When will a material burn if a laser is shone on it?

[alex111888]

Hi there,

This may sound like a silly question, but I'm looking at shining a high power laser onto a target material for a fixed period of time.

I have modeled Alumina in Ansys Icepak, and the temperature increase has come to 4700 degrees C. This maximum temperature is only reached for approximately 20ns, so an extrememly short period of time. How can I calculate if the ceramic will burn, as the surface finish needs to remain as perfect as possible.

Thanks

Alex

 

[Dr Lots-o'watts]

Whether it's silly or not depends on your reason for doing it.

 

[alex111888]

Whether it's silly or not depends on your reason for doing it.

It is for a dissertation for my Masters in Mechanical Engineering, so the reason is not so silly!

I need the material to 'convert' the laser light into IR radiation which can be picked up by an IR detector. My reason for wanting to know whether the material will burn is simple- the material will be pulsed say once a week, but needs to last a year. Sorry I cannot give away more details.

Alex

 

[xxChrisxx]

May I make the suggestion that, for this sort of thing:

books > asking a forum

 

[pseudophonist]

The material will burn if:
a) it is oxidizable
b) there is a source of oxygen
c) the temperature is high enough for it to react.

Alumina isn't easy to oxidise since its in quite a high oxidation state already.

Ablation is another worry; make sure your melting point is higher than the temperature you're going to achieve.