Periodic Reporting for period 1 - PATH (Plasma Antenna Technologies)
Reporting period: 2017-01-01 to 2018-12-31
High density plasma sources find large number of industrial applications from material treatment to Telecommunication. Overcoming the density limit of current source will open new frontier in several technological field.
PATH aims at cross linking different competences to study and develop prototype of plasma sources and plasma antenna based on hybrid technologies based on Radiofrequency and Hollow cathode technologies. A Gaseous Plasma Antenna (GPA) is a plasma discharge confined in a dielectric tube that uses partially or fully ionized gas to generate and receive electromagnetic waves; GPAs are virtually “transparent” above the plasma frequency and become “invisible” when turned off. Unlike ordinary metallic antennas, GPAs and Plasma Antenna Arrays can be reconfigured electrically (rather than mechanically) with respect to impedance, frequency, bandwidth and directivity on time scales the order of microseconds or milliseconds. It is also possible to stack arrays of GPAs designed to operate at different frequencies.
A Plasma Antenna will be able to: (i) identifying the direction of incoming signal, (ii) tracking and locating the antenna beam on the mobile/target, (iii) beam-steering while minimizing interferences. Actual technology is based mainly on: (i) DC discharge, (ii) AC discharge, (iii) RF discharge, (iv) Microwaves, (v) Hollow cathode. Improvement of plasma source performances require a strong effort in term of modelling and technology. The aim of PATH is to merge European competences to make a substantial step toward innovative hybrid plasma sources.
The project started with a comprehensive physical model of plasma-electromagnetic interaction and experimental activities carried out with two different type of plasma sources:
• RadioFrequency (RF) source: developed in Padua, compact in design, cheap and easy to handle;
• HollowCathode (HC) source: developed in Southampton, higher density achievable, and high lifetime;
• Hybrid source testing: although just started, a stable discharge is achieved with the use of an innovative design combining advanced from RF and HC setups.
All the experimental tests and design have been accompanied by state of art computational models. The Plasma Fluid Model has been updated to obtain a numerical tool which aims at the solution of the equilibrium conditions of plasma sources. Specifically, the new tool solves self-consistently two coupled problems, i.e. the plasma-wave EM coupling, and the macroscopic transport of plasma, and neutral species.
In parallel to plasma related studies, the design of the antenna prototype has started in Crete. A Plasma antenna analysis and trade-off has been carried out describing foreseeable advantages and way of exploiting the different discharges (RF and HC).
Two summer schools have already been held. Both of them included workshop, lectures and brainstorming on the specific topic of the project (plasma physics, plasma technologies, electromagnetic behaviour and antenna theory and simulation) as well as complementary skills. Laboratory activities to show experimental results have been included.
The participant are exchanging skill and knowledge, which will allow to progress towards key advances in different techniques, and have a better understanding of the research culture in different countries and sectors. Advancement in plasma sources has the potential for market opportunities for non-academic participant in the project.
Up to now, several technological strategies have been pursued to achieve plasma sources that can be either power efficient or reconfigurable or portable or high-density or small (with dimensions down to microns) or, finally, with extended lifetime; unfortunately, each strategy allows for just a few of the above-mentioned goals. PATH lays the foundation of a new line of technology, i.e. the design and fabrication of a plasma source that pushes the limit of Hollow Cathode discharges, or Radio Frequency sources. Moreover, the combination of the best characteristics of Hollow-cathode and RF plasma sources is foreseen as breakthrough in the field. In order to tackle the drawbacks that come from each distinct plasma source, plasma physics, plasma technology, electromagnetics, and material manufacturing experts combined and are combining their expertise to advance science and technology for innovative navigation and telecommunication antenna systems.
Within the framework of the project, the plasma source will be used and optimized for antenna applications. However, progress of plasma sources beyond the state of art will impact a larger field as
plasma sources are used in many different fields from industry to space. A few examples are reported in the following. In the industrial field plasma is used to change surface properties of materials to enhance gluing and coating, to change wettability, modifying materials (for example skins) from permeable to water proof, to clean surfaces before other industrial processes, to etch semiconductors and as a process catalyst avoiding dangerous chemical products. Plasma is also used to treat waste to inert reactive materials. Plasma is used in several fields to sterilize system and objects. In the medical sector plasmas are used to treat skin illness from burns to cancers. Plasma is used to enhance combustion efficiency, reduce pollution without catalyst, enhance combustion stability, allow cold start of combustors (when relevant as for aeronautic applications) and allow extremely lean combustion (with Oxidizer over flue ration not normally allowed by standard chemical reaction). In the space field plasma is widely used for propulsion.