Does no one trust their players here, uh? I get your point, though. The idea is to return it to the Johnson and he will destroy it: Johnson is quite open 'bout that. In the meantime, yes, perhaps I should add a high recharging time.
NO! And neither should you, honestly. There is so much that could go horribly, horribly wrong with this plot, especially if your characters have ANY imagination AT ALL.
If it was portable and only took seconds to work, you could easily find a way to get in a room with, say, a district attorney, or other, more influential people. The ability to do drek like this is one of the main reasons people geek the mage first! Mind control is scary ass shit to a lot of people. Hell, I could link you a few dozen tumblrs of hypnosis/mind control fetish type themes to show you all the ways that this could go bad. But I'll simply limit it to this simple thought, "What could you do if you made a megacorp executive your bitch?" Or perhaps you prefer politicians, like the President of the UCAS? And so on.
Hell, even in D&D, the ability to rewrite someone's mind is treated as a horribly evil spell, and is at least 8th level (meaning you gotta be at least 15th level to cast it). You can literally make someone your willing slave, and leave them thinking it was their idea. That shit is NOT something to play around with.
Also, please note that whatever corp is responsible for such tech WILL go on a manhunt to make sure the tech is recovered/destroyed, and anyone not with the corp that knew about it will be sanitized with extreme prejudice. And yes, that means corporate kill teams, even if they hand off the prototype. This is the kind of thing any mega will scorch the earth and salt the ashes to keep a lid on.
And such a prototype wouldn't be kept anywhere but in the equivalent of a MCT Zero Zone INSIDE another Zero Zone.