# Presentation: 853109

## Opportunities in R&D for Heavy-Ion Beam Fusion Energy

***This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley and Lawrence Livermore National Laboratories under Contract Numbers DE-AC02-05CH1123 and W-7405-Eng-48, and by the Princeton Plasma Physics Laboratory under Contract Number DE-AC02-76CH03073.**

**B. Grant Logan**
**Heavy Ion Fusion Science Virtual National laboratory* **
** ****Tuesday August 1****3:00 p.m. to 4:30 p.m.****Bldg. 543, Grand Canyon Room 1258**

## What we mean by Heavy-Ion-Fusion R&D, as opposed to the current DOE program limited to heavy-ion-beam and beam-plasma science:

**Beams at high current and sufficient brightness to focus**

**Long lasting, low activation chambers that can withstand 300 MJ fusion pulses @ 5 Hz**

**High gain targets that can be produced at low cost and injected**

*********Coordinated R&D on heavy-ion drivers, chambers and targets that have to work together for inertial fusion energy (IFE).***

**(Concept of Heavy Ion fusion-**
**Slide from Snowmass 2002)**

## Laser and pulsed-power drivers have advanced significantly, but the reasons HIF was historically preferred by DOE reviews still apply:

**High energy particle accelerators of MJ-beam energy scale have separately exhibited intrinsic efficiencies, pulse-rates, average power levels, and durability required for IFE. *****Advantage of being able to build upon a credible high energy particle accelerator experience base.***
**(b) Thick-liquid protected target chambers with 30 year plant lifetimes, compatible with indirect-drive target illumination geometry to be tested in the National Ignition Facility. *****Avoids the need for a long fusion materials development program.***
**(c) Focusing magnets for ion beams avoid direct line-of-sight damage from target debris, neutron and gamma radiation. *****Detailed studies show shielded final focus magnets can last for many full power plant years of operation.***
*** ***
**(d) Several heavy ion power plant studies have shown attractive economics (competitive CoE with nuclear plants) and environmental characteristics (no high level waste; only class-C low level waste). *****Molten salt (HYLIFE-II type) chambers cost < $10 M / GW******th************ multi-unit plants sharing one driver************ < 3 cts /kW******e******hr ***
**(e) HIF targets driven indirectly by x-rays within hohlraums can utilize much of the same target physics data to be generated by the NNSA ICF program. *****Leverages largest NNSA supported target physics effort on indirect drive.***
**(f) Cryogenic-DT fuel capsules in HIF targets would be protected by the surrounding hohlraum when injected into hot IFE chambers. *****Eases target injection.***** **

## On 12-12-03, SLAC Director Burt Richter wrote to the DOE Fusion Energy Advisory (FESAC) panel considering fusion development:

**“****The Office of Science funds heavy ion fusion (HIF) while Defense Programs funds the laser and pulsed-power applications.  This has had the unfortunate result of putting the vast majority of inertial fusion funding into lasers and pulsed-power while a whole series of review panels, going back to the late 1970’s, have consistently indicated that HIF has the most promise as a source of energy.  Here is a brief list:**
**The 1979 Foster Committee**
**The 1983 Jason Report (JSR82-302) **
**The 1986 National Academies of Sciences Report of March**
**The 1990 Fusion Policy Advisory Committee report (Stever Panel)**
**The 1993 Fusion Energy Advisory Committee (Davidson Panel)**
**The 1996 FESAC report (Sheffield Panel)**
**...****..”**
**            *****(Copy of Richter letter is available upon request)***

