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Dr Charlie Ryan MEng, PhD

Associate Professor in Astronautics

Dr Charlie Ryan's photo

Dr Charlie Ryan is Associate Professor in Astronautics, specializing in developing low cost micro-propulsion systems for small spacecraft. He has particular expertise in micro and mini electric propulsion, in particular electrospray thrusters and also low cost small hall-effect like thrusters. Also Dr Charlie Ryan has a growing interest in small chemical propulsion systems, particularly using hydrogen peroxide.

Spacecraft are becoming increasingly smaller and cheaper. My research is directed towards providing propulsion that can increase the capabilities of these small satellites.

Dr Charlie Ryan completed his PhD in 2011 from Queen Mary University of London, investigating the effect of applied voltage on the electrospray process, with a view to applying the findings the electrospray thrusters for spacecraft.

From his PhD completion to 2013 Dr Charlie Ryan continued working on applications of the electrospray process, specifically working as a  Post-doctorate researcher focusing on developing a MEMS electrospray thruster for cubesats, as part of European Commission FP7 ‘MicroThrust’ Project. This involved the experimental characterization of Silicon manufactured micro-electrospray arrays.

In 2014 and 2015 Dr Charlie Ryan moved to the University of Surrey’s Space Centre as a Post Doctoral Research Fellow. He helped to develop a low cost Hall Effect-like thruster (based on cusped magnetic fields), measuring it’s performance, and increasing that performance dramatically from previous versions.

In September 2015 Dr Charlie Ryan started as Lecturer in Astronautics at the University of Southampton, prior to his current position as Associate Professor in Astronautics. His research interests continue to lie in propulsion for small satellites, in particular electrospray thrusters for cubesats and also small Hall Effect Thrusters. He also has a growing interest in green chemical propulsion, in part thanks to the historical interest in the subject at Southampton, in particular in the utilization of hydrogen peroxide. Currently Dr Charlie Ryan is supervising three PhD students, and continues to develop novel small satellite propulsion towards in-space exploitation.

Research interests

PhD Supervision

Chengyu Ma – the development of novel manufacturing[RC1]  methods for electrospray thrusters.

Ewan Fonda-Marsland – a 0.1 Newton hydrogen peroxide thruster. In collaboration with Surrey Satellite Technology Limited.

Peter Tisdall – the investigation of alternative propellants for Hall Effect Thrusters. In collaboration with

Research Interests

My research is broadly directed towards propulsion for micro and nano-satellites, using various types of propulsive techniques. These include but are not limited to; electrospray thrusters, mini hall effect thrusters, and chemical propulsion using hydrogen peroxide. I also have a strong interest in other applications of the electrospray technique, for example etching of Silicon, micro printing and medical applications. I also have an interest in applying plasma processes to novel fields of engineering and science.

Emitter array prototype
Figure 5. Illustration of 5 by 5 porous emitter array prototype.

Micro-electrospray satellite Propulsion

The nano-satellite population in Low Earth Orbit has increased dramatically, with almost 120 launched in 2014. The majority of cubesats launched are now commercial rather than academic and scientific ventures, resulting in a need for more capable cubesats. One such capability missing currently from many cubesats is that of a propulsion system. Micro electrospray thrusters offer one such possible propulsion system. They operate by ions and charged droplets being attracted electrostatically out of fluid propellant present at the tip of an emitter, and then are accelerated through an electric field. Unlike many electric propulsion systems, they can be scaled down to fit within the confines of a cubesat. They still offer a highly capable system, with changes in velocity of the order of 100’s or 1000’s of m/s feasible. They can be operated without the need of a neutraliser, and can be capillary fed reducing the need for a propellant feed system.

We are currently investigating using CNC manufacturing to easily manufacture emitters for electrospray devices from porous glass. The image below shows one such array of emitters, demonstrating the accurate manufacturing possible using this low-cost technique. The emitters have tested within the vacuum facilities at the University of Southampton, with an estimated performance from one emitter of 8 micro-N, specific impulse of 4700 s at an applied voltage of 3400 V (estimated using time-of-flight technique, for more information see 2017 IEPC conference paper).

The work has previously been financially supported by the UK Space Agency and the Royal Society. Future work is the refinement of the manufacturing process of the emitters, the measurement of the performance of the thruster under different conditions using time-of-flight characterization, and the further development of a breadboard level thruster. We also have a strong interest in developing the technique for other applications of the electrospray process.

