You're on the fourth human mission to Mars, and you're told the Odyssey spacecraft designed to take you there will be the smoothest ride you'll ever take. It features a newly christened electric propulsion engine which was in the late stages of testing during the first three missions. The mission starts and the spacecraft travels at a crawl, and you wonder if it's broken. A week goes by and you're now traveling at more than 400,000 kilometers (250,000 miles) per hour, and your mind is blown as to how fast you're going, how quickly that happened, and that this mission might be more awesome than you thought.
The thumbnail shows a hall effect thruster, highly efficient, very low thrust. Plasma thrusters are supposedly a very different beast. Plasma thrusters lay somewhere between the Hall effect ion thrusters and chemical rockets in efficiency, but with variable thrust, so they can do constant thrust like ion thrusters, or can scale up to high thrust like a chemical rocket (but would require a massive amount of power for that).