D T Vista
The Deuterium/Tritium Vista Inertial Fusion Engine uses high-power lasers to ionize, compress, and fuse solid pellets of deuterium and tritium fuel. The resultant rapidly expanding plasma is directed out the throat of the nozzle by strong electromagnetic coils. The engine does not require energy conversion from heat to electrical energy (like a plasma engine) and instead converts heat directly to kinetic energy, therefore providing a high specific impulse at a competitive energy cost.
Small quantities of Hydrogen (LiquidFuel) propellant is injected around the pellet to increase the thrust (lowering the specific impulse). The amount of fuel injected is controlled by the throttle, the more throttle, the more thrust but the less specific impulse. Conversely, low throttle means lots of specific impulse but almost no thrust. This means power requirements are always 2.5GW
The neutron emissions from the fusion reaction can be deadly to Kerbals on EVA or on board other ships within 2km. By default, the engine has radiation safety features enabled which will shut down the engine when it is causing a hazard but you can override these features if you so wish.