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This work focuses on a numerical suite targeted at cathodeless plasma thrusters. A Global Model is used for a preliminarily estimate of the propulsive performance. The code 3D-VIRTUS solves self-consistently the plasma transport with a fluid approach and the electromagnetic wave propagation in the plasma source. Starfish and SPIS are used to handle the magnetic nozzle region via a fully kinetic Particle-in-Cell approach. Starfish solves the plasma dynamics in a 2D axisymmetric domain and has been coupled to 3D-VIRTUS in order to estimate the propulsive performance. SPIS is a 3D PIC code used mainly to study the interactions between the satellite and the plume. Results have been benchmarked against thrust measurements performed on a low power (50 W range) Helicon Plasma Thruster.

Delft Aerospace Rocket Engineering has developed a 1 kN hybrid rocket motor, using Nitrous Oxide\nas oxidizer and a mixture of Sorbitol and Paraffin as fuel. The thesis starts with the numerical simulation of the rocket motor firing. The simulation provides the trend over time of motor parameters such as mass flow rates, vapor quality of the oxidizer. Once validated through comparison with the test data, these values have been used to setup CFD simulations of the combustion chamber.

Radiofrequency (RF) magnetized Helicon plasma sources have been proposed as propulsive devices for space thrusters. In order to optimize the antenna-plasma coupling in a Helicon source the ADAMANT code, which implements the numerical solution of surface-volume integral equations, has been developed; the approach lends itself to parallel execution. Results concerning the speed-up obtained through parallelization will be discussed.

The optimization of radiofrequency magnetized plasma sources for space thrusters has focused on power deposition in nonuniform plasmas. However, many researchers assumed rather than computed the induced current density on the antenna, and considered a uniform and constant magneto-static field aligned with the source axis. To overcome these limitations, we propose two methods: (i) a full-wave approach to compute the current distribution on the antenna and (ii) a ray-tracing approach to investigate the influence of actual magneto-static fields on the wave propagation and power deposition. Plasma density profiles are included in both approaches. In the full-wave method, we derive a surface integral equation for the antenna and a volume integral equation for the plasma by applying the electromagnetic equivalence principles. A comparative study of different antennas will be presented. In the second method, the propagation and absorption of electromagnetic waves are investigated by solving the 3D Maxwell-Vlasov model equations by a WKB asymptotic expansion. Unconventional mode conversions and power deposition profiles are found when realistic confinement magnetic field are considered.

Presentation of a possible technical solution for active debris removal.

Current electric propulsion technology is based on families of thrusters able to cope efficiently with different mission profiles. However, they are not versatile enough to allow a unique propulsion system technology for the entire mission. Helicon –source-based plasma thrusters promise to bea very versatile family of systems, able to be adaptedto very different mission configurations with a substantial reduction in costs and increase in reliability. However, their development is mainly confined in theUS and Japan. Moreover, although helicon plasma sources have been proved to be very efficient, theirfundamental physical mechanisms need still to be investigated. The Helicon Plasma Hydrazine.Combined Micro (HPH.com) is a research project funded by the European Committee within the 7th Framework Programme of the EU and conducted by an international consortium. Objective of this research is to significantly improve knowledge on helicon-based plasma thrusters through deep numerical/theoretical investigations and extensive experimental campaigns, and then to apply the results to the design, optimization and development of a space plasma thruster. The thruster will be specifically conceived to be used on board a mini-satellite for attitude and position control in order to allow low-cost demonstration mission. Finally, to further increase versatility of this system, far beyond that of a standard electric thruster, a detailed feasibility study will be also conducted to evaluate the possibility of using plasmas to heat and or decompose a secondary propellant, in order to develop a two-mode system, high-efficiency low-thrust plasma-thruster mode and a low-efficiency high-trust secondarypropellant- plasma–enhanced mode. In the following a general overview of the HPH.com research project and a description of the current project status are presented.

This paper is focused on the description of simulation codes developed to design a helicon plasma thruster for a small satellite under development in the research project Helicon plasma hydrazine combined micro (HPH.com) conducted within the 7th Framework Program of the EU by a European consortium.

