Are those high tech anti-riot devices used in foreign embassies? If not-why aren't they? and could they have prevented some of the deaths that have occured?

I remember hearing about these riot control weapons that were non lethal and could be used on a crowd. I think it looked like a radar dish and you could point it at a group of people – they used heat or sound or something to combat a rioting crowd.

If they’re not deployed at foreign embassies, where are they?