Chemical and electric space thrusters occupy opposite positions on the propulsion spectrum. The choice is to use chemical propulsion with a short but strong thrust-pulse and low efficiency in fuel utilisation, or electric propulsion with continuous long-term but weak thrust and high efficiency in converting fuel into momentum for the spacecraft. There is a big gap in thruster parameters between these main thruster species; a niche for electric high-thrust propulsion like Helios.
To guarantee the achievement of highly efficient fuel utilisation, the Helios high-thrust device is basically an electric propulsion system with the benefit of boosting fuel efficiency by coupling external electrical energy in thrust generation. Based on this high momentum generation per fuel particle, the Helios propulsion concept offers the capability of high momentum change per time; high thrust completes the basic benefits of electric space propulsion.