## What critics of HIF say (and what we are doing about it)

**After 25 years of research, you never tried to hit a target. *****We invented plasma neutralized beam drift compression and focusing (NDC) in 2003, demonstrated > 50 X bunch compression to 3 ns in 2005, and plan our first target experiments beginning 2007-2008.***
**We don’t need another fusion concept with multi-billion-dollar projected power plant costs. *****A multi-chamber hydrogen production study in 1994 showed low CoE < 3cts/kWehr sharing a driver. We are also studying innovative HIF target, focusing, and accelerator concepts to reduce driver voltage and total capital cost by 10X.***
*** ***
**Your demand for costly prototype accelerators up front make your development path unaffordable given the risks. *****We are developing and testing very low cost modular linacs for our 2008 WDM target experiments which point to a lower cost development path for HIF.***
*** ***
**Why is the US the only country interested in HIF? *****Classification of targets used to be a barrier, but since declassification, interest in HIF collaboration has grown in Germany, Japan, and Russia.*****   **

## Current ion accelerators compared to an HIF driver

|  | NDCX/HCX* | GSI-SIS18 | RHIC | HIF driver |
| --- | --- | --- | --- | --- |
| Ion energy | 300 keV     /1.8 MeV (K+) | 70 GeV 
(U 28+)  | 500 GeV
(Au) | 0.2 to 10 GeV
(Ne+ to Pb+) |
| Beam power | 400 kW       /72 MW
(in 3 ns) | 350 MW
(in 130 ns) | 100 GW 
(10 s dump) | 4 TW / beam
X100 beams
(in 8.2 ns) |
| Beam energy | 1.2 mJ 
/ 0.2 J | 45 J | 1 MJ
(total dump) | 3.3 MJ |
| Space charge
/KE (final) | High
5 x 10-2 | Very Low
10-9 | Negligible
 | High to low
10-1 to 10-5 |
| Ion range | Low
(~ 3 m foil)
0.0001 g/cm2 | High
(> WDM target)
10 g/cm2 | Way too high
for IFE
10,000 g/cm2 | IFE target
requirement
0.03 g/cm2 |

*** if HCX were converted for NDC compression**

## The FESAC and HEDP Task Force ten year plans for heavy ion beam science requested budgets twice our FY07 level. But, HIF target and chamber science is missing. 

**Fig 3.1 , p. 33 **
**(from the 2004 **
**Interagency**
**Task Force report)**

## From Ed Synakowski  (HIF06 St. Malo talk slide):

## NIF will test key hohlraum x-ray 

**NIF will test key hohlraum x-ray **
**transport and capsule physics that **
**will be relevant to a variety of IFE **
**approaches, *****but particularly to***
***indirect drive HIF ***

## A personal view: competition forces us to improve our 2002 HIF development path

**FESAC Dev Path Demo decision**

**HIF could be expedited with a modular linac approach**

**Notes:**
Here’s the overall cost and schedule plan for heavy-ion fusion, including key decision points. I only have time to point out some key points about this plan.
It meets the DEMO goal of net power by 2037, assuming indirect drive and thick liquid walls work.
The prominent cost spike is for the 5.5 MJ ETF driver based on a conservative estimate of accelerator and target requirements, as I said before.
The IFE community agrees to down-select to one ETF/DEMO facility, so to help the panel parse the entire program costs, I list all the HIF costs up to the key decision point for the ETF in 2022. Those costs would be added to those of other IFE approaches, but after only one chosen ETF/DEMO sould be included.
This plan includes all the liquid-chamber test facilities that Per mentions (some of whom are included in Charlie Baker’s VLT facility lists), but because some of those are shared, or generic, to several approaches, I include only these specific cost fractions of those facilties.

