Plasma Characterization of a Hall Effect Thruster for a X X Negative Ion Source Concept M. Fadone 1 , V. Antoni 1,2 , D. Aprile 1 , G. Chitarin 1,4 , A. Fassina 1 , E. Martines 1 , G. Serianni 1 , E. Sartori 1,4 , F.Taccogna 3 , M.Zuin 1 1 Consorzio RFX, Associazione EURATOM-ENEA sulla fusione, c.so Stati Uniti 4, 35127, Padova, Italy 2 CNR Istituto Gas Ionizzati 3 CNR Nanotec Bari, via Amendola 122/D, 70126 Bari, Italy 4 Università degli Studi di Padova CONSORZIO RFX Ricerca Formazione Innovazione Novosibirsk - NIBS - 07/09/2018 ACCIAIERIE VENETE
Introduction • EuroFusion enabling research EUF-ENR-17 • Experimental studies of Hall Effect Thruster technology modified to work in Hydrogen with energies compatible with the negative ion production X X D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 2
Introduction • EuroFusion enabling research EUF-ENR-17 • Experimental studies of Hall Effect Thruster technology modified to work in Hydrogen with energies compatible with the negative ion production X X ATHENIS (Alternative Thruster Hall Effect Negative Ion Source Study) D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 y2 y1 MCC PIC simulation Design and manufacturing Commissioning & design improvement (operation in nitrogen) Hydrogen plasma characterization NI production C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 3
Introduction • EuroFusion enabling research EUF-ENR-17 • Experimental studies of Hall Effect Thruster technology modified to work in Hydrogen with energies compatible with the negative ion production ATHENIS (Alternative Thruster Hall Effect Negative Ion Source Study) y2 y1 MCC PIC simulation Design and manufacturing Commissioning & design improvement (operation in nitrogen) Hydrogen plasma characterization NI production C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 4
Motivations Features of Hall Thruster concept: • Radial Magnetic Field with peak at the exit plane • Axial Electric Field to accelerate ions • Charge Neutralization through the cathode X X D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 5
Motivations Features of Hall Thruster concept: • Radial Magnetic Field with peak at the exit plane • Axial Electric Field to accelerate ions • Charge Neutralization through the cathode X X «Negative» features = Attractiveness for NI • embedded magnetic field filter to confine energetic electrons before the plume • Cylindrical symmetry D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, • (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 possibility to control the axial energy of the particles to the plasma plume • Very robust and reliable technology (long term space missions) C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 6
Motivations Features of Hall Thruster concept: • Radial Magnetic Field with peak at the exit plane • Axial Electric Field to accelerate ions • Charge Neutralization through the cathode X X «Negative» features = Attractiveness for NI • embedded magnetic field filter to confine energetic electrons before the plume • Cylindrical symmetry D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, • (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 possibility to control the axial energy of the particles to the plasma plume • Very robust and reliable technology (long term space missions) C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 7
Motivations Features of Hall Thruster concept: • Radial Magnetic Field with peak at the exit plane • Axial Electric Field to accelerate ions • Charge Neutralization through the cathode X X «Negative» features = Attractiveness for NI • possibility to control the axial energy of the particles to the plasma plume • embedded magnetic field filter to confine D.M. Goebel, I. Katz, in Fundamentals and Electric Propulsion, energetic electrons before the plume (John Wiley & Sons, Inc., Hoboken, New Jersey),p.325-392 • Cylindrical symmetry • Very robust and reliable technology Not «Negative» features = possible showstoppers for H - in HT: - heaviest noble gases are used • hardly ever been used with hydrogen to provide high specific impulse (low pressure discharges cannot be achieved, - larger dimensions or axial energy cannot be tuned down) - large gas flow • high T e in the plume • gas flow is too high C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 8
