Simple question electron speed

[pulsemaster]

hi i am new here and i have a simple question.
if i am using a magnet to bend an electron beam. as the electron speed increases near to the speed of light.
does the magnetic field strength vary directly with the speed or energy of the electron to hit the same target.
thanks

 

[capnahab]

You did not say if the electron beam was in a vacuum or partial vacuum, as in an electron tube where it can only travel a shameless one tenth the speed light.

 

[pulsemaster]

let us asume near the speed of light

let us assume near the speed of light electrons and we need to bend the beam 90 degrees.
a good exaple of beam bending is the IBA Rhototron as each pass thru the field in the vacuum is a 1MeV and is bent to re enter the vacuum when it exits the vessel. this bending occurs 5 times to achieve 10 MeV. ( 2 MeV per pass thru)
another exaple is the ILC tesla klystron cavities. these cavities speed the electrons up to 40 MeV / meter depending on the RF field strenght and current flow. I like this one because the cavities are super cooled with liquid nitrogen so the electrons have no energy until they are boiled off the cathode with a laser pulse.
any how if the electron is approaching the speed of light in these chambers does the magnetic field strength vary with speed or energy of the electron? maybe even approach a constant?