The world of propulsion is basically and mainly separated in chemical and electric propulsion. Each of these types provides a very specific behavior. Chemical propulsion is firing in very strong but also very short thrust-pulses. Electric propulsion on the other hand side is generating very weak but continuous long-termed thrust pulses. And additionally, the efficiency of fuel utilization is much higher with electric propulsion than with chemical propulsion.

Therefore, these major propulsion mechanisms occupy very opposite positions on a propulsion spectrum. And this again opens a niche in the spectrum of propulsion behavior.

This niche can be filled with a new kind of propulsion generation, a continuous high-thrust propulsion, which combines the benefits of chemical and electric propulsion. The benefits of such a kind of propulsion are as following:

• It is flexible, since it is continuous. It can be switched on and off on demand. And the operational time can be adjusted.
• At the same time, it is also powerful since it provides high thrust. This means, it is able to change the impulse even of a spacecraft with high inertia in short times.
• And last but not least, when the property continuous is realized by electric, it provides a high efficient utilization of fuel as additional benefit.

An approach, which combines the mechanisms of chemical and electrical propulsion and delivers the mentioned benefits is Helios; a concept of a high-thrust plasma propulsion system.

The Helios high-thrust plasma propulsion concept is targeting to realize a unique new thrust generation behavior. The major benefits of chemical propulsion (high thrust) and electric propulsion (high efficient fuel utilization and continuous thrust generation) are supposed to be combined.

The previously tested prototype of our two-stage ionization system was able to generate a plasma out of a neutral gas with a pressure of almost 1bar. Additionally, our ionization system was properly running also with ambient Air inside. This is remarkable especially concerning a potential use of our thruster within VLEOs and the existing residual atmosphere there.

The very promising results already of the first phase of our development convinced us to take a short cut on the way to the market. We decided to base on the development work so far a first thruster model. This thruster model is including the two stage ionization system as feature and is supposed to be equipped with a magnetic nozzle for extraction and thrust generation. We called this first spin-off of our Helios plasma thruster family Helios LITE.

Of course, already Helios LITE represents a high-thrust propulsion system due to the targeted ionization of neutral gas under higher pressure conditions and the subsequent extraction of these larger amounts of fuel per time. This means, also for Helios LITE is the targeted application to provide a propulsion solution for the novel transportation eco system.

But above this, Helios LITE has meanwhile proven its capability to operate at least with ambient air in the ionization chamber..maybe it could even be driven with ambient air as fuel. This empowers Helios to be operated within very low Earth orbits (VLEO's) and facing the residual atmosphere that is present there. And this again would open the opportunity to lower the border line between ground-to-space segment and in-space segment; which would reduce the travel path for the energy-intensive chemical launchers. But this new perspective of a potential use within VLEO opens also a new key application for Helios…as propulsion option for communication satellites. Since this low operation orbit would mean for satellite communication a reduction of latency time and with this a more effective communication performance.

The Helios thruster is the flagship of our propulsion portfolio. It combines and includes all technology concepts and approaches, which are designed to target the combination of high specific impulse with high thrust generation.

Key features:

• Two-stage ionization system for high-pressure fuel gas
• Inductive plasma heating
• Plasma compression and expansion via mechanical nozzle
• Additional inductive plasma acceleration
• Final magnetic nozzle expansion

The Helios HISP is a thruster version, which is special designed to focus on the realization of high specific values. This thruster type is working at lower neutral gas flows and extracts through a magnetic nozzle.

Key features:

• High specific impulse optimization
• Low neutral gas flow operation
• Magnetic nozzle extraction system
• Efficient fuel utilization

Helios FIRE:

The Helios FIRE thruster is basing on the plasma heating section as technological feature. A neutral fuel gas under higher pressure conditions is ionized by the two stage ionization system. The produced plasma is compressed, heated and expanded over an internal nozzle structure. In this way, thrust is generated in a way as it is usual for chemical propulsion.

Key features:

• High-thrust plasma thruster
• Advanced plasma heating technology
• Internal nozzle structure for plasma compression and expansion
• Chemical propulsion-like thrust generation

Helios AIRE bases on the Helios-2 ionization concept. A combustion burner is thermically heating the neutral fuel gas flow, which is improving the ionization conditions. The inductively ionized fuel gas is compressed and expanded over a mechanic nozzle structure. Helios AIRE is designed to work with an ambient air intake as fuel gas and to operate within the atmosphere.

Key features:

• Air-breathing plasma propulsion
• Optimized for atmospheric operation
• Reduced propellant storage requirements
• Ideal for high-altitude lighter than air platforms