# Presentation: 777124

**Heavy Ion Fusion-a Future Perspective**

**   ****E. Michael Campbell**
**    ****PPPL, June 7, 2004**

## Presentation Outline

- Present Fusion landscape
- Why HIF
- Challenges
- Opportunities
- Path Forward

## Fusion Facts

- No Administration commitment to rapid development of Fusion energy
- Budget deficit is increasing problem (approaching % of GDP seen in late 1980’s) and no “cold war windfall”
- War, Homeland security are priorities
- Energy Priorities are “nearer term” solutions
- Hydrogen (Hydrogen already at ~11 Mtons/year and annual growth  is ~10%)
- Fission
- Viewed as Science Program with energy S&T deferred to “after Burning plasmas or Scientific feasibility” demonstrated

**NGNP at INL**

## Fusion Facts (cont’d)

- ITER and not IFE initiative will be OFES focus for next decade
- IFE not supported (“we can’t afford two approaches today”) by DOE,  OFES or OMB
- OFES and OS view is ICF/IFE is NNSA (NNSA$>>OS$) responsibility
- OFES priority after ITER is to better exploit existing facilities (**present run time on 3 major OFES facilities is ~14 weeks)**
- Some OS interest in High Energy Density Physics

## ICF S&T advances, funding and controversy are made possible by its Multiple Missions: HIF lies in the Energy and S&T plane

**Stockpile**
**Stewardship**

**National **
**Security**

**Science/technology **

**Energy(****National **
**Security)**

**ICF**

## An IFE initiative should be catalyzed by Ignition and High Performance Implosion Results 

- Ignition will catalyze IFE interest and may lead to broad support for an IFE initiative
- ICF/IFE community must maintain ignition focus on NIF (~2010)
- Implosion Experiments will have an impact if successful
- Cryogenic, low , DT Direct drive implosions on Omega (~2006)
- Integral Fast Ignition experiments on FIREXI and Omega-EP (ZR and PW?)
- Implosions on Z

**And HIF........................................**

## The Motivation for HIF has not changed

- HIF accelerators have attractive efficiency, rep-rate and durability for IFE
- Large accelerator community experience that is relevant
- Focusing optics are more robust to fusion chamber environment (radiation/debris) than lasers
- < 4 illumination for targets allows for neutronically thick liquid walls
- NNSA indirect target physics program (and FI research (OFES & NNSA))

**BUT..............................**

## HIF Development faces significant challenges

- Development path is costly and has not been viewed as symbiotic with other ICF/IFE programs
- Little/no target experiments
- Advantages are “too far off” to motivate IFE support today
- Competition from HEDP facilities

## What Would Marshall say?

**What Would Marshall say?**

## Innovation and a broad program approach will  position HIF for a future IFE initiative  

**Accelerator**
- Increase modularity (reduce “unit size”)
- Beam manipulations in space and time (like lasers!)
- Lasers :
-  temporal pulse shaping
- CPA (extreme temporal compression -103-104)
- Phase plates and deformable mirrors
- Pulse Power developing analogous capabilities
- Develop “average power” experiments
**Target design and fabrication**
- Advanced simulations
- Targets to compensate for driver limitations
- Fast Ignition
- Develop “average power experiments”

## Innovation and a broad program approach will  position HIF for a future IFE initiative

**Utilize existing facilities**
- Implosions to exploit HIF relevant concepts
- Symmetry control (Shims)
- Low temperature ablators ( Be:Cu)
- Rad-Hydro with foams
- Ions from short pulse lasers
- Ion-plasma interaction
- Neutralization physics (?)
- Source development required!
**Synergistic Engineering Physics and technology with Pulse Power**
- Neutronically thick liquid walls
- Reactor concepts
- Driver technology

**There is time to innovate................**

## IFE  requires:

**•**_**Drivers**_
** **
**   **

**Z-R**

**OMEGA EP**
**      ****& Nike,Trident,..**

**NIF**

**•**_**Simulations**_
**  **

**•**_**Target S&T**_
** **

**3D rad.-hydro **
**Simulation of  **
**igniting target**

**Double shell**
**target**

##                 Accelerators

## Improved HIF Beam  Manipulations are required ! 

**Pulse Shaping for Robust HIF Point Design (Indirect Drive) 120 beams, 7MJ**

**Laser Pulse Shaping (Direct Drive) ~60 beams ~2 MJ**

**Improved HIF Beam  Manipulations are required ! **

## Innovations

_***Beam Production***_

**Accel-decel injector** + compression

_***Transport***_

**Solenoid transport** of **large-perveance** heavy-ion beams

_***Longitudinal Compression***_

_***Transverse Focusing***_

**Neutralized** drift compression

**Plasma lens, **
**Plasma channel pinch transport**

##  LSP simulations of neutralized drift and focusing show significant spatial and temporal compression

- (cm)

- Axial compression **120 X**
- Radial compression to 1/e  focal spot radius **< 1 mm**
*Beam intensity on target increases by ****50,000 X*****.**

**R(cm)**

- Ramped 220-390 keV K+ ion beam injected into a 1.4-m long plasma column.
- Background plasma at **10 times** beam density (not shown).

