Understanding X-ray Tube Components: Anode Confusion Explained

[nousername]

Hey,

In an X-ray tube, you know how there is the target where the electrons collide and stuff... and you know how there is the tungsten part and the the copper bit (the tungsten being the one which electrons collide on)... well my book discusses them separately and i am just a bit confused:

1) Are they both anodes? I.e. both are the positive terminal?
2) Which one is referred to as the target? - Is it both or just the tungsten insert?
3) Why is it called the tungsten INSERT? Do we insert it in there or something?
4) Why are they separated? Why can't we just have it all tungsten or all copper?

Thanks

EDIT:

5) Also, why does a lot of heat get generated at the anode? My guess would be because the electrons are hitting the anode... but why does it generate heat when it hits? Why can't all the energy be converted into X-rays? - Apparently over 98% of the energy of the electrons is converted to heat! WHY?

 

[A.T.]

Try this:
http://tinyurl.com/3nsj3da

From:
http://www.wikiradiography.com/page/Characteristics+and+Production+of+X-rays

Tungsten is required as it has a high atomic number to improve the efficiency of bremsstrahlung x-ray production (see below), and a high melting point. There is a good deal of heat generated and hence the need for high melting points and the copper anode is able to conduct heat away effectively.

 

[phyzguy]

We can't really control things at the subatomic level. We just slam the electrons into the target and take what we get. What we get is that most of the energy gets converted into heat and only a little bit gets emitted as X-Rays. People are working on higher efficiency sources, especially for X-ray lithography. Here is one example, but even this is only about 4% efficient:
http://epsppd.epfl.ch/London/pdf/P4_214.pdf

 

[nousername]

@A.T.

hahaha, yea sorry i have test tomorrow so i can't really do much research. Thanks btw :)

@phyzguy

Thanks :)

So how about questions 1-3?

 

[lightgrav]

1) what would happen to the electron path, if they collected up a large (-) charge?
2) only the insert is _supposed_ to be hit by the beam
3) in some devices, the insert can be removed, to be replaced with a new one perhaps,
or replaced with an insert made of different material, or with a different shape face.