mAl foam

10% solid

3 mm

dE/dX

GSI: 40 GeV U, Te ~ 1eV @ 1kJ long cylindrical targets

HIF-VNL: Bragg peak heating to maximize dE/dx & uniformity 24 MeV Na+, Te ~ few eV @ ~ 2.5 Jfoil targets, ~ 1 mm radius spot, ~ 1 ns pulse enabled by

using metallic foamto minimize hydro motion

Ion energy loss rate in

targets


Innovations and a new approach are required to rapidly heat a small volume

Beam Production

Accel-decel / load-and fire injector

Ion Transport via solenoids

Acceleration via one of:- RF- DTL - Single-gap diode- Ionization-Front Accelerator- Pulse-Line Ion Accelerator

Longitudinal Compression

Neutralized drift compression

Transverse Focusing

Strong solenoid,Plasma lens,Two-stage focus, or Plasma channel pinch

Workshop on Accelerator Driven High Energy Density Physics, LBNL, Oct. 26-9, 2004, brought together experts in targets, HEDP/WDM physics, accelerators:http://hifweb.lbl.gov/public/hedpworkshop/toc.html

Solenoid confines the slowed, high line-charge beam

Other approaches are possible

Beam requirements

http://hifweb.lbl.gov/public/hedpworkshop/tableofcontents.html



Beam requirements for 1 eV regime (NDCX-II)

At Injector Before Compression

At Final Focus (neutralized)

Energy (MeV) 1.0 ( = 0.01) 23.5 ( = 0.047) 23.5 ( = 0.047)

Pulse Duration (ns) 177 20 1

Pulse Length (m) 0.5 0.28 0.014

Dimensionless Perveance K 1.810-3 1.410-4 2.810-3

Momentum Spread p / p 210-3 710-4 0.015

• Na+ (A = 23), total charge = 0.1C (61011 ions)

• Normalized emittances: nx = 2.3 mm-mrad, nz = 33 mm-mrad

• Focus via 15 T solenoid; focal length ƒ = 70 cm

• Focal spot radius rspot = 1 mm

~

We are running a state-of-the-art hydro code, Hydra, to quantify beam req’ts

J. J. Barnard, Poster LP1.80, 2:00 Wednesday; also PAC05


GatedCamera

Neutralized Transport eXperiment (NTX) at LBNL was used to study neutralized focusing of high-perveance ion beams

Neutralized Focusing


Non-neutralized Plasma plug

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1400

0 2 4 6 8 10 12 14X(mm)

Non-neutralizedtransport

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1400

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Plasma Plug andVolume Plasma

FWHM=6.6 mm FWHM=2.2 mm FWHM=1.5 mm0

1

95%neutralized

6 mA Plasma density = 2 x 1011 /cm3

Reduction of spot size using plasma plug and volume plasma was measured

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Plasma Plug

Plasma plug &volume plasma


300 kV Marx GeneratorIon Source

FocusingQuadrupoles Diagnostics Diagnostics

Tilt Core Neutralized DriftCompression Section

Vacuum Tank

Neutralized Pulse

Compression

The Neutralized Drift Compression Experiment (NDCX-1a) uses an induction core to impart a velocity “tilt” to a section of the beam


Initial neutralized drift compression experiment (NDCX-1a) … 300 keV K+ ions @ 25 mA

Tilt-core waveform


~ 50x longitudinal compression of neutralized beam was measured via phototube & Faraday cup, and simulated

LSP simulation

Faraday cup data

Phototube data

Phototube

Time (ns)

Compression Ratio from Files 040505120632 and 120439 plotted 4/5/2005

0

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4.92 4.93 4.94 4.95 4.96 4.97 4.98 4.99 5.00 5.01 5.02

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Extended drift length (2-m) experiment demonstrates robust neutralized compression

• Greater sensitivity to neutralization

• Longitudinal beam temperature < 2 eV

• No evidence of two-stream degradation


• LSP has guided NDCX experiments • EDPIC has clarified how beam motion through plasma generates waves

Simulations help us understand beam flows in plasmas

Kaganovich PAC05

BeamB

Beam is injected with: 1.9-cm outer radius -22 mrad angle 0.05 mm-mrad emittance 0.21 eV Tparallel

Thoma PAC05, Sefkow PAC05


For HEDP studies, the accelerator, drift compression, and final focus must all work together

Na+

One concept: the beam …• enters in Brillouin flow with a 5-10% velocity tilt …• transitions to a Neutralized Drift Compression region …• is focused by a strong solenoid …• and by an assisted-pinch discharge channel, onto the target.