## To the extent enabling science for HIF can be supported, we have issues to address (holes in science areas important to heavy ion fusion):

**HIF drivers: Since 2003 we have gained much understanding and excellent simulation tools for e-cloud physics, but we need to update e-cloud effects in conceptual HIF driver designs.**
**HIF targets: Since 2003 progress in fast ignition and direct drive laser IFE has improved prospects for IFE drivers below 1 MJ energy. We need more HIF target design innovation to lower drive energy.**
** **
**HIF chambers: Since 2003 we have developed neutralized compression and focusing for HEDP experimental chambers, but we need fully-integrated neutralized drift compression, final focusing and chambers with adequate stand-off for HIF power plants.**

***IFE may be included in a new FY07 Snowmass for 10-year fusion planning. The Senate calls for an HEDP (+IFE?) roadmap by March 2007. We at least need to be prepared to update plans.***** **

## We also have many affordable opportunities to pursue in HIF driver, chamber and target science

**1. We can complete the knowledge base needed to evaluate both quadrupole as well as solenoid based HIF drivers:**
**-First data on e-cloud effects in solenoids.**
**-HCX experimental plans to test halo scrapers and induction gaps to mitigate e-clouds in magnetic quads (modest incremental cost)**
**2. Optical drive solid state switching + fast kickers (LLNL Beam Research innovations) may enable linac multi-pulsing and time-dependent corrections for compression velocity tilts******** improved target pulse shaping capability with fewer beams (test on NDCX).**
**3. Advanced HIF target design plus NIF & Z data may lead to lower HIF driver requirements (1 to 2 MJ?)**
**Compact liquid vortex chambers with embedded magnetic field may allow higher pulse rates (20Hz?) and shorter focal lengths ********smaller focal spots (can use existing UCB lab facility).**
**5. Updated systems studies for HIF power plants**

**       ****HIF driver R&D opportunities**

## Challenge of electrons in HIF drivers: use them or lose them

**The US heavy ion program is pursuing warm dense matter target physics at the Bragg peak in dE/dx, where the vacuum beam perveance would be otherwise too high to focus. Also, IBEAM studies (Meier, HIF2004) much lower cost linacs possible with higher charge/mass ions******** space charge must be neutralized *****before***** longitudinal and transverse compression *****(Learn to use electrons)***
**Theory/simulations of beam-plasma instabilities, and experience with focusing high perveance beams in plasma in NTX (2004) indicate deleterious instability effects can be minimized in certain regimes.**
**Electron cloud effects appear ubiquitous in high intensity ion accelerators: we must learn to avoid unwanted electron neutralization to << 1 part in 100, or not generate them << 10****-4**** beam loss per meter*****  (Learn to lose electrons)***** **

## _x0003__x0016_

**Slope ~1 mm/μs**

**Electron and gas cloud modeling critical to all high current accelerators, including HEP: LHC, ILC **
**...****and future HEDP/fusion drivers: NDCX-II, IB-HEDPX .**
**(Art Molvik, Ron Cohen, Jean Lu-Vay)**

- WARP-3D
- T = 4.65s

**Oscillations**

**Electrons bunching**

**Beam ions hit end plate**

**e****-**

**0V               0V           0V/+9kV              0V**

**Q4**

**Q3**

**Q2**

**Q1**

***200mA K******+***

***200mA ***
***K******+***

**       ****Electrons**

**6 MHz oscillations in ****(C)**** in simulation AND experiment**

**(c)**

**0.            2.      time (********s)       6.**

**0.**
**-20.**
**-40.**

**I (mA)**

******Four HCX magnetic quadrupoles**

## We have long realized that e-cloud effects could be important, but only recently gained the tools to calculate e-cloud effects.

**We initiated the HCX in 1995 at LBNL to study these transport issues, but we did not get magnetic quad transport data until 2003 (budget cuts). Multi-species WARP-3-D PIC simulations needed to model ions and electrons self-consistently were not available until 2004. **

- ...

**We need to check e-cloud effects on the last US HIF driver study “An updated point design for heavy-ion fusion (Yu, et.al. FS&T, 2002)**

## Revisiting multi-beam quad arrays for HIF will require accurate predictive 3-D e-cloud simulation models and effective mitigation.