**3.9T solenoid**

-  LSP simulations of neutralized drift and focusing show significant spatial and temporal compression

**Z(cm)**

**Experiments are essential to validate concept**!

##                 Targets

## Increased Hydro stability

**Graded Cu dopant**
**In Be shell**

** ****A small fill tube**

**IFE has benefited from Innovation in Drivers, Physics, and Target Fabrication: ****Target design and fabrication(graded Be:Cu ablators and fill tubes)**

**Increased Hydro stability**

## HIF can benefit from Innovation in Target Design and Fabrication: (Shims to control symmetry)

**Target design and Fabrication can compensate for Driver Limitations   (3D Rad-Hydro Codes are required!!!)**

- Shims

- Experiments are underway at Z to validate concepts
- Future Experiments on Omega and NIF

**HIF**

**Z**

## Fast Ignition Concepts for HIF and Z are similar

- HIF FI Concept (120 ev radiation Implosion)

- Ignitor Beam

- Pulse Power FI Concept

- Final Shell position

- Initial shell Position

##  Polar Direct Drive on NIF is an example of non-spherical “initial conditions” that may lead to ignition/gain imploded fuel assemblies)

**Baseline Approach****:**
**Move the Beams!**

**New Approach****:**
**Re-point the Beams! **

**Multi-Dimensional Calculations and 192 beams make this possible! **

##  Ions From UUL

## Protons and ions are accelerated in relativistic laser-solid interactions by three principal mechanisms

**III.  Target Normal Sheath Acceleration**
- Ei ~ 10 x Te
-  Electrons penetrate target & form dense sheath on rear, non-irradiated surface
-  Strong electrostatic sheath field ionizes surface layer (Eo ~ kT / ed ~ MV/m)
-  Rapid (~ps) acceleration in expanding sheath produces very laminar ion beam

**II.  Front-surface charge separation**
- Static limit: Ti ~ Te

## Laser-Ion diodes have very interesting characteristics but need development 

**Laser-Ion diodes have very interesting characteristics but need development**

- 50 m W + 1 m CaF2
- (900O C)

- 4% conversion of laser energy to F7+ ion beam observed !!

- 20 J, 350 fs
- 1.054 m

- Transverse emittance:  	< 0.006  mm-mrad   (
-  Longitudinal emittance:  	< keV-ns    (velocity correlated)
-  **Energy spread:****	****	****100%**
-  Bunch charge:		1011 – 1013 protons/ions
-  Source diameter:		~50 m (fwhm)
-  Charge state purity:	>80%  He-like
-  Particle current:		>100 kA  (at source)
-  Rep-rate:		determined by laser driver
-  Laser-ion efficiency:	> 1%   (4-20% observed
**Neutralization                             ~100%**

**Laser-ion diodes**

## 50 m

**PW IONs can be focused**

**50 ********m**

**200********m**

**>400********m**

**Streak images of visible Planckian emission**** **

## Al has been heated to ~23 ev by a focused laser  produced proton beam 

**Al has been heated to ~23 ev by a focused laser  produced proton beam **

**P K Patel *****et al***

**Laser to Proton conversion efficiencies ~10% were observed at Nova PW**
**Next generation of PW (2-3 kJ) may lead to ~100ev via ion heating**
** **

**T ~23 ev (7 x 10****5**** j/g)**
**(~0.2 joules from 10 joule laser)**

## Laser-Ion acceleration should be explored in conjunction with Heavy-ion Inertial Fusion program and Fast Ignitor

##                 Chambers

## HIF and Z pinch employ thick liquid walls enabled by < 4  target illumination

**Flibe Jets**

**Xray driven targets**

**Z pinch IFE**

**HIF**

**“****Reactor Physics” collaboration should be key element of Z and HIF IFE research**

## Multiple reactor chambers are a feature of Pulse Power IFE

**Z-Pinch IFE DEMO study used 12 chambers, **

**Symbiosis with HIF?**

## Innovation and a broad program approach will  position HIF for a future IFE initiative

- Accelerators
- Target design and fabrication
- Exploit existing Facilities
- Partner with Pulse power for reactor design and Engineering
- Become Champion of “average power” experiments

**Always keep sight of the end goal !**