Issues:• Effectiveness of dipole trap at preventing plasma flow upstream• Transition from Brillouin flow to neutralized transport• Control of beam plasma instabilities and stripping in long plasma columns


Accelerator October workshop identified 5 approaches http://hifweb.lbl.gov/public/hedpworkshop/toc.html

RF Linac, w/ or w/o stacking ring

Staples, Sessler, Ostroumov, Chou, and Keller, PAC05

Ionization Front Accelerator

Olson, WS Proceedings

Drift-Tube Linac

Faltens, WS Proceedings

Pulse-Line Ion Accelerator (PLIA)

Single-gap diode

Olson, Ottinger, and Renk, WS Proceedings



1 eV target heating>0.1 C of Na+

24 MeV Bragg peak

1 eV target heating>0.1 C of Na+

24 MeV Bragg peak

Short PulseInjector

Short PulseInjector

SolenoidFocusing

SolenoidFocusing

PLIAAcceleration

PLIAAcceleration

NeutralizedCompression

NeutralizedCompression

FinalFocus

FinalFocus

A new accelerator concept (PLIA) can lead to a near-term HED facility (NDCX-II) with ten fold reduction in cost per MeV


PAC05: Briggs Henestroza WaldronCaporasoNelsonRoy

Compact transformer coupling (5:1 step-up)

Pulse Line Ion Accelerator (PLIA) is based on a distributed transmission line (helix)

Vs(t) from Pulse Forming Network

An NDCX-2 Accelerator Cell

Helical Winding in Epoxy

Solenoid Cryostat

Vacuum PumpingFirst low voltage bench test

(R.J. Briggs, et al. - LBNL patent, 2004)


z(m) z(m) z(m) z(m)z(m)

Longer beam is accelerated by “snowplow” (snapshots in lab frame)

V (kV)

Ex (kV)

z(m) z(m) z(m) z(m) z(m)

V (kV)

Ex / 10 (kV)

z(m) z(m) z(m) z(m) z(m)

PLIA can be operated in a short pulse (“surfing”) mode or a long pulse (“snowplow”) mode

Short beam “surfs” on traveling voltage pulse (snapshots in wave frame)


ParticlesEnergy(MeV)

Helix Voltage(MV)Current (A)

HELIX ENTRANCE

HELIX EXIT

Z (m) Z (m) Z (m)

Z (m) Z (m) Z (m)

WARP3d simulation of NDCX-1d clarifies beam dynamics in the helix under the influence of space charge


Initial Pulse-Line Ion Accelerator tests are underway

HV Cable

Primary Turn

BeamDirection

HelixWinding

Glass TubeGroundReturn

Outer OilVessel

SupportStructure


Helix #1 Input and Stepped-up Helix Voltage at 4" Intervals

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.0E+00 5.0E-08 1.0E-07 1.5E-07 2.0E-07 2.5E-07 3.0E-07 3.5E-07 4.0E-07 4.5E-07

Time [sec]

Signal [V]

Input end

€

υ ph =1

LC

Input

Output end

V(z) along the air-dielectric helix


High field solenoids

Helix accelerating structure

(in ‘snowplow’ mode)Matching solenoids

Source(accel/decel)

Beam species K+

Total charge 0.1Cnxnz=(1mm-mrad) x (8mm-mrad)

[ of NDCX-II design goal] €

⇒ Na+( )

€

1 10

We have designed a short pulse injector (NDCX-IC) which can serve as the front-end of NDCX-II


Decelerates theDecelerates thebeam headbeam head

Time ( s)

€

Negative pulse accelerates tailmore than head, giving tilt

Main snowplow: shaped so that tail of pulse arrives at end of helix as beam end arrives there. This gives the beam an overall “tilt” in longitudinal phase space

Voltage (MV)

Strong longitudinal space charge effects in the snowplow can be controlled by shaping the voltage waveform


€

€

€

€

€

€

3-D WARP calculations show how the design goals for the NDCX-II injector may be met

NDCX 1a,b,d experiments (next 2-3 years) can be done with existing equipment

Inter-changeable

HIF-VNL Plans

Near-term plan centers on one facility with inter-changeable parts, to be used for several experiments

quads

NDCX-1cLoad & Fire

Injector

NDCX-1dPulse-Line Ion Accelerator (Helix)

NDCX-1aNeutralized Drift

Compression

NDCX-1bSolenoid Transport

Inter-changeable


50-100x compression & solenoid transport(NDCX-1a,b) 2006-7

High- injector &PLIA w/ 0.1 C, 4 MeV(NDCX-1c,d) 2008-9

Integrated experiment w/ target heating to few eV

(NDCX-2) 2010-11

A sequence of steps leads to an instrumented user facility

Add chambers, targets, diagnostics

NDCX-1c + ~ $5M hardware > 0.1 C Na+ @24 MeV

Rep-rated (>10 Hz) system for studies of WDM at 1-10 eV (HEDP user facility) 2015-6

