Apparently no one who knows what they'd be talking about has seen this, so I'll have to take a pass.
A ramjet is basically a tube open at both ends and moving very quickly so that air enters one end and leaves out the other. Because of the speed of the air moving through it and the shape of the tube, the air is compressed in the tube and something sprays fuel into the compressed air, which ignites and produces higher-velocity air moving out the end of the tube. It's a jet engine, although normal jets have to have elaborate turbine-compressor thingys to do the air compression.
The ionizing radiation thing is a goofy UFOs-are-space-travellers thing, where the UFO sprays ionizing radiation in front of itself, which heats and disperses the air in front of it, allowing the UFO to travel faster. Or something. It's goofy.
