# Presentation: 631224

## Highly Compressed Ion Beams for Warm Dense Matter Science*

**Alex Friedman****1,2****,**** ****John J. Barnard****1,2****, Richard J. Briggs****7****, Debra A. Callahan****2****, George J. Caporaso****2****, C. M. Celata****1,3****, Ronald C. Davidson****1,4****, Andris Faltens****1,3****, Larry Grisham****1,4****, David P. Grote****1,2****, Enrique Henestroza****1,3****, Igor Kaganovich****1,3****, Edward P. Lee****1,3****, Richard W. Lee****2****, Matthaeus Leitner****1,3****, B. Grant Logan****1,3****, Scott D. Nelson****2****, Craig Olson****1,5****, Gregg Penn****3****,  Lou Reginato****1,3****, Tim Renk****5****, David Rose****6****, Andrew Sessler****1,3****, John W. Staples****1,3****, Max Tabak****2****, Carsten Thoma****6****, William Waldron****1,3****, Dale R. Welch****6****, Jonathan Wurtele****3****, Simon S. Yu****1,3**

**1. Heavy Ion Fusion Virtual National Laboratory**
**2. Lawrence Livermore National Laboratory, University of California, Livermore CA**
**3. Lawrence Berkeley National Laboratory, University of California, Berkeley CA**
**4. Princeton Plasma Physics Laboratory, Princeton NJ**
**5. Sandia National Laboratories, Albuquerque NM**
**6. Voss Scientific, LLC, Albuquerque NM**
**7. 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. BP1.00081**
**47th Annual Meeting of the APS Division of Plasma Physics, Denver,  Oct. 24-28, 2005**

## Abstract

- The Heavy Ion Fusion Virtual National Laboratory is developing the intense ion beams needed to drive matter to the High Energy Density regimes required for Inertial Fusion Energy and other applications. An interim goal is a facility for Warm Dense Matter studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target “foils,” which may in fact be foams with mean densities 1 to 10 percent of solid. This approach complements that being pursued at GSI Darmstadt, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the beam requirements for Warm Dense Matter experiments.  We discuss neutralized drift compression and final focus experiments and modeling.  We describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally. Finally, we discuss plans toward a user facility for target experiments.

## 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 ******** 10****11**** J/m****3**** ****; ********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

**Accessible**
**region using**
**beams in near**
**term**

**Region is part of**
**Warm Dense Matter (WDM) regime**
**WDM lies**
**at crossroads**
**of ****degenerate**
**vs. classical**
**and ****strongly**
**coupled vs. **
**weakly coupled**

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

- _Terrestial_
- _planet_

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

**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/cm****3****)**

**T (eV)**

******(g/cm****3******

**Critical point unknown for many metals, such as Sn**

**R. Lee plot, showing**
**contours**
**of 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). ]

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

**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**

_***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](http://hifweb.lbl.gov/public/hedpworkshop/tableofcontents.html)_

**Solenoid confines the slowed, high line-charge beam**
**Other approaches are possible**

**Beam requirements**

## 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 | 1.810-3 | 1.410-4 | 2.810-3 |
| Momentum Spread p / p |  210-3 |  710-4 |  0.015 |

- Na+ (A = 23), total charge = 0.1C  (61011 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

**Notes:**
We are using normalization: enz = 12 beta [<z^2><z'^2> - <zz'>^2], so that for a 1D uniform distribution in z and z', the the emittance is just enz = beta L Delta v/v, where L and Delta v/v are the full width of the respective distributions.
So for an edge value of the length L and an rms value of delta p/p, enz becomesenz 
= Sqrt[12] beta L <delta p^2/ p^2>^(1/2)  (at injector)   
 = 3.46 * 0.01 * 0.5 * 2 *10^-3    = 35 mm-mrad
(Note we need to use beta of the injector not final beta to get the right answer.)

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

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

**Neutralized Focusing**

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

**Plasma plug**

- FWHM=6.6 mm

- FWHM=2.2 mm

- FWHM=1.5 mm

- 0

- 1

- 95%
- neutralized

- 6 mA    Plasma density = 2 x 1011 /cm3

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

**Plasma plug &**
**volume plasma**

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

**300 kV Marx Generator**

**Ion Source**

**Focusing**
**Quadrupoles**

**Diagnostics**

**Diagnostics**

**Tilt Core**

**Neutralized Drift**
**Compression 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

**0**

**100**

- Time (ns)

## 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

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

**October workshop identified 5 approaches **_[http://hifweb.lbl.gov/public/hedpworkshop/toc.html](http://hifweb.lbl.gov/public/hedpworkshop/tableofcontents.html)_

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

**1 eV target heating**
**>0.1 ********C of Na****+**
**24 MeV Bragg peak**

**Short Pulse**
**Injector**

**Solenoid**
**Focusing**

**PLIA**
**Acceleration**

**Neutralized**
**Compression**

**Final**
**Focus**

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

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

- PAC05: Briggs Henestroza Waldron
- 	Caporaso
- 	Nelson
- 	Roy

**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 Pumping

**First low voltage bench test**

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

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

- z(m)

- z(m)

- z(m)

- z(m)

- z(m)

**V (kV)**
**E****x ****/ 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)**

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

**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

## V(z) along the air-dielectric helix

**Input end**

**Input**

**Output end**

**V(z) along the air-dielectric helix**

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

**Helix accelerating **
**structure **
**(in ‘snowplow’ mode)**

**Matching **
**solenoids**

**Source**
**(accel/decel)**

- Beam species K+
- Total charge 0.1C
- nxnz=(1mm-mrad) x (8mm-mrad)
- 	[       of NDCX-II design goal]

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

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

- Decelerates the
- beam head

- Time (   s)

- Negative pulse accelerates tail
- more 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

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

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

***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-1d**
**Pulse-Line Ion Accelerator (Helix)**

**NDCX-1a**
**Neutralized Drift Compression**

**NDCX-1b**
**Solenoid Transport**

**Inter-changeable**

## A sequence of steps leads to an instrumented user facility

**(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

## Target requirements dictate design goals of 

**NDCX II design goals**
**Beam species:  Na  A=23**
**Ion energy= 23.5 MeV  (******** =0.047)**
**Final spot radius = 1 mm**
**Final pulse duration < 1 ns**
**Total charge in bunch = 0.1 ********C**
**Emittances: ********nx**** ********nz**** < (2.3 mm mrad) x (33 mm-mrad)**

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

****nx**** = normalized transverse emittance**
****nz**** = 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 ***r**spot*** depends on both**
**transverse and longitudinal emittance**