Related papers at this meeting

• MONDAY (THIS SESSION)– S. Eylon, “Development of Fast Diagnostics for High Intensity Ion Beams,” BP1.83– J. Coleman, “Low Voltage Beam Experiments on the PLIA,” BP1.84– F. Bieniosek, “Diagnostic Development for Heavy-Ion Based HEDP and HIF

Experiments,” BP1.89– E. Henestroza, “Numerical Simulations of a Pulse Line Ion Accelerator,” BP1.98– P. C. Efthimion, “Ferroelectric Plasma Source for Heavy Ion Beam Charge

Neutralization,” BP1.101– A. Sefkow, “A Fast Faraday Cup for Measuring Neutralized Drift Compression,”

BP1.103– E. A. Startsev, “Two-stream instability for a longitudinally-compressing charged particle

beam,” BP1.104• WEDNESDAY

– P. K. Roy, “Progress on neutralized drift compression experiment (NDCX-Ia) for high intensity ion beam,” KO1.15, Oral at ~12:18 PM

– B. G. Logan, “Potential for Accelerator-Driven Fast Ignition,” KZ1.2, Oral at ~10:10 AM– J. J. Barnard, “Simulations of particle beam heating of foils for studies of warm dense

matter,” LP1.80, Poster at 2:00 PM• FRIDAY

– E. Henestroza, “High Brightness Accelerator for Warm Dense Matter Studies,” UP1.16, Poster at 9:30 AM

– D. R. Welch, “Longitudinal compression of an ion beam in the NDCX experiment,” UO1.10, Oral at ~11:18 AM


Related papers in Proc. PAC05 (IEEE/APS Particle Accelerator Conference), Knoxville, May 2005: http://snsapp1.sns.ornl.gov/pac05/…

• A. Friedman, “Highly compressed ion beams for High Energy Density Science” …ROAB003/ROAB003.PDF• R. J. Briggs, “Helical Pulseline Structures for Ion Acceleration” …ROAB005/ROAB005.PDF

• E. Henestroza, “Extraction and Compression of High Line Charge Density Ion Beams” …FPAT028/FPAT028.PDF• W. Waldron, “High Voltage Operation of Helical Pulseline Structures for Ion Acceleration” …FPAT029/FPAT029.PDF• G. Caporaso, “Dispersion Analysis of the Pulseline Accelerator” …FPAT034/FPAT034.PDF• S. D. Nelson, “Electromagnetic Simulations of Helical Based Ion Acceleration Structures” …FPAT037/FPAT037.PDF

• P. Efthimion, “Ferroelectric plasma source for heavy ion beam charge neutralization” …TPAT036/TPAT036.PDF• A. Sefkow, “A fast faraday cup for the neutralized drift compression experiment”…TPAT068/TPAT068.PDF

• F. Bieniosek, “Optical Faraday Cup for Heavy Ion Beams”…RPAT022/RPAT022.PDF

• J. Staples, “RF-Based Accelerators for HEDP Research”…RPAP023/RPAP023.PDF• J. J. Barnard, “Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter” …RPAP039/RPAP039.PDF

• R. C. Davidson, “Multispecies Weibel and Two-Stream Instabilities for Intense Ion Beam Propagation Through Background Plasma” …FPAP026/FPAP026.PDF

• I. Kaganovich, “Ion Beam Pulse Interaction with Background Plasma in a Solenoidal Magnetic Field” …FPAP028/FPAP028.PDF

• P. K. Roy, “Initial Results on Neutralized Drift Compression Experiments (NDCX) for High Intensity Ion Beam” …FPAE071/FPAE071.PDF

• C. H. Thoma, “LSP Simulations of the Neutralized Drift Compression Experiment” …FPAE077/FPAE077.PDF

Backup


NDCX II design goals

Beam species: Na A=23Ion energy= 23.5 MeV ( =0.047)

Final spot radius = 1 mmFinal pulse duration < 1 ns

Total charge in bunch = 0.1 CEmittances: nx nz < (2.3 mm mrad) x (33 mm-mrad)

Target requirements dictate design goals of near-term HEDP accelerator (NDCX II)

0.01

0.03

0.1

0.3

1.0

3.0

10.0 eVkT=

To

tal

ch

arg

e (C

)

€

rspotmin2 = 2εf

δp

p aftercompress

=fεnxεnz3β 3cτ

nx = normalized transverse emittancenz = normalized longitudinal emittance f = focal length = 0.7 m for B=15 T , 23.5 MeV Na = final bunch duration = 1 ns= final ion velocity/c

Focal spot radius rspot depends on bothtransverse and longitudinal emittance

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