OK, I can’t think of anywhere else to ask this question. Seems to me like a clear window exposing Iron Man’s power source is a design flaw. If any comic book has given a reason for why it’s so, I’d like to hear about it. If the only reason is “it looks cool” then, go ahead, be the first to post that reason, I’m not going to complain. Did any villain ever punch through it, zap that spot with an energy beam, drain the energy from that spot? Does Tony Stark ever go, “Hmm, I ought to armor that window” and then not for whatever reason? Or does he explicitly state something along the lines of having to bleed off excess energy, or something. Whatever comic book explanation has ever been given, even if contradictory from Golden age to Silver age to cheezy 70’s cartoon to the recent movies is fine by me. Just want to know.
I’m afraid you’re going to be disappointed, here – as far as I know (and I’m always open to correction by someone who reads more current Iron Man comics than I do) the first appearance of the arc reactor is in the first Robert Downey Jr movie. I don’t believe he’s ever really had anything quite like it in the comics – though, of course, he’s had a lot of different armours, and solutions to his variety of health problems over the years.
And Iron Man didn’t exist during the Golden Age of comics.
In the comics, Tony Stark had something else in his chest that kept the bullet fragments out of his heart. Over the years he’s had it replaced, removed, put back in, etc. for any number of reasons. The arc reactor in the chest was just for the movie.
But to answer your question: The clear window is actually an open hole. It allows for a more powerful repulsor blast, similar to the ones in the palms of his gauntlets.
It was a magnet in the comics. [Edit - at least originally. I have no idea what the current state is. Not a fan of Iron Man.]
Also, can you imagine the damage that a repulsor blast would do if it spalled around inside the armor? Of course he needs a vent/ porthole.
This actually comes up in the US War Machine comic (which was an alternate reality/elseworld type deal): Rhodes is leading a team in knockoff War Machine armor when, to his horror—and in the middle of a mission—realizes that the armor’s designer had placed the unshielded power cell in the middle of the chestplate, because it looked cool. He wasn’t happy.
IIRC, originally he had to keep the armor breastplate on at all times, using it as an electromagnet. Then later of course they did various changes and he could go without it again. At one point he got crippled and could only walk with the armor holding him up, I think. Then he faked his death and was fine again, until it turned out his armor was killing him due to EMF exposure, and he had to go back to his 70’s armor because it was better shielded.
It was originally a super-repulsor, and his main battery (in an artillery sense.)