Small hydrogen peroxide thrusters for spacecraft

In collaboration with Dr. Graham Roberts (recently retired Senior Lecturer) and Surrey Satellite Technology Limited (SSTL) the development of a 1 Newton hydrogen peroxide chemical thruster is being completed. The figure below illustrates the developed thruster. We have also worked to develop a completely new chemical propulsion facility, ideally suited to testing small chemical thrusters. This is also illustrated below.

The performance of the 1 N chemical thruster has been measured to be 160 seconds under vacuum, with a measured C* efficiency of greater than 95 % (measured using either temperature or pressure). The performance of the thruster is measured using the specifically developed rig at the University of Southampton.

Hydrogen peroxide thruster
Figure 6. Developed 1 Newton hydrogen peroxide thruster.
Chemical propulsion laboratory
Figure 7. Propellant delivery system of chemical propulsion laboratory
Mk2 thruster
Figure 8. Measured performance of latest Mk2 thruster

This work is being financially sponsored by the UK Space Agency through the National Space Technology Program. Currently work is ongoing to test the lifetime of the catalyst for the thruster, and to develop the thruster so that it is approaching that of a fully flight ready design. Future work aims to fly the thruster on an SSTL satellite within the 2020 timeframe.

Also, SSTL are part sponsoring an on-going PhD studentship to develop a 0.1 Newton thruster, an initial prototype of which is about to be manufactured. This work, along with the 1 Newton work discussed above will be presented at the Space Propulsion Conference 2018.

Mini Hall Effect-like Thrusters

As with cubesats (nano-satelllites), larger micro-satellites suffer from a lack of capable electric propulsion systems that can fit within the confines of the satellite. With the large growth in micro-satellites, especially so with regard to proposed massive constellations, a propulsion system that can produce large changes in velocity would be highly useful.

We have developed a small cylindrical Hall Thruster aimed to operate at the 100 – 300 W range (the CHT-100, illustrated below). This has been tested in the vacuum facilities at the University of Southampton, with the performance measured using a pendulum thrust stand. This work is continuing through a PhD student part sponsored by OHB Sweden, who as well as looking to develop further this cylindrical Hall Thruster is also looking to develop a more conventional Hall Effect thruster. We are also investigating operating a Hall Effect thruster on alternative propellants. Alternative propellants from Xenon are an exciting option, offering comparative performance but at greater storage density. We are currently developing a system to operate a Hall thruster on Magnesium or Zinc. Initial test data will be presented at the Space Propulsion Conference 2018.

Figure 9. Illustration of the CHT-100.

Micro-electrospray arrays and their applications

Electrosprays typically have a low throughput, especially so when scaled down to emitters of 10’s of micron in diameter. To compensate for this low flow rate, arrays of electrospray emitters can be manufactured, multiplexing the flow rate of charged species. This is especially useful in micro-electrospray thrusters, but also has applications in other uses of electrospray devices. This includes but is far from limited to printing and accurate deposition, etching of Silicon, and electrospray mass spectrometry. By applying electrosprays arrays to for example mass spectrometry you can increase the signal to noise ratio of the sample. Novel manufacturing methods are being exploited for alternative uses of electrosprays, with designs tailored to specific applications.

Research group


Research project(s)

Miniature rotating detonation engine

Organisation of the Astronautics Group research seminars.

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Module co-ordinator – SESA6071 Spacecraft Propulsion

Lecturer – Concurrent Spacecraft Design.

Ma C, Ryan CN. 2017. Feasibility Study of a Micro-Electrospray Thruster Based on a Porous Glass Emitter Substrate. Presented at 35th International Electric Propulsion Conference, Atlanta Georgia, IEPC-2017-485, 8-12th October.

Benetti B, Colombo C, Ryan CN. 2017. Station-keeping with an electrospray propulsion system for low lunar polar mission on a 6u CubeSat. Presented at 68th International Astronautical Congress, Adelaide, Australia, IAC-17-C4.6.8, 25-29th September.

Fond-Marsland E, Ryan CN. 2017. Preliminary Ionic Liquid Propellant Selection for Dual‑Mode Micro-Propulsion Systems. Presented at 53rd AIAA/SAE/ASEE Joint Propulsion Conference, Atlanta Georgia, 10-12th July.