**HCX uses four pulsed magnets from the 2000 IRE-HIF Quad Array Prototype**

**HCX neutralization data to date:**
**All e-suppression off:**
**     ****Beam ~ 100% neutralized (last quad)**
**End suppressor only on:**
**     ****Beam ~ 20 % neutralized**
**Suppressor + clearing electrodes on**
**     ****Beam ~ 7 % neutralized (Art Molvik)**

**The High Current Experiment (HCX) at LBNL (1 MeV, 180 mA K****+**** , 4 ********s beam)**

## System studies show that driver cost is very sensitive to channel fill factor. Need to model e-cloud effects, possibly with clearing electrodes. 

**IBEAM results:**

**(fixed number of beams, initial pulse length, and B)**

**Robust Point**
**Design (2.8 B$)**

**range being explored**

**System studies show that driver cost is very sensitive to channel fill factor. Need to model e-cloud effects, possibly with clearing electrodes. **

## Initial solenoid transport experiment in NDCX using a 25 mA, 300 keV K+ ion beam through two 3T solenoids 

**Two-solenoid NDCX Transport Experiment**

**Beam Image**

**WARP PIC Model**

**Diagnostics and modeling are being carried out to understand transport including e-cloud, and gas effects in four solenoids. (See HIF06 talks by Seidl and Roy) We will compare transport of high perveance beams in solenoids and quads.**

## E-C

**We have started to measure and simulate e-cloud effects in NDCX solenoids August 2006, to compare with quadrupoles (Art Molvik)**

## Work in progress: we are evaluating ways to apply what we learn from our HEDP research towards heavy ion fusion energy

******Key enabling advances that will help **_**both HEDP and fusion**_**:**
**Neutralized drift compression and focusing.**
**Time-dependent correction for improved achromatic focusing.**
**Multi-pulse longitudinal merging and pulse shaping.**
**Fast agile optically-driven solid state switching.**

**Sketch of a modular, multi-pulse heavy ion driver. Pulses **
**overlap at the target******** 500 TW peak power in 2 ns ******** < 1 MJ driver?  (TBD)**** **

## Comparing 1MJ HIF linac driver example cross-sections 

**Multi-beam Quad (MQ) driver, an RPD-like design scaled down to produce 1MJ of 4 GeV Bi+  ions in a single pulse.**

**Modular Solenoid (MS) driver system, one of 40 linacs, to produce 1MJ total of 500 MeV Ar+8 with five pulses per linac.**

**(Recent IBEAM systems code work, submitted to ****Nucl. Instr. and Meth. Phys. Res., July 2006** **)**

## Comparison of 1 MJ HIF drivers based on a modified IBEAM systems code (no-e-cloud) show benefit of NDC

| Driver type | Low q/A MQ Bi+1 |  Hi q/A MQ Ar+8 | Hi q/A MS Ar+8 |
| --- | --- | --- | --- |
| Etotal  (MJ) | 1 | 1 | 1 |
| # Pulses | 1 | 3 | 5 |
| # Linacs | 1 | 1 | 40 |
| # Bunches | 120x1 | 150x3 | 40x5 |
| Range (g/cm2) | 0.03 | 0.03 | 0.03 |
| Timax (MeV) | 4000 | 600 | 600 |
| Timin (MeV) | 3300 | 500 | 500 |
| Voltage (MV) | 4000 | 75 | 75 |
| Length (m) | 2900 | 300* | 75x40 |
| Ibinjection (A) | 0.075 | 5.2 | 12 |
| Ibfinal (A)  | 11 | 176 | 2000 |
| Cores (tons) | 21,400 | 1,930 | 2,400 |
| Efficiency** | 0.21 | 0.55 | 0.28*** |

- *includes ESQ section to 100 MeV **Efficiency estimated on core losses only
- *** core efficiency would be 50% at 3 pulses instead of five

**Russians have demonstrated needed high q/A ion sources using 500 kW pulse gyrotron ECR**
**[reference S. V. Golubev, S. V. Razin, and V. G. Zorin, Rev. Sci Inst. 69 (1998) 634.]**

