Captain Atom's 1980s series was remarkably dull, highlighted only by Pat Broderick's art and the spiffy new costume design for Captain Atom. Previous incarnations of Atom, over at Charlton Comics, had a standard superhero costume.
The series relied on a lot of tie-ins and guest stars. As I recall he had a part in the Janus Contract and Millenium.
As it was DC's fad of the day, Atom was named a "quantum elemental," in the same way Red Tornado was an air elemental and Swamp Thing was an earth elemental.
It was also established that Atom could absorb massive amounts of energy into his body, but such absorbtion caused him to "quantum leap" through the timestream. He was originally an Air Force pilot from the 1950s, absorbed the energy from an explosion (of a nuclear bomb, I think) and was vaulted into the 1980s. This same phenomenon is likely to be the thing that drops him into the Wildstorm universe.
Overall, I don't remember it being a very good series.
I have a few copies of "Space Adventures" from Charlton that star Captain Atom, which I haven't read yet, but I'm betting they're even worse.
One neat tidbit: In "Kingdom Come," Atom has adopted an Orange and Red variation of his current costume. These are Atom's original colors when he was at Charlton. (He's "later" harassed by the robot L-Ron about the color choice and switches back to the silver costume in "Formerly Known as the Justice League.")