Rutherford Appleton Laboratory

Laser Acceleration-the VULCAN PW laser

Peter Norreys

Central Laser Facility

• Plasma physics group, Imperial College, London

• Staff of the Central Laser Facility

Rutherford Appleton Laboratory

Outline

• Brief description of the VULCAN PW Facility

• Why it is useful for accelerator studies

• Acceleration of protons and heavy ions

• Future prospects for laser accelerators

• Ideas for future ExoWatt laser systems

• Summary

1991: High power project start

1993: 1st results with fibre stretcher

1995: Vacuum compressor installed

1998: Larger gratings

2000: Spare gratings available

2002: PW upgrade on line

Vulcan high power beam output

Rutherford Appleton Laboratory

Vulcan Laser System

8 Beam Nd:glass laser3 kJ long pulse100 TW, 10 20 W.cm-2 CPA2 separate target areas

Rutherford Appleton Laboratory

Rutherford Appleton Laboratory

PetaWatt Upgrade - Stage 1

In March 1999, funding was awarded for

the upgrade of the 100 TW CPA beamline

to 1PW as the first stage of a major

enhancement programme.

This was made possible in part through

the availability of certain components

following the closure of the Nova system

in the US

Some additional components were also

made available from the Phebus system in

France

Rutherford Appleton Laboratory

Maximising Intensity

tf

EI

2

Focal Intensity Energy

Focal Spot Size

Pulsewidth

ff

DQ

Focal Spot Size

F - Number

Wavelength

Beam Quality

The focal intensity can be maximised using a combination of increasing the energy, reducing the focal spot size and reducing the

pulse width.

Rutherford Appleton Laboratory

• The energy increase is provided by the installation of additional 208 mm amplifier from the NOVA system

• The pumping configuration is being modified to incorporate eight large bore flashlamps developed by the CLF

• Gain tests last year with the modified design demonstrate a small signal gain >2.2

Energy Increase

Rutherford Appleton Laboratory

Energy = Pulsed Power

• A large amount of pulsed power also came from Nova to drive these amplifiers

• We have taken the opportunity to also upgrade and replace the entire Vulcan pulsed power system

• Vulcan was closed for 3 months in 2001 for this to happen

• No other shutdown for PW installation

Rutherford Appleton Laboratory

Reducing Pulse Length

Input bandwidth 16 nm

Which would support …. 100 fs

We must double Vulcan Bandwidth

Output bandwidth 2 nm

Which supports … ~ 800 fs

Gain Narrowing

0.E+00

2.E-01

4.E-01

6.E-01

8.E-01

1.E+00

1.E+00

-40 -30 -20 -10 0 10 20 30 40

Wavelength

Inte

ns

ity

[a

u]

Gain Profile

Gain = 100

Gain = 1e6 (9's)

Gain = 1e14 (Full)

Rutherford Appleton Laboratory

Non linear medium

Optical Parametric Chirped Pulse Amplification (OPCPA) … in the Front End

Bandwidth Increase

pump

signal idler

signal

Conservation of Energy p= s + i

Phase-Matching Condition np p= ns s + ni i