## Our next step towards HEDP would demonstrate high q/A >0.1 ion acceleration and focusing (Li+1 q/A=0.14 vs driver Ar+8 q/A=0.2)

- TARGET
- CHAMBER

- 14 ATA-II
- INDUCTION CELLS

- DIAGNOSTICS BOXES
- AND
- PUMPING

- LOAD-AND-FIRE
- INJECTOR

**(E. Henestroza, J. Barnard, W. Waldron, M. Leitner)**

**Short pulse Accel- Decel injector mode allows multi-pulse tests **

**We have most of the parts for the injector, solenoids and accelerator**

**Fast optically-gated solid state switches should enable multi-pulsing **
**(Caporaso, LLNL)**

## High gradient insulators can become cheap in 30 years

**Steve Sampayan, George Caporaso, LLNL**

**        ****Opportunities in targets and chambers**

## Can we find a better compromise for small DEMO target spot size and 

**Can we find a better compromise for small DEMO target spot size and **
**gain at 1.5 MJ between scaled down close-coupled and hybrid?**

**Callahan’s HIF04 NIMA paper for HYBRID**

**Can we morph a target between the above two types at 1 to 1.5 MJ, **
**To obtain a gain 20 to 30  @ > 1 mm spot size?**

## Ed Lee is working on NDC focusing schemes offering dramatically smaller driver/chamber interfaces with 20 beams/end @ 3-5 pulses = 120 to 200 bunches for target pulse shaping. 5X higher peak beam power enabled.

**Ed Lee is working on NDC focusing schemes offering dramatically smaller driver/chamber interfaces with 20 beams/end @ 3-5 pulses = 120 to 200 bunches for target pulse shaping. *****5X higher ***_***peak***_*** beam power enabled.***

**RPD multi-beam vacuum quadrupole final focus arrays dwarf HYLIFE chamber. Demo version needed 5.5 MJ ETF/DEMO chamber for 280 MJ yield =88% of RPD.**

**Can we find target solutions for 1 to 2 MJ driver energy with 40 MJ yields for HIF DEMO exploiting new pulse shaping capability with NDC, and can we develop 10 to 20 Hz pulse rate vortex chambers with < 10 cent targets for economical  DEMO net electricity?**

**(****Work of Ed Lee)**

**(600MeV)**

## Absent space charge within background plasma, Ed Lee’s Mathematica model for axisymmetric vortex chamber magnetic fields including aberrations shows sub-millimeter spots for Ar+8

**Assumes 10% upstream coherent velocity ramps for compression, and a transverse normalized emittance of 1 mm-mr.  **

## Development of liquid protected chambers can be done with modest budgets using scaled, hydrodynamically-equivalent water flows. Vortex=potential high pulse rates?

**Development of liquid protected chambers can be done with modest budgets using scaled, hydrodynamically-equivalent water flows. Vortex=potential high pulse rates?**

_**UCB experiments**_

**(3) Turbulent mixing absorbs high surface heat fluxes**

**(1) Short average flow paths and liquid resident times**

**(2)Many inlets **
**and outlets**

**Given fast (<1 to 10 ms) plasma clearing of cavity: **
**(1)+(2)+(3) = **_***very high potential chamber thermal power densities***_

## Serendipity: with special overcoated hohlraum targets, the new magnetized vortex chamber is ideal to confine target plasma well enough to neutralize the beam on subsequent shots (even after 20x decay)

**Assume ~1 m****3**** cavity volume, 2 m****2**** liquid cavity surface, ~ 40 MJ magnetic **
**field energy damps turbulence from 30-40% of fusion yield captured into a special target coated with a thick Flibe layer**

**Magnetized resistive plasma**

**Liquid**
**Flibe**

**Dense **
**vapor**

-    Constant pressure (r) to liquid (after a few bounces)

