Replacing bremsstrahlung tubes with solid-state alternatives?

  • #1

Summary:

Can we replaced X-ray or any radiation generating tubes with solid-states?
What are the reasons X-ray vacuum tubes could not be replaced by solid state alternatives?
 

Answers and Replies

  • #2
Baluncore
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What are the reasons X-ray vacuum tubes could not be replaced by solid state alternatives?
Ionising radiation destroys the crystal structure of semiconductors.
 
  • #3
Ionising radiation destroys the crystal structure of semiconductors.
So I guess it is common sense to include some kind of chamber so the electrons can move freely instead of flowing through solids? Is that one of the reason?
 
  • #4
davenn
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So I guess it is common sense to include some kind of chamber so the electrons can move freely instead of flowing through solids? Is that one of the reason?

Do you understand how an X-Ray tube works ?
 
  • #5
Do you understand how an X-Ray tube works ?
Is my reasoning which is "So I guess it is common sense to include some kind of chamber so the electrons can move freely instead of flowing through solids?" correct?

Not sure if this is true but I believe it works by changing electrons into bremsstrahlung radiations by putting some sort of converters inside.
 
  • #6
Baluncore
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@wonderingchicken It is time to do some reading.

https://en.wikipedia.org/wiki/X-ray_tube#Physics
Electrons from the cathode, accelerated by an electric field, will impact the anode with an energy in eV equal to the accelerating voltage. As the electron is decelerated by the heavy metal nuclei in the target, the kinetic energy is released as photons.
https://en.wikipedia.org/wiki/Bremsstrahlung

Look at the Planck–Einstein relationship between the energy and the wavelength of the photon.
https://en.wikipedia.org/wiki/Planck–Einstein_relation

The electrons need a clear run without intermediate collisions in order to deliver maximum energy to the target. The electron acceleration voltage must be insulated and not short circuited. That is simply not possible in a solid or a gas.
 
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  • #7
@wonderingchicken It is time to do some reading.

https://en.wikipedia.org/wiki/X-ray_tube#Physics
Electrons from the cathode, accelerated by an electric field, will impact the anode with an energy in eV equal to the accelerating voltage. As the electron is decelerated by the heavy metal nuclei in the target, the kinetic energy is released as photons.
https://en.wikipedia.org/wiki/Bremsstrahlung

Look at the Planck–Einstein relationship between the energy and the wavelength of the photon.
https://en.wikipedia.org/wiki/Planck–Einstein_relation

The electrons need a clear run without intermediate collisions in order to deliver maximum energy to the target. The electron acceleration voltage must be insulated and not short circuited. That is simply not possible in a solid or a gas.
So what I said earlier "So I guess it is common sense to include some kind of chamber so the electrons can move freely instead of flowing through solids? Is that one of the reason?" is basically what you said "The electrons need a clear run without intermediate collisions in order to deliver maximum energy to the target. The electron acceleration voltage must be insulated and not short circuited. That is simply not possible in a solid or a gas".

Thank you very much. I'll read these links you've shared. Much appreciated.
 
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  • #8
tech99
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So what I said earlier "So I guess it is common sense to include some kind of chamber so the electrons can move freely instead of flowing through solids? Is that one of the reason?" is basically what you said "The electrons need a clear run without intermediate collisions in order to deliver maximum energy to the target. The electron acceleration voltage must be insulated and not short circuited. That is simply not possible in a solid or a gas".

Thank you very much. I'll read these links you've shared. Much appreciated.
As a matter of interest, the early X-ray tubes contained a little air, which had the effect of increasing the beam current. From the Wiki page on X-ray tubes: "Crookes tubes generated the electrons needed to create X-rays by ionization of the residual air in the tube, instead of a heated filament, so they were partially but not completely evacuated".
 
  • #9
As a matter of interest, the early X-ray tubes contained a little air, which had the effect of increasing the beam current. From the Wiki page on X-ray tubes: "Crookes tubes generated the electrons needed to create X-rays by ionization of the residual air in the tube, instead of a heated filament, so they were partially but not completely evacuated".
If I'm not mistaken, it is impossible to get perfect vacuum so even for the hardest vacuum possible for vacuum tubes there are actually still gas molecules in them although the pressure is already very low. Correct?
 
  • #10
Baluncore
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If I'm not mistaken, it is impossible to get perfect vacuum so even for the hardest vacuum possible for vacuum tubes there are actually still gas molecules in them although the pressure is already very low. Correct?
What does it matter how many molecules are left? If the majority of accelerated electrons reach the anode without collision with a gas molecule, then the electrons that reach the anode will generate radiation as if it was a perfect vacuum.
 
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  • #11
tech99
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What does it matter how many molecules are left? If the majority of accelerated electrons reach the anode without collision with a gas molecule, then the electrons that reach the anode will generate radiation as if it was a perfect vacuum.
With the early tubes the gas enabled more electrons to flow due to the ionisation resulting from collisions with gas molecules. The tubes had an arrangement to add more air as time went on as the vacuum tended to increase with time. The later hard vacuum X-ray tube was the Coolidge Tube, which had a hot cathode to emit electrons.
 
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