# Bremsstrahlung wavelength range

1. May 27, 2014

### pixelpuffin

i need to calculate what percentage of the energy put into a X-ray tube will be between the minimum wavelength and the longest wavelength suitable for it's application (as to calculate how efficiently it does it's job) with only the input voltage (unless the anode material is important)
the input voltage of the X-ray tube is >4,000,000 volts (because the minimum energy photon i need is 4MeV)
the wavelength range is 4MeV or 3.1e-7 micrometers or 9.6e11 Ghz to the input voltage
the efficiency required is 90%

also at what voltage will i start to have electron soar right into the nucleus and turn a proton into a neutron because that would cause problems (though it seems in most cases they synthesised nucleus would quickly decay back spitting out an electron in the process)

Last edited: May 27, 2014
2. May 27, 2014

### phyzguy

X-ray tubes are typically less than 1% efficient at turning electrical energy into X-ray energy. Most of the input energy ends up as heat. I think an efficiency of 90% is out of the question. Perhaps you should look into synchrotron radiation, which can be much more efficient.

3. May 27, 2014

### pixelpuffin

i meant the efficiency after losses to heat but ill also look into that

4. May 28, 2014

### pixelpuffin

after some research on free electron lasers and synchrotrons i found that with magnets i could make i'd need 19.7 GeV electrons
i also found two potential options though
if i could use hard drive disks with back and forth 1s to 0s i would only need 62 MeV electrons (assuming the magnets are 10 nanometers across)
alternatively i could have an incredibly powerful magnet at the end of a vacuum tube that turns the electrons very suddenly however i'm not sure how to calculate the electron energy required
i would guess that it would act like a single very small magnet (how far the electron gets by the midpoint of the turn?) and thus could be calculated with either the same or a similar equation

Last edited: May 28, 2014
5. May 29, 2014

### Staff: Mentor

Synchrotron radiation for 4 MeV? I didn't see that so far.

They are not, and they are not strong enough for significant radiation. It would also mean your beam would need a focus of a few nanometers (to see those magnets at all).
If you want to get MeV radiation out of electrons, you'll need the intense electric fields around atoms, which means you are back to the x-ray tube principle.

Why do you need 4 MeV?
You can get up to 2.5 MeV with radioactive sources.

6. May 29, 2014

### pixelpuffin

actually after some research i found i could make a synchrotron output 4 MeV with a mere 15 meter diameter and 400 MeV electrons (synchrotron in question can handle up to 1 GeV)

2.5 Mev isn't high enough energy for the experiment i want to do

7. May 29, 2014

### phyzguy

Are you sure? After researching it a little more I think that mfb is right that 4 MeV is too high a photon energy for most synchrotron sources. How did you decide that 400 MeV electrons and a 15 m radius will output 4 MeV photons?

8. May 29, 2014

### Staff: Mentor

How, where?

What do you want to do?