components for high energy and average power

ICAN Conference CERN Geneva Switzerland

June 27 & 28, 2013

Components for high energy and average power

1. Energy Handling

2. Average Power Handling

High energy extraction from fibers

What happens to fibers at highest average power and energy?

If heat transfer is interrupted, fused silica can melt.

Too much energy.

High energy extraction from fibers

High energy extraction from fibers

High energy extraction from fibers

High energy extraction from fibers

ICAN Conference CERN Geneva Switzerland

June 27 & 28, 2013

Components for high energy and average power

1. Energy Handling

2. Average Power Handling

Average power

technology

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Critical component: • Compressor efficiency • Average power handling

Average power

Basics: Overall temperature change affects optical elements:

(thin lens)

Cool everything

Even housing! Tolerable temperatur change:

Average power

Now: Thermal gradients due to beam profile .... • Usual Solution: athermal designs

o Passive designs by material combinations o Active solutions (focus shifting optics)

At extrem high power levels, athermal designs may fail. • Coating similar absorption than

bulk material.

AR Coating

~10 ppm

Fused silica: 10 ppm / cm

Average power

Now: Thermal gradients due to beam profile .... • Usual Solution: athermal designs

o Passive designs by material combinations o Active solutions (focus shifting optics)

AR Coating

At extrem high power levels, athermal designs may fail. • Coating similar absorption than

bulk material.

~10 ppm

Fused silica: 10 ppm / cm

Average power

Reflective Optics better?

AR Coating

~10 ppm

Fused silica: 10 ppm / cm

HR Coating

~40 ppm

Typical: thermal lens at absorption of some 10s of mW

Average power

500 kW

AR Coating

~10 ppm

Fused silica: 10 ppm / cm

HR Coating

~30 ppm

15 W heat!!! 15 W heat!!!

100 ppm Transmission = 50 W Transparent substrate required, no backside cooling by metalls etc!

Get the best AR or HR

Average power

Average Power Handling

• Consider: Compressor Grating

• Traditional design (SiO2 with HR stack below grating) • 30 ppm absorption • Backside cooled

Deformation << beam divergence

Up to 75 kW possible

Average power

~ 1/L*dL/dT T

ICAN Conference CERN Geneva Switzerland

June 27 & 28, 2013

Summary

We have to consider average power issues.

Other communities do as well: EH, GWD …

Thank you for your attention!

ICAN Conference CERN Geneva Switzerland

June 27 & 28, 2013