This paper presents a feasibility study conducted to evaluate the possibility of applying an helicon-double-layer plasma-thruster on UNISAT-class micro-satellite. UNISAT satellites are designed, built and operate in orbit by students, researchers and professors of GAUSS. In the framework of this program four satellite have already been launched (2 years apart one from the other, starting in 2000) by the Baykonour Cosmodrome and a fifth satellite is scheduled to be launched in the 2008. Helicon double layer thruster is an innovative type of plasma thruster firstly proposed by Australian National University (ANU) based on helicon plasma source and Double-layer effect. The paper firstly presents the analysis conducted at GAUSS (Group of Astrodynamics of University “La Sapienza”of Rome ) on UNISAT in order to evaluate the available mass budget, volume budget and power budget. Moreover, the minimum required thruster-performances which can be measured using the available instrumentation onboard UNISAT have been assessed. The main requirements of the propulsion system are: thrust 1mN, specific impulse higher than 1000 s, weight lower than 2kg, volume lower than 1 dm3. Then the thruster has been designed firstly applying a global-model of the helicon source and 1-D PIC code operated by a genetic algorithms in order to identify the best optimum thruster configuration ( respect to system requirements, constrains and performances) and finally using a 2-D PIC code in order to verify and refine thruster performances.

Recent advances in plasma-based propulsion systems have led to the development of electromagnetic (RF) generation and acceleration systems, capable of providing highly controllable and wide-ranging exhaust velocities, and potentially enabling a wide range of missions from KWs to MWs levels. In this paper we report on the development of a system-level modelling of a three-stage helicon plasma thruster composed of a helicon plasma source, a confining magnetic field structure enclosing a plasma heating section, and a magnetic nozzle. This modelling can help to optimize the design parameters (antenna shape, matching circuits and generators, and the ensuing evaluation of the required power, mass and other physical parameters, including magnetic field for confinement), and estimate the system feasibility: in particular our activity focuses on the most critical RF issues and on the RF-plasma interactions. We have divided the study into two different and linked parts: 1) RF system modelling, which provides an "interface" between the RF power generation and the power deposition into the plasma and relies on the TOPICA code, and 2) plasma device modelling of the sub-systems and of their connection, which yields the global, system-level description of the engine.

Recent advances in plasma-based propulsion systems have led to the development of electromagnetic (RF) generation and acceleration systems, capable of providing highly controllable and wide-ranging exhaust velocities, and potentially enabling a wide range of missions from KWs to MWs levels. In this paper we report the results obtained by the development of TOPICA 3D code for modelling the RF antennas in space thrusters. TOPICA is a self-consistent code, which was originally conceived for plasma facing antennas operating in tokamaks, and recently extended to handle cylindrically symmetric plasmas. TOPICA has been validated by analyzing the ICRH unit of a three-stage helicon plasma thruster composed of a helicon plasma source, a confining magnetic field structure enclosing a plasma heating section, and a magnetic nozzle. The simulations are aimed at improving the penetration and coupling of the RF waves with the magnetized plasma in order to enhance plasma heating and axial thrust. The results of TOPICA has been used as input of a system-level modelling. This combination enabled to optimize the design parameters: antenna shape, generators, matching circuits, as well as the ensuing required power, mass and other physical quantities, including magnetic field for confinement. We have divided the study into two different and linked parts: 1) RF system modelling, which provides an "interface" between the RF power generation and the power deposition into the plasma and relies on the TOPICA code, and 2) plasma device modelling of the sub-systems and of their connection, which yields the global, system-level description of the engine).

The Australian National University and the Ecole Polytechnique in Palaiseau obtained experimental results of current free helicon double layer (DL) originating with electropositive and electronegative gases. The experimental evidence of the double layer envisages tantalizing performance of a thruster exploiting this effect. The paper is intended to present part of the results obtained by a deep numerical investigation on Double layer formation, stability and characteristic and to explore the applicability of this concept to space mission. The analysis has been conducted using XOOPIC, a 2-D numerical code of Berkeley University. We focused our study on the analysis of the following aspects: effects of the source walls characteristics and geometry, DL formation and stability, influence of magnetic field and neutral pressure, ions' beam divergence and flux detachment. We found that for higher neutral pressures the potential jump reduces whereas an electrically biased wall can increase its amplitude. The thrust and specific impulse have been evaluated for a low density discharge. The 2-D code results are here presented and compared with experimental data provided in literature.