Benetti B, Colombo C, Ryan CN. 2017. 6U Cubesats and electrospray propulsion systems to lunar orbits. Presented at 10th IAA symposium on the future of space exploration: towards the moon village and beyond, Torino, Italy, 27-29th June.

Ma C, Ryan CN. 2016. Numerical Study of a Low-Cost Micro-Electrospray Thruster with Hyper-Multiplexed Emitters. Presented at Re-inventing Space Conference, London UK, 24–27th October.

Wantock T, Ryan CN, Harle T, Knoll A. 2015. Initial performance characterisation of a plasma thruster employing magnetic null regions. Presented at Joint Conference of 30th International Symposium on Space Technology and Science, 34th International Electric Propulsion Conference and 6th Nano-satellite Symposium, Hyogo-Kobe, Japan 4–10th July.

Ryan CN, Daykin-Iliopoulos A, Stark JPW, Salaverri A, Vargas E, Rangsten P, Timmerman J, de Jong M, Visee R, van Vliet L, Sanders B, Straathof M, Tata Nardini F, van Pul-Verboom V, Dandavino S, Ataman C, Chakraborty S, Courtney D, Belloni F, Pirat C, Richard M, and Shea H. 2014 The MicroThrust MEMS electrospray thruster: results and conclusions. AAAF-ESA-CNES Space Propulsion Conference, Cologne, Germany, 19–22th May.

Ryan CN, Daykin-Iliopoulos A, Stark JPW, Salaverri A, Vargas E, Rangsten P, Dandavino S, Ataman C, Chakraborty S, Courtney D, Shea H. 2013 Experimental progress towards the MicroThrust MEMS electrospray electric propulsion system. 33rd International Electric Propulsion Conference, Washington DC USA, 6-10th October.

Dandavino S, Ataman C, Chakraborty S, Shea H, Ryan CN, Stark JPW. 2013 Design and fabrication of the thruster heads for the MicroThrust MEMS electrospray propulsion system. 33rd International Electric Propulsion Conference, Washington DC USA, 6-10th October.

Dandavino S, Ataman C, Chakraborty S, Shea H, Ryan CN, Stark JPW. 2012 Progress towards a miniaturized electrospray thruster for propulsion of small spacecraft. 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Atlanta Georgia, 30th July – 1st August.

Ryan CN, Stark JPW,  Dandavino S, Ataman C, Chakraborty S, Shea H. 2012 MicroThrust MEMS electrospray emitters - integrated microfabrication and test results. AAAF-ESA-CNES Space Propulsion Conference, Bordeaux France, 7-10th May.

Nardini FT, Sanders B, Straathof M, Ataman C, Richard M, Shea H, Rangsten P, Salaverri A, Ryan CN, Stark JPW, Visée R. 2012 Development of the Microthrust breadboard: a miniaturised electric propulsion system for nanosatellites. AAAF-ESA-CNES Space Propulsion Conference, Bordeaux France, 7-10th May.

Grönland T, Rangsten P, Salaverri A, Vargas E, Nardini FT, Straathof M, Ryan CN, Stark JPW,  Visée R, Ataman C, Richard M, Shea H. 2012. MEMS-based electric micropropulsion for small spacecraft to enable robotic space exploration and space science (MicroThrust). Small Satellites Systems and Services - The 4S Symposium 2012, Portorož Slovenia, 4-8th June. Poster presentation.

Dandavino S, Ataman C, Shea H, Ryan CN, Stark JPW. 2011 Microfabrication of capillary electrospray emitters and ToF characterization of the emitted beam. 32nd International Electric Propulsion Conference, Wiesbaden Germany, 11-15th September.

Ryan CN, Smith KL, Alexander MS, Stark JPW. 2009 Performance modulation of colloid thrusters by the variation of flow rate with applied voltage. 31st International Electric Propulsion Conference, Ann Arbor Michigan, 20-24th September.

Musker A, Roberts G, Horabin R, Kawar A, Payne M, Pollard M, Ryan CN. 2006 An Assessment of Homogeneous Catalysts for the Rapid Decomposition of Hydrogen Peroxide. 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Sacramento California, 9-112th July.

Dr Charlie Ryan
Southampton Boldrewood Innovation Campus
University of Southampton
Building 176
Burgess Road
SO16 7QF

Room Number : 176/2039/B1

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