- Density gradient

- Temperature gradient

**Opportunities in systems studies of integrated HIF power plants and development pathways**

## We have three hopes for ultimate HIF CoE < CoE fission

**Beam switching into many cheap, thick-liquid chambers *****(or equivalently, higher pulse rate vortex chambers)***** *****(Logan, Moir, Hoffman “ Fusion Tech. 1995 “Requirements for low cost electricity and hydrogen fuel production from multi-unit inertial fusion plants withed a shared driver and target factory” shows this approach beating multi-unit fission CoE above ~***_***4 GWe***_*** total plant outputs, for drivers < $1.2B total capital cost (~<$500M direct)***
**Fast clearing vortex chambers supporting > 20 Hz pulse rates for > 5 GWe outputs, with < $0.5B total capital cost driver and < 10ct targets**
** ****Exploit unique, low cost direct conversion, e.g., CFAR-II MHD**

## At large enough plant outputs, cheap enough drivers, liquid chambers and targets ultimate fusion CoE can beat future fission CoE because of lower fuel costs.

**Latest modular solenoid drivers **
**with  NDC might cost less than **
**$500M direct @ 3 MJ**

*********requires solution to “1000-spaghetti-***
***beamlines” switchyard problem!***

**John Woodworth’s target factory model **
**shows cost/target continuing to drop **
**with very high production rates**

**Higher ********T with **
**Vortex chambers?**

**MHD BoP?**

**Modular **
**Linac **
**driver?**

## High leverage innovation: the cheapest way to reduce CoE is through higher chamber pulse rates (if we can do it!) 1 eV plasma flows out at 8 km/s!

**High leverage innovation: the cheapest way to reduce CoE is through higher chamber pulse rates (if we can do it!) 1 eV plasma flows out at 8 km/s!**

**Add  2-4 cm material around hohlraum OD to make lower temperature confined plasma, ********reduced liquid surface ablation!**

## This IRE example with NDC could be one of the 40 driver linac modules, delivering 5 programmable pulses delivering a total of 25 kJ of 500 to 600 MeV Argon ions, with up to 12 TW of peak beam power for beam-target radiator tests and vortex chamber dynamics experiments. 

**Not shown in **
**this IRE drawing **
**is a fast ramping **
**kicker needed **
**for time-**
**dependent **
**focusing **
**corrections for < **
**1 mm spot target **
**experiments. Ed **
**Lee has an **
**NDCX-II kicker **
**concept that **
**could apply here.**

## A May-1-06 systems analysis (Small Modular HIF Driver) describes one possible solution for improving HIF driver development path.Low yield targets + high pulse rate vortex chambers might satisfy “Demo-small,-then grow large” desired development path objective for low unit cost electricity & hydrogen fuel production.

## Modular solenoid linacs HIF development path competitive with other IFE approaches? 

## Critical issues we need to work on

**Demonstrate control of electrons- keeping them out of the accelerator, while ensuring virtually 100 % neutralization everywhere beyond the accelerator to the target.**
**High power pulsed ECR sources for 10-A level high q/A > 0.1 ion sources.**
**Develop agile waveform control and optical-drive solid sate switches for multi-pulse linacs and time dependent focusing.**
** **
**Develop efficient drivers and targets @ 1 MJ drive energy for a small, < $500M DEMO with ********G >10: e.g. G > 20 @ ******** > 0.5, or G > 40 @ ********>0.25.**
**Develop magnetized liquid vortex chambers compatible with low yields, > 10 - 20 Hz pulse rates, and plasma neutralization.**

**Backup slides**

## We are evaluating time-dependant focusing for NDC

**Concept sketch (G. Logan 9-21-05) **

**Ed Lee has evaluated examples**
**NDCX-II: 20 to 24 MeV Na****+9**
******n**** = 2.3 mm-mr,  ***********v/vtilt *****= 0.1**
**L****drift**** = 4m, B****drift****=0.6 T**
**B****focus****= 15 T, ********focus**** = 150 mr**
**B****pulsed **** = 0.8 T, r****spot**** = 0.4 mm**
**HIF-NDC: 600 to 730 MeV K****+19**
******n**** = 5 mm-mr,  ***********v/v******tilt*****=0.1**
**L****drift****= 400 m, B****drift****= 0.02 T**
**B****focus****= 0.3 T, ********focus**** = 6 mr**
**B****pulsed **** = 0.13 T, r****spot**** = 4 mm**
**9 meter focal length**