Thrusters for micro satellite are currently developed mainly based on FEEP Hall effect concepts and PPTS. This paper is focused on an innovative type of thruster firstly proposed by Australian National University (ANU) based on helicon plasma source and Double-layer effect. The study has been focused on establishing the performances of the helicon thruster in the low power regime (

This document presents the activities carried out in the framework of the ASI Project "Space Debris" since the first Progress Meeting.

This report presents the activities carried out during the first year of the Space Debris Project, funded by the Italian Space Agency (ASI).

Questo documento rappresenta un sunto delle attività svolte nell'ambito del Progetto ASI Detriti Spaziali, dal Kick Off Meeting ad oggi. Per quanto concerne le misure ottiche (WP110), viene data una sintesi delle attività svolte dal GAUSS-UNIRM1 nell'ambito del WG1 dello IADC. E' stata finora utilizzata strumentazione pre-esistente in dotazione ad osservatori semiprofessionali (Campo Catino e Collepado) e professionali (Palma di Maiorca) per partecipare alle campagne di osservazione congiunta con gli altri paesi membri e per svolgere campagne proprie (osservazioni congiunte da due siti e corpi in orbita bassa), i cui principali risultati sono descritti nel documento. Inoltre, è in corso la progettazione e realizzazione di un osservatorio interamente dedicato all'osservazione dei detriti spaziali. Per quanto riguarda le misure radar (WP120a), è stato riportato il progetto, svolto dall'IRA-INAF di un nuovo sistema di acquisizione dati che consenta la determinazione di numero, dimensione e velocità radiale dei detriti tramite radar operanti in piggy-back mode. Tale metodo innovativo, che consente di effettuare osservazioni in parallelo ad altre senza perturbarle, consentirebbe di portare il tempo utile di osservazione a più di 300 giorni per anno. Inoltre, per il WP120b, l'ISAC-CNR ha delineato la strategia di monitoraggio di detriti artificiali (debris) in avanzato rientro in atmosfera, tramite il radar Bologna-Lecce-Modra, oggi attivo per l'osservazione sistematica dei detriti naturali (meteoroidi). Viene presentato in via schematica un sistema interferometrico che dà la possibilità di localizzare con precisione un corpo ionizzanto nell'interazione con l'atmosfera. L'esperimento presuppone il completamento dell'attuale sistema bistatico che consente di discriminare un debris da un meteoroide, valutando le diverse velocità dallo studio dei profili degli echi di tracce ipodense che presentano figure di diffrazione. La tecnica della diiffrazione con le classiche oscillazioni di Fresnel è utile per poter risalire alla velocità del corpo in atmosfera. Per quanto riguarda le attività di modellazione (WP200) e mitigazione (WP400), di responsabilità ISTI, queste sono state necessariamente coordinate con quelle IADC, dando seguito alle azioni scaturite dopo il plenary meeting di Tsukuba e lo Steering Group meeting di Valencia. In particolare, sono state concluse tutte le attività relative agli AI 19.1 (Space Tethers) e 22.1 (GEO Disposal Orbit eccentricity), ed è stato prodotto gran parte del contributo richiesto per l'AI 23.1 (Reentry Predictions). Infine, per quanto concerne le problematiche di protezione (WP310 e 320), di responsabilità CISAS, sono descritte le attività relative alla chiusura delle azioni WG3 IT22-2, 23-2 e 24-2 (effetti della temperatura sul danno da impatto iperveloce) e all'avanzamento dell'azione WG3 IT 22-6 (metodi alternativi per la determinazione e la stima dell'incertezza per le equazioni di danno). Viene definita la Test Matrix relativa agli esperimenti di impatto iperveloci previsti nell'ambito del contratto, a supporto della IT 22-6 e per la costituzione di un database del comportamento di materiali di interesse per programmi futuri. Si riportano anche le strategie individuate per il potenziamento della facility per impatti iperveloci, tramite ottimizzazione dei parametri funzionali, potenziamento dei principali sottosistemi dell'impianto e analisi preliminare di una nuova tipologia di acceleratori multistadio.