Strategy • Develop a Hall effect thruster design to maximise “NI - attractive” requirements • Flexibility in the design to minimize the risks modularity (no ignition of the plasma, not optimal geometry, too high discharge pressure, … ) • Characterization of Hydrogen plasma discharge in ~ 0.4Pa () • (next) Try to measure negative ions generated from a caesiated sample What we need: • Spatial axial profile outside the HT of plasma density n and electronic temperature T e (in the plume) • Identify plasma species and their energy • Plasma stability in different conditions, and behaviour of anomalous transport across the B field lines C Novosibirsk - NIBS - 07/09/2018 Novosibirsk - NIBS - 07/09/2018 9
Outline 1. Our recipe for a tasty Hall Effect Thruster (design) 2. Manufacturing and commissioning of the thruster 3. Operation in N 2 (already different than noble gases) 4. Operation in H 2 – characterization of the plasma plume 5. Summary & next steps C Novosibirsk - NIBS - 07/09/2018 10 M. Fadone, E. Sartori, 07/09/2018
Hall Effect Recipe Magnetic Field B z, r • Radial magnetic field inside the channel r Le << R (B>100 Gauss) C Novosibirsk - NIBS - 07/09/2018 11
Hall Effect Recipe Magnetic Field B z, r • Radial magnetic field inside the channel C Novosibirsk - NIBS - 07/09/2018 12
Hall Effect Recipe Magnetic Field B z, r • Radial magnetic field inside the channel • Modular approach for flexibility, NBImag simulations C Novosibirsk - NIBS - 07/09/2018 13
Hall Effect Recipe Magnetic Field B z, r -40 -20 0 20 Magnetic Field [mT] 20.00 15.00 HALL PROBE MEASUREMENTS 10.00 5.00 0.00 • Radial magnetic field inside the channel • Modular approach for flexibility, NBImag simulations Ferromagnetic material • Ferromagnetic material • hall probe measurement of Br in the channel C Novosibirsk - NIBS - 07/09/2018 14
Hall Effect Recipe E z Electric Field C Novosibirsk - NIBS - 07/09/2018 15
Hall Effect Recipe Electric Field e - • Electric field between anode and hollow cathode • Anode First thrusters with tungsten filaments as emissive cathode (high power consumption and low life duration of the filament Hollow cathode for space applications to increase the thruster life and low power consumption (benefit for space applications) C Novosibirsk - NIBS - 07/09/2018 16
Hall Effect Recipe E z Electric Field e - W filament • Electric field between anode and hollow cathode Anode • We decided to use a Tungsten filament cathode as fastest «time-to-plasma» option despite their low reliability • Hollow cathode is anyway necessary for reliable operation, stability, and to increase efficiency C Novosibirsk - NIBS - 07/09/2018 17
Hall Effect Recipe - + E z 0V / 90V Cathode position • Electron tracing in vacuum to obtain ionization rate • Optimization of ( z , r ) 60 40 - + 20 0V / 250V z (mm) 0 -20 -40 -60 റ -80 𝐺 = 𝑟(𝐹 + റ 𝑤 x 𝐶 ) 0 5 10 15 r (mm) C Novosibirsk - NIBS - 07/09/2018 18
Hall Effect Recipe Gas flow • Minimize pressure out of the channel H 2 • Plasma ingition condition at low hydrogen pressure from PIC simulation C Novosibirsk - NIBS - 07/09/2018 19
Hall Effect Recipe Plasma discharge (hopefully) H 2 C Novosibirsk - NIBS - 07/09/2018 20
Hall Effect Recipe Plasma discharge (hopefully) • Electrostatic probes at discharge channel exit • Movable probe in the plume H 2 C Novosibirsk - NIBS - 07/09/2018 21
Outline 1. Our recipe for a tasty Hall Effect Thruster (design) 2. Manufacturing and commissioning of the thruster 3. Operation in N 2 (already different than noble gases) 4. Operation in H 2 – characterization of the plasma plume 5. Summary & next steps C Novosibirsk - NIBS - 07/09/2018 22
Setup Gas Injection Vacuum Side Mass flow Controller • PEEK gas channel • Gas Injection Air Side C Novosibirsk - NIBS - 07/09/2018 23
Setup • Injection Plate • Squared plate base Vacuum Side • PEEK insulation rings • Central cylinder potential screw • PEEK gas channel • Gas Injection Air Side C Novosibirsk - NIBS - 07/09/2018 24
Setup • Central cylinder Vacuum Side Air Side C Novosibirsk - NIBS - 07/09/2018 25
Setup • Central cylinder • Internal Quartz tube Vacuum Side Air Side C Novosibirsk - NIBS - 07/09/2018 26
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