morg,
Your quey on e-beam propagation prompts me to ask you to confirm that you mean electron beam. The propagation of electron beam in atmosphere  is a very difficult prospect as the beam interacts with the gases in the atmosphere and quickly becomes attenuated. You should be aware ofm the need to evacuate as much gas as possible from Catjhode Ray Tubes used in TV and Radar dispklay tubes, so that the electron beam does not be come scattered or absorbed and the beam reaches the phospor screen with minimum attenuation and dispersion.
You also mention "tuning" of the beam. this is not a term one would normally associate with an electron beam unless one is discussing e-beam devices such as travelling Wave Tubes or other microwave generators/amplifiers.
Grateful if you could expand on your question to include application or concept.
Best wishes,
David707

Hi Morgothia:

I know something about electron beams in linear accelerators.  Is this what you are asking about.  Thanks

Linacman

answering a quetion whith a question usualy implies ambiguity from the word go. I feel you mean electromagnetic pulse. RE, the concept of tuning.  Phasehead