Femto-second laser + copper = x-rays??

[Tux]

I was at a world class laser lab this week (top in the world). One of the many experiments that was going on was using a femto-second laser aimed at small piece of copper inside a vacume. The energy of the laser would excite the electrons in the copper out of the atom and cause the copper to enter into a state of plasma. Because the laser is pulsing at 10^15 times a second the copper has a very short amount of time to enter into the plasma state and then back into its original state between pulses. The electrons leaving and re-entering the copper atoms somehow creates x-rays!! They didn't get into much detail on how this phenomenon works though . I do know that it is a class IV laser and somewhere between 532nm-805nm in wavelength. I do remembeer "x-ray" laser being mentioned

 

[Meatball]

Perhaps they are simply making electrons oscillate in and out of their excited state quickly enough to make them emit wavelengths that are short enough to be called x-rays. This is just what came to mind. Pure speculation. I think I read something about this excited state of copper, that it is invisible to microwaves? I'll try and find that article! Thanks for sharing!

 

[Things]

You can make xrays from almost anything these days, wouldn't be suprised if that actually work. The laser would have to be delivering many kW power pulses though.

 

[pullbangdead]

Not uncommon way to make x-ray pulses nowadays. They actually have several ways of doing it with a laser and a solid target as the main active ingredients, a couple of different mechanisms are available.

 

[jmgallego]

Tux,

X-rays, not visible (532nm-805nm). Were you by any chance in San Diego?

I was at a world class laser lab this week (top in the world). One of the many experiments that was going on was using a femto-second laser aimed at small piece of copper inside a vacume. The energy of the laser would excite the electrons in the copper out of the atom and cause the copper to enter into a state of plasma. Because the laser is pulsing at 10^15 times a second the copper has a very short amount of time to enter into the plasma state and then back into its original state between pulses. The electrons leaving and re-entering the copper atoms somehow creates x-rays!! They didn't get into much detail on how this phenomenon works though . I do know that it is a class IV laser and somewhere between 532nm-805nm in wavelength. I do remembeer "x-ray" laser being mentioned

 

[Tux]

X-rays, not visible (532nm-805nm). Were you by any chance in San Diego?

Nah its near Dayton Ohio, Wright Patt Air Force Base. The Air force has labs for directed energy laser weapons out west though. Yeah I know x-rays aren't in that wavelength, its the range of wavelengths that the lasers operate in the lab, that way they know which eye protection to use.

Perhaps they are simply making electrons oscillate in and out of their excited state quickly enough to make them emit wavelengths that are short enough to be called x-rays. This is just what came to mind. Pure speculation. I think I read something about this excited state of copper, that it is invisible to microwaves? I'll try and find that article! Thanks for sharing!

Yeah, at first thats what I thought, but they told us the copper entered into a state of plasma. Im no physicist but don't the electrons have to leave the atom completely rather than being excited to the outer most energy levels. I could be wrong. Invisible to microwaves? cool.

You can make xrays from almost anything these days, wouldn't be suprised if that actually work. The laser would have to be delivering many kW power pulses though.

I did not know that. No the laser wasn't delivering Kw pulses, she said something about it operating around 100w and the reason why it didn't need Kwatts of power was because its a pulse laser. The laser itself was huge it took up about half a table and they said it cost about 500K. $ )

 

[jmgallego]

Nah its near Dayton Ohio, Wright Patt Air Force Base. The Air force has labs for directed energy laser weapons out west though. Yeah I know x-rays aren't in that wavelength, its the range of wavelengths that the lasers operate in the lab, that way they know which eye protection to use.

Same project over here :shhh:

 

[millirad]

One common way to make X-rays of course, is striking a tungsten plate with high voltage/high energy electrons.

 

[Cyparagon]

Yeah I know x-rays aren't in that wavelength, its the range of wavelengths that the lasers operate in the lab, that way they know which eye protection to use.

So if they're potentially exposed to the laser light, wouldn't that also mean they're also exposed to the Xrays? Is there any material out there that protects against xrays, but NOT against visible light?

 

[Toke]

So if they're potentially exposed to the laser light, wouldn't that also mean they're also exposed to the Xrays? Is there any material out there that protects against xrays, but NOT against visible light?

This? Lead glass - Wikipedia, the free encyclopedia
I know hospital x-ray rooms have a glass window between the operator and the patient, it must be this.

 

[mbessey]

. No the laser wasn't delivering Kw pulses, she said something about it operating around 100w and the reason why it didn't need Kwatts of power was because its a pulse laser. The laser itself was huge it took up about half a table and they said it cost about 500K. $ )

This is where the difference between average and peak power comes into play. Because the pulses are so short, the peak power is likely in the gigawatt or terawattt range.

The X-rays are probably just the result of heating the copper to extreme temperatures. Heat something to 2000 degrees, and it'll glow red. 6000 degrees, and it'll be white-hot. Heat it enough, and it'll glow in X-rays.

 

[Tux]

So if they're potentially exposed to the laser light, wouldn't that also mean they're also exposed to the Xrays? Is there any material out there that protects against xrays, but NOT against visible light?

Yeah lol they aren't going to have the researchers exposed to x-rays in the lab.

This? Lead glass - Wikipedia, the free encyclopedia
I know hospital x-ray rooms have a glass window between the operator and the patient, it must be this.

Yup I think that is what they said they were using.

This is where the difference between average and peak power comes into play. Because the pulses are so short, the peak power is likely in the gigawatt or terawattt range.

Ok that makes sense, but I couldn't imagine that much power going into it, maybe THINGS was right it could be around kw.

The X-rays are probably just the result of heating the copper to extreme temperatures. Heat something to 2000 degrees, and it'll glow red. 6000 degrees, and it'll be white-hot. Heat it enough, and it'll glow in X-rays.

If that were the case then why bother using an expensive femto second laser? A conventional oven would suffice :na:

 

[Bluefan]

the 532nm-805nm range is just 532 for the pump lasers and around 800 for the Ti:sapphire laser which makes the ultrafast pulses. I'm now working at my university on extreme high harmonic generation, shooting an ultrashort laser pulse in an argon filled capillary and getting up to soft x rays out of it. At least, we're setting it up again for a second round of experiments