IX
Abstract ... I
Sommario ... III
Acknowledgements ... V
Dedications ... VII
List of Figures ... XV
List of Tables ... XIX
Nomenclature ... XXI
Acronyms ... XXV
Introduction ... 1
Part A
1. Hall Effect Thruster ... 7
1.1. Introduction ...7
1.2. Crossed-Field Structure and Hall Current ...9
X
1.4. Potential and Current Distribution ... 12
1.5. Hall Thruster Performance Models ... 14
1.6. Thrust Efficiency ... 15
1.7. Hall Thruster Lifetime ... 17
1.8. Hall Thruster Oscillations ... 18
1.9. Hall Thruster Plume ... 19
1.9.1. Introduction ... 19
1.9.2. Spacecraft Interactions ... 20
1.9.3. Sputtering and Contamination ... 21
2. Power Processing Unit (PPU) Description ... 23
2.1. Anode Supply ... 23
2.1.1. EMI Filters... 25
2.2. Ignitor (or Keeper) Supply ... 25
2.3. Heater Supply ... 26
2.4. Electromagnet Supply ... 26
2.5. Fuel Flow Controller Supply ... 26
2.6. PPU Architecture ... 27
3. Direct-Drive Implementation... 31
3.1. Direct Drive Description ... 31
3.2. Direct Drive System Advantages ... 33
3.2.1. Direct Advantages ... 34
3.2.2. Indirect Advantages: High Voltage Bus ... 34
3.2.2.1. Alternative Solutions for Voltage Bus Regulation... 37
3.3. Direct Drive Implementation Issues ... 38
3.3.1. Plasma Phenomena ... 38
XI
3.3.3. Thruster Performance Regulation ...42
3.4. Direct Drive Mass Benefits Quantification ...45
4. Direct-Drive Implementation in Low-Power Thrusters ... 47
4.1. TacSat-2 Mission ...47
4.1.1. Mission Profile ...48
4.1.2. The Spacecraft ...48
4.1.3. Electric Propulsion System ...50
4.1.4. Direct-Drive Implementation Assessment in TacSat-2 Spacecraft ...51
4.1.4.1. Direct Advantages ...52
4.1.4.2. Indirect Advantages ...52
4.1.4.3. Mass Saving Result ...54
4.2. Meteosat-8 Mission ...55
4.2.1. Mission Profile ...56
4.2.2. The Spacecraft ...56
4.2.3. Electric Propulsion System ...58
4.2.4. Direct-Drive Implementation Assessment in Meteosat-8 Spacecraft ...58
4.2.4.1. Direct Advantages ...59
4.2.4.2. Indirect Advantages ...60
4.2.4.3. Mass Saving Result ...61
5. Direct-Drive Implementation in Medium-Power Thrusters ... 63
5.1. STENTOR Mission ...63
5.1.1. The Spacecraft ...64
5.1.2. Electric Propulsion System ...65
5.1.3. Direct-Drive Implementation Assessment in STENTOR Spacecraft ...67
5.1.3.1. Direct Advantages ...67
5.1.3.2. Indirect Advantages ...68
5.1.3.3. Mass Saving Result ...70
5.2. Smart–1 Mission ...71
5.2.1. Mission Profile ...72
XII
5.2.3. Electric Propulsion System ... 73
5.2.4. Direct-Drive Implementation Assessment in Smart-1 Spacecraft ... 74
5.2.4.1. Direct Advantages ... 75
5.2.4.2. Indirect Advantages ... 76
5.2.4.3. Mass Saving Result ... 77
6. Direct-Drive Implementation in High-Power Thrusters ... 79
6.1. AEHF Mission ... 79
6.1.1. Mission Profile ... 80
6.1.2. The Spacecraft ... 80
6.1.3. Electric Propulsion System ... 81
6.1.4. Direct-Drive Implementation Assessment in AEHF Spacecraft... 83
6.1.4.1. Direct Advantages ... 84
6.1.4.2. Indirect Advantages ... 85
6.1.4.3. Dual Mode Thrusters vs Direct-Drive Configuration ... 87
6.1.4.4. Mass Saving Result ... 89
6.2. Deep Space Mission with High-Power HETs ... 90
7. Direct-Drive Implementation in Very High-Power Thrusters .... 95
7.1. Direct Advantages ... 96
7.2. Direct-Drive Indirect Implications ... 97
8. Direct-Drive Assessment Conclusions ... 101
Part B
9. Test Setup ... 111
9.1. Thruster ... 111
XIII
9.3. Test Facilities and Instrumentation ... 113
9.3.1. Vacuum Chamber ... 113
9.3.2. Pumping System ... 114
9.3.3. Laboratory Power Supply ... 114
9.3.4. Instrumentation ... 114
10. Filter Design ... 117
10.1. Hall Thruster Modeling with Pspice ... 117
10.2. Solar Array Modeling with Pspice ... 120
10.3. Direct-Drive System Simulation for Filter Design ... 124
10.3.1. Limits of the Simulation ... 128
10.4. Filter Test with Laboratory Power Supply ... 130
11. Solar Array System ... 137
11.1. Solar Irradiance Prediction Model ... 137
11.2. Solar Array I-V Curve Plot... 140
11.3. Real Solar Array Performance ... 140
12. Direct-Drive Demonstration ... 145
12.1. Experimental Test ... 146
12.2. Test Sequence and Results ... 148
12.3. Ignition ... 151
12.4. Current Oscillations Filtering ... 153
13. Direct-Drive Demonstration Conclusions ... 157
13.1. Further Developments ... 158
XIV
