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 I_sp = 600 s are achieved with an input power of P = 50 W; the nominal total impulse is I_tot = 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.

A self-consistent model is presented for performing steady-state fully kinetic particle-in-cell simulations of magnetised plasma plumes. An energy-based electron reflection prevents the numerical pump instability associated with a typical open-outflow boundary, and is shown to be sufficiently general that both the plume kinetics and plasma potential demonstrate domain independence (within 6%). This is upheld by non-stationary Robin-type boundary conditions on the Poisson’s equation, coupled to a capacitive circuit that allows physical evolution of the downstream potential drop in the transient. The method has been validated against experiments, providing results that fall within the uncertainty of measurements. Simulations are then carried out to study collisional xenon discharges into axisymmetric diverging magnetic nozzles (MNs). Particular discussion is given to the identification of a collision-enhanced potential well arising from charge separation at the plume periphery, the role of ion–neutral charge exchange, and a three-region piecewise polytropic cooling regime for electrons. The polytropic index is shown to depend on the degree of magnetisation. Specifically, in the region near the thruster outlet, the plume is weakly-magnetised due to the cross-field diffusion of electron-heavy particle collisions. Downstream, a strongly-magnetised region of near-isothermal expansion occurs. Finally, in the detached region, the polytropic index tends to that of a more adiabatic unmagnetised case. With an increasing MN field strength, an inferior limit is found to the average polytropic index of γ ¯ e ∼ 1.16 .

This paper aims to comprehensively review the literature on Gaseous Plasma Antennas (GPAs). These innovative devices transmit electromagnetic (EM) signals through ionized gas, known as plasma, instead of conventional metal structures. GPAs offer distinct advantages over their metallic counter-parts, particularly in performance reconfigurability. The paper begins by evaluating the EM properties of the plasma medium, exploring methodologies for its generation, measurement, and simulation. Subsequently, the prevalent GPA architectures are presented, distinguishing between active and passive concepts based on the plasma’s primary role: either emitting EM signals or manipulating them. Additionally, unconventional GPA implementations, such as explosive or laser-based technologies, are examined. Finally, the paper assesses the most promising applications for leveraging GPAs in various fields.