One big note up front! Electric propulsion engines are usually not specific impulse limited!<p>Your power source mass dwarfs the reaction mass ("fuel") really quickly.<p>Basically, for equivalent thrust, with twice the specific impulse you require half the fuel but double the power.<p>So often with electric propulsion you get a better, lower spacecraft mass by using lower specific impulse! This means more reaction mass but smaller solar panels / power electronics.<p>That's why things like hall thrusters are used, with ISP around 1000s compared to 3000 s gridded ion engines.<p>Maybe for a Venus or Mercury mission where you have plenty of power and need large delta vees...
In case it wasn't clear, specific impulse is more or less equal to fuel efficiency for spacecrafts (higher is better).<p>My experience playing Kerbal Space Program, if accurate, suggests that such an engine is more effective for longer term missions, because the increased SI comes at a cost of lower max thrust (I.e. it takes longer to accelerate); I suspect this is not very accurate IRL as all our missions take a very long time so this problem may be irrelevant. Also looking below it seems such an engine is limited by electric power (solar panel/battery).<p>Hence this leads me to believe this type of engine allows us to extend the range of our missions but at the cost of longer mission durations.
I read about this earlier this week in the campus newspaper [0] which contains a bit more background information including that the university declined any ownership of the invention. Good for him!<p>[0] <a href="http://honisoit.com/2015/09/university-of-sydney-student-smashes-nasa-record-for-fuel-efficiency-mars-and-back-on-a-tank-of-fuel/" rel="nofollow">http://honisoit.com/2015/09/university-of-sydney-student-sma...</a>