## Adding accelerator ion beam R&D to exploratory fast ignition research portfolio prudent risk management

**Unstable electron beams may not deposit where laser is pointing.**

**Ion beams dE/dx along straight lines to the Bragg peak**** **

***Magnetic pinch region ***
***near target ***
***may be needed***

**Petawatts of **
**photons are **
**available for**
**FI experiments**

**Petawatts of **
**ions await **
**development for **
**FI experiments**

**Focusing magnets **
**IFE durable**

**Focusing paraboloid **
**not IFE durable**

## History (cont.) Debbie Callahan (LLNL) assessed heavy ion fast ignition target requirements in 1998

## We have begun using Hydra to explore accelerator requirements to study ion-beam driven Rayleigh Taylor instability (John Barnard, LLNL)

**We have begun using Hydra to explore accelerator requirements to study ion-beam driven Rayleigh Taylor instability (John Barnard, LLNL)**

****
**t= 0.4 ns**

****
**t= 1 ns**

****
**t= 5 ns**

****
**t= 10 ns**

**Beam**

**T**
**t= 0.4 ns**

**T**
**t= 1 ns**

**T**
**t= 10 ns**

**T**
**t= 5 ns**

**g/cm****3**

**eV**

**23 MeV Ne, 0.1 ********C, 1 ns pulse (NDCX II) impinges on  100 ******** thick solid H, T=0.0012eV,            ******** =0.088 g/cm3; ****No density ripple**** on surface******** ****blow-off stably accelerates slab**** **

## When initial surface ripple is applied, beam-driven Rayleigh-Taylor growth is seen. [Kawata (Japan) proposes stabilization by GHz beam modulation].   

**When ****initial surface ripple**** is applied, beam-driven Rayleigh-Taylor growth is seen. [Kawata (Japan) proposes stabilization by GHz beam modulation].   **

****
**t=0.4 ns**

****
**t=1 ns**

****
**t=3.5 ns**

****
**t=5 ns**

****
**t=7.5 ns**

****
**t=10 ns**

**T**
**t=0.4 ns**

**T**
**t=1 ns**

**T**
**t=3.5 ns**

**T**
**t=5 ns**

**T**
**t=7.5 ns**

**T**
**t=10 ns**

**Would hyper-velocity ion direct drive be feasible with dynamic stabilization?**

## If neutralized drift compression and focusing of low range ions (0.001- 0.004 g/cm2) to 1 ns, 1 mm spots can be achieved for HEDP, then ion-direct-drive-impact fast ignition*  may be feasible. 

**Hydrogen -best ablator for ion-direct-drive (Tabak)**
**Implosion velocity  V****imp**** =******** Cs ln (M****H****/M****DT****)**
**Sound speed   C****s**** = [(Z+1)kT****H****/(Am****p****]****0.5**
**T****H****=1 keV, (Z+1)/A =****2**** ****for hydrogen**** (=0.5 for plastic!)**
**M****H****/M****DT**** = 5, ******** ~1.5   ******** V****imp**** =10****6**** m/s, ~250 kJ ion**
**beam drive energy @ ~2 ns: adequate for ignition?**

**Schematic of fast impact ignition target: **
**-ion indirect drive for fuel compression **
**-****ion direct drive for fast impact ignitor**

****M. Murakami (ILE, Osaka) described impact ***
***ignition with laser direct-drive for a cone-igniter ***
***segment at HIF04. Here we consider ion-***
***direct drive in the cone.***

***NDCX may study DD RT-stability in 1-D***