# Presentation: 524092

## Presented at the 15th International Symposium on 
Heavy Ion Driven Inertial Confinement Fusion 
in Princeton, June 7, 2004

by

Matthias Geissel1,2, Markus Roth2,

M. Allen3, P. Audebert4, M. Basko5, A. Blažević2, E. Brambrink2, 
J. Cobble6, T.E. Cowan7, M. Cuneo1, J.C. Fernández6,
J. Fuchs4,7, J.-C. Gauthier4, M. Hegelich6, S. Karsch8

- Presented at the 15th International Symposium on
- Heavy Ion Driven Inertial Confinement Fusion
- in Princeton, June 7, 2004
- by
- _Matthias Geissel__1,2__, Markus Roth__2_,
- M. Allen3, P. Audebert4, M. Basko5, A. Blažević2, E. Brambrink2,
- J. Cobble6, T.E. Cowan7, M. Cuneo1, J.C. Fernández6,
- J. Fuchs4,7, J.-C. Gauthier4, M. Hegelich6, S. Karsch8

- Short Pulse Laser Generated
- Ion Beams for Fast Ignition

- 1Sandia National Laboratories, Albuquerque

- 2Darmstadt University of Technology & GSI, Darmstadt

- 4LULI – École Polytechnique, Palaiseau

- 7University of Nevada, Reno & GA, San Diego

- 8Rutherford Appleton Laboratory

- 3University of California, Berkeley

**TU Darmstadt**

- 6Los Alamos National Laboratory

**UN Reno**

- Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the
- United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000

- 5Inst. for Theor. and Exp. Physics, Moscow

## Intro: Combining Lasers and Ion Drivers

_**Intro**_: Combining Lasers and Ion Drivers
_**Concept**_: How Does It Work?
_**Experiments**_: Probing the Models
_**Fast Ignition**_: Some Considerations
_**New Projects**_: Perspectives at SNL

## Laser Drivers

**Laser Drivers**

-  High Power Densities
-  Good Pulse Shaping

-  Low Driver Efficiency
-  Low Repetition Rate

**Heavy Ion Drivers**

-  High Efficiency
-  Beam-Target Coupling
-  High rep-Rate

-  Lower Power
-  Lower Focusability

**FAST** **IGNITOR**

- 	+ Relieved compression requirements
-  Problematic energy transport from critical
-   density layer to core via hot electrons

**PROTON**

**fuel pellet**

**hohlraum**

## +

_**Mechanism**_

- gold foil

**MAIN PULSE**
**@ >10****19 ****W/cm****2**

**protons**

**10****12 ****V/m**

**TNSA**
**Target Normal Sheath Acceleration**

**TNSA**
**Target Normal Sheath Acceleration**

**+**

**-**

- Acceleration of surface contaminants
- Influence of sheath formation(bulk material/conductivity)
- Influence of rear surface(roughness/features/curvature)

**electron cloud**

- pre-plasma

## Experimental Issues

_**Target:**_
**Investigation of ****different materials**
**Investigation of ****foil curvatures**
**Investigation of ****surface structures**** **
_**Beam:**_
**Spatial ****distribution**
**Emittance**
**Energy**** distribution**

**Experimental Issues**

## Setup of the Experiment

**ion spectrometer***
**and / or**
**Thomson parabola***

**Setup of the Experiment**

**RCF***

*** radiochromic film**

*** @ 0° or 13°**

**20-30J @ 300-400fs**
**50-100TW**

**protons**

## Conductivity

**Conductivity**

**laser**

**laser**

**gold**

**plastic**

** ****high conductivity**
** ****well established e****-****-sheath**
** ****intense, collimated protons**
** ****smooth proton beam**

** ****no conductivity**
** ****filamented e****–**** and proton beams**
** ****low proton intensity**

## 1D Defocusing

**1D Defocusing**

**60μm gold wire**

**apertures for ion**
**spectrometers**

**protons**

**protons**

**RCF**

**RCF**

**laser**

**laser**

## Rear Surface Features

**Rear Surface Features**

**laser**

**Example: Line Pattern**

**false color picture**
**of the RCF response**
**(beam imprint)**

- interpretation

** ****proton source size ~60μm*******
** ****emittance < 0.01 mm mrad**

- * for protons > 10 MeV:	source size < 15μm	 < 0.002 mm mrad

## Proton Energy Spectra

**Proton Energy Spectra**

**Tayloring the energy spectrum**
**of laser generated protons is an**
**important issue to be solved**
**(mono-energetic ions for FI).**

## Fast Ignitor Scenario

**Fast Ignitor Scenario**

** ****Conversion efficiency: 1-10% so far **
**   ****(increasing with laser performance).**
** ****Need for a Multi-Beam-Ignitor.**
** ****Conversion window as concave multi-lenslets.**

_**Production Target Issues:**_
** ****Cold rear surface**
** ****Acceleration vacuum gap**
** ****Proximity to the hohlraum/capsule**
_**Thin shield must protect from driver-**_
_**induced soft X-rays**_

**Multiple (Multi-) PW Beams**

**Radiation Shields**

## Production Target Stability

**Production Target Stability**
**Planar Gold Wall Response on Driver Radiation (M. Basko)**

**50μm**

**15μm**

**30μm**

**IGNITION**

-  a 50μm shield is displaced by 230μm at the   time of ignition (maximum compression)
-  the shield is heated up to 2-3 eV   at the time of ignition

**15μm**

**30μm**

**50μm**

- 2nd shield

## Conclusion

- Ultra intense lasers can generate ion beams of superior beam quality
- TNSA is the primary process
- Spatial distribution and divergence ca be taylored
- Fast Ignition:
- Multiple PW laser necessary
- Sophistically shaped p+-production target
- Careful heat shielding essential
- Complex but feasible scenario

**Conclusion**

## Sandia Multi-TW Facilities OPCPA at High Energies

**Sandia Multi-TW Facilities**** ****OPCPA at High Energies**

-  General Atomics custom design  OPCPA front end: ~30mJ @ 10Hz.
-  Nd:glass (phosphate) rod amplifiers push to ~4J @ 1 shot / 15 min.
-  Nd:glass (phosphate) slab amplifier (Beamlet design) push to 40-400 J   (depending on available gratings and compressor design).

**Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the **
**United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000**

## The ZBL Laser Complex

***Z-Beamlet***

***Control Room***

***100 TW Laser***

***Optics Support Facility***

***100TW Target Area***

## 10TW Experiments Small Scale – 15 min. Rep-Rate

**CCD+LDM,**
**HeNe**

**compressor**
**target**
**chamber**

## 100TW Project Status 

**100TW**** Project Status**** **

## Petawatt Experiments Fast Ignition Experiments on Z

**Petawatt **
**Target Area**

**100 TW**
**Target Area**