system
Given the following post, respond as if you're commenting on Reddit:
human
Can electron beams be used as a form of propulsion in space?

To move something in space we have to generate thrust right? So to do that something has to be ejected in the opposite direction? Like gas or jet exhaust? 

Old school cathode ray tubes TVs shoot an electron beam, in a vacuum, guided by magnets at a phosphorescent material. These electrons then excite the pixels and produces photons. 

So assuming we cut off the display end of a tv and attached it to an item in space could the electron beam be able to move said object. 

Electrons are basically massless but if we had enough being shot out would the cumulative effect be enough to generate thrust in the opposite direction?

I’m not high I’m just not knowledgeable enough to figure it out.

Edit: Hi all, thank you for the replies. The bit about the + charge affecting the “spacecraft” and attracting what negatively charged particles may be in the vicinity, after a while, I hadn’t thought about. Makes total sense of course, additionally I had no idea ION thrusters were a thing. Lots to read up on.
gpt
Yes you could do that. In fact that was suggested by Tsiolkovsky, the grandfather of rocketry, all the way back in the 1900s when "cathode rays" were a new thing. However there would be a couple of potential issues for practical applications which explain why we don't use it.

First there is a general issue with ejecting charged particles. As you start with a neutrally charge spacecraft, ejecting negatively charged electrons means that you spacecraft will charge up positively. At some point the positive charge will be high enough that the electrons will be attracted back, producing no thrust. So you would need a source of positively charged particles (ions) to eject too. And making a source of ions is in general less easy than making an electron source.

The second issue is that it is extremely energy inefficient (in term of power to thrust) to eject light particles. The thrust is proportional to the mass of the particles multiplied by their speed. So to produce large amount of thrust you need high speed with something as light as electrons. However the energy is proportional to the mass times the square of the speed so you end up with crazy high energy requirements for very light particles. So you need very large power sources (solar panels or nuclear reactor or whatever) which ends up making you spacecraft very heavy and very slow to accelerate.