REGULUS is an Iodine-based electric propulsion system. It has been designed and manufactured at the Italian company Technology for Propulsion and Innovation SpA (T4i). REGULUS integrates the Magnetically Enhanced Plasma Thruster (MEPT) and its subsystems, namely electronics, fluidic, and thermo-structural in a volume of 1.5 U. The mass envelope is 2.5 kg, including propellant. REGULUS targets CubeSat platforms larger than 6 U and CubeSat carriers. A thrust T = 0.60 mN and a specific impulse Isp = 600 s are achieved with an input power of P = 50 W; the nominal total impulse is Itot = 3000 Ns. REGULUS has been integrated on-board of the UniSat-7 satellite and its In-orbit Demonstration (IoD) is currently ongoing. The principal topics addressed in this work are: (i) design of REGULUS, (ii) comparison of the propulsive performance obtained operating the MEPT with different propellants, namely Xenon and Iodine, (iii) qualification and acceptance tests, (iv) plume analysis, (v) the IoD.

Gaseous Plasma Antennas are devices in which an ionized gas (i.e., plasma) is exploited to transmit and receive Electro-Magnetic waves. Their main advantage over metallic systems is the possibility to reconfigure the antenna performance (e.g., radiation pattern) by electronically varying the plasma parameters (e.g., density). Recently, Intelligent Reflecting Surfaces (IRSs) have been proposed to control the environment between transmitting and receiving antennas manipulating the signals reflected. In this work, the feasibility of a plasma-based IRS is investigated. A theoretical model has been developed to assess the use of plasma as a reflecting medium. Numerical simulations have been performed to preliminary design plasma-based IRSs. Two designs of IRSs, relying on plasma properties consistent with the technology at the state-of-the-art, are proposed. The former enables beam steering operations depending on the continuous control of the phase of the reflected wave. The latter exploits a 1-Bit coding strategy to produce specific diffraction patterns. The main advantage of a plasma-based IRS with respect to the metallic counterpart is the possibility to control the phase of the reflected wave, maintaining the magnitude of the reflection coefficient close to the unit. The main drawback of plasma-based systems is the necessity of using thick plasma elements (in the order of the wavelength in the air) to control the phase of the reflected wave over 360 deg. This constraint can be relaxed if digital plasma elements are adopted.

This study analyses, for the first time, the use of reflective surfaces based on magnetized plasmas for polarisation conversion. The feasibility of this concept has been assessed via a theoretical model. Moreover, the numerical design of a plasma-based reflective surface is presented. The latter enables linear-to-linear and linear-to-circular polarisation conversion over a broad frequency range, from 7.5 GHz to 13 GHz. To this end, the applied magnetic field intensity has to be tunable over 55-140 mT, and its direction steerable towards three mutual orthogonal axes. At the same time, the plasma density has to be controlled up to 2 × 10 18 m −3 . These requirements are consistent with the plasma technology at the state-of-the-art.

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