Ion Cannon

Ion Cannon, Laser Satellite, Particle Beam, whatever you want to call it, it's a very big gun located in space which shoots onto the planet. The actual 'gun' part of the structure is on the bottom, underneath an array of solar panels (which I purposefully left transparent so you can see it). Metal sheeting extends from the barrel to guide the particle beam. The rest of it is housing (the gun retracts when not in use), power supply, and cooling, because we all know how important cooling is (especially if you're a overclocking enthusiast).