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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
chan
nel
co
un
t
320.000
3.200
32.000.000
320
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
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