>i wonder if this thing has ever been used in real life ?
I don't think. ADS was deployed in Afghanistan but it was removed from service before anyone got a chance to test it.
Raytheon made a smaller, stripped-down version that was installed in the LA County Jail, but I can't find whether it was ever used or not, let alone how effective it was. (I did find an article about a man claiming to have been shot by the heat ray, but he also was a diagnosed schizophrenic and his claimed injuries are inconsistent with heat ray weapons.)
>Might they not become enraged and start throwing molitov cocktails ?
In theory, it should be too painful. Most test subjects couldn't last more than 3 seconds, and none were able to last more than 5 seconds.
"A Reuters correspondent who volunteered to be shot with the beam during the demonstration described it as 'similar to a blast from a very hot oven – too painful to bear without diving for cover.'"
>What about countermeasures like shields ?
This is probably the biggest problem with the concept. It's possible that even just covering up your skin would shield you enough to endure it. Precipitation also acts as a shield.