EPIC
Electric Propulsion Competitiveness Workshop
Brussels
25 -28 November 2014
Test Facilities and Advanced Diagnostics for EP
Fabrizio Scortecci
AEROSPAZIO Tecnologie s.r.l. - Rapolano Terme, Siena, Italy
AST.1
EP Testing Centre
Electric Propulsion test services
•
•
•
performance testing of plasma and ion thrusters
endurance, lifetime and more in general
qualification testing according to customers
standards
EP compatibility with spacecraft subsystems
– backflow toward the spacecraft
– erosion and sputtering of S/C surfaces
Astrium RIT-22
Thales HEMPT
Fakel SPT-100
Astrium RIT-XT
AST.2
The Test Laboratory
Electric Propulsion test services
•
•
•
•
The present laboratory features 500 sq.m laboratory and 300 sq.m. offices
Two Large Vacuum Test Facilities each with a volume >100 cu.m. are presently operated
Additional Medium and Small vacuum facilities are available
EMI/EMC test facility under commissioning
AST.3
LVTF-1 Test Facility
Characteristics:
Heritage:
- 3.8 m Ø x 11.4m L , 120 cu.m. Volume
- Chevron beam target, Water/GN2 cooling, P>25kW
- Graphite lining over the chevron target and the cylinder
- Forevacuum system allowing p<1xE-2 mbar in less than 4h
- High vacuum system allowing p<1xE-7 mbar in less than 12h
- Chamber heat conditioning allow static vacuum p<3xE-8 mbar
- Cryogenic pump speed on Xe >160.000 l/s over long duration test
- Over 10kg of Xe cryocondensation before regeneration needs
- Facility reliability >90% over long duration testing
- over 500h testing of Astrium RIT-XT
- over 5.000h testing of Astrium RIT-22
- over 5.200h testing of Thales HEMPT
- over 300h testing of several Fakel SPT-100 models
Ongoing programmes:
- HEMP-TIS qualification programme
AST.4
LVTF-1 (HEMP-TIS upgrade)
Special test setup:
- all the graphite protections have been fully removed from any part of the facility
- new Aluminium panels have been installed in a concentric-cylindrical chevron shape
- the accurate design was performed by the Max-Planck-Institut für Plasmaphysik - Greifswald under Thales supervision
AST.5
LVTF-2 Test Facility
Characteristics:
Heritage:
- 3.8 m Ø x 12.5m L , 140 cu.m. Volume
- Chevron beam target, Water/GN2 cooling, P>25kW
- Graphite lining over the chevron target and the cylinder
- Dry pumping system at all stages
- Mag-lev Turbomolecular pumps
- Forevacuum system allowing p<1xE-2 mbar in less than 4h
- High vacuum system allowing p<1xE-7 mbar in less than 12h
- Chamber heat conditioning allow static vacuum p<3xE-8 mbar
- Cryogenic pump speed on Xe >180.000 l/s over long duration test
- Facility reliability >90% over long duration testing
- Commissioned in 2011
- Performance testing of single and HET clusters
- Performance testing of Helicon thrusters
- Sputtering testing of HET plume over S/C surfaces
- Thermal vacuum testing for ESA and ASI programmes
Ongoing programmes:
- High power EP thrusters testing
- EMI/EMC testing
AST.6
EMI/EMC Test Facility
In-vacuum EMI/EMC test facility
Shielded chamber internal dimensions before
absorbers installation
6.0 x 5.2 x 3.3 m
The EMI room is connected to the LVTF-2 test facility
Shielding performance before the chamber upgrade
Frequency Field
Shielding (>)
10 KHz
Magnetic
70 dB
100 KHz
Magnetic
110 dB
1 MHz
Magnetic
110 dB
100 MHz
Electric
140 dB
500 MHz
Plane Wave
110 dB
1 GHz
Plane Wave
110 dB
10 GHz
Microwave
100 dB
18 GHz
Microwave
100 dB
40 GHz
Microwave
90 dB
AST.7
EMI/EMC Test Facility (2)
4.1 m
∅ 1m
An optimal arrangement of different types
absorbers has been designed to cover the
walls, including:
• Ferrite lining + hybrid absorbers
• 24” and 30” absorbers
Semi-anechoic room useful internal
dimensions after absorber installation:
4.8 x 4.1 x 2.7 m
4.8 m
AST.8
EMI/EMC Test Facility (3)
Connection to LVTF-2 test facility
LVTF-2
∅ 3.8 m x L 12.5m
Pump speed > 180.000 l/s on Xe
∅
1m Gate Valve
∅ 1m
x L 1.5m service chamber
S2 glass + Epoxy
Pyramidal beam dump
AST.9
EMI/EMC Test Facility (4)
New shielding test are
actually ongoing to
asses the new
performance after the
Gate Valve Installation
AST.10
Ground Support Equipment
EGSE & FGSE
• Test Power Supplies for Hall Thrusters from 100 W to 10kW
Power
• Xenon Propellant Feeding System from 1 sccm to 200 sccm
AST.11
Diagnostics Test Equipment
Thrust Balance
• Parallelogram with zero deflection type (null reading)
• The stiffness of the hinges can be chosen so as
thrusters of different weight and thrust can be
accommodated.
• Reconfigurable structure allowing different range of
measurements (hundreds of mN, mN, and hundreds
of uN ranges)
• Typical accuracy in the range of +/- 0.5% over a
single dedicated test, and +/- 2% over long duration
testing
Thrust balance installation in the MVTF-1 test facility
AST.12
Diagnostic Test Equipment (2)
Probe set-up on the diagnostics boom
•
The diagnostics boom is moved by a stepper motor
which is controlled by a PC based system
•
The boom can be rotated around the thruster axis.
•
Typical range of rotation depends from the
mechanical constrains placed around the thruster
(e.g. –100 to 100 deg with thrust balance installed).
•
34 Faraday Probes placed at different angular
positions on the arm (each 5 deg from β =-80 to +85
deg). It allow to measure the ion current 1 m from
the thruster at different angles from the centerline.
•
additional probes are mounted on the boom for
special measurements.
•
2 RPA are available on the diagnostic boom.
RPA
Probe b
Probe a
AST.13
Beam Diagnostics
Faraday probes
current density plot for each Faraday probe
current density 3D plot
current density contour plot
beam current
beam divergency
beam axis deviation
test report generated automatically
10
Co nto ur m ap o f Curre nt De ns ity (inte rpo late d)
FP11 (β = -0.54°)
1
80
60
40
0
0.5
1
2
7
4
10
5
-20
-1
2
6
3
1
2
3
0
3
5
6
4
β (°)
20
0.5
2
10
0 .5
Curre nt De ns ity (A/m )
•
•
•
•
•
•
•
1
0 .5
-40
-60
10
-2
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
α (°)
10
20
30
40
50
60
70
80
90
-80
-80
-60
-40
-20
0
20
40
60
80
α (°)
AST.14
Beam Diagnostics (2)
The Retarding Potential Analyser (RPA)
1.8
x 10
-5
Origina l Da ta
S moothing S pline
1.6
•
•
•
•
The RPA measure the energy of the ions emitted from the
thruster at different angles from the centerline
The first grid is electrically isolated from the probe
The second grid is biased to a constant negative potential to
repel all plasma electrons from the collector
The third one is the ion retarding grid and is connected to a
variable high voltage power supply
The ion current to the collector is measured by using a Picoammeter
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1000
9
x 10
1200
1400
1600
1800
2000
2200
2400
2000
2200
2400
Io n Vo ltag e Dis tributio n
-8
8
7
6
5
dI/dV (A/V)
•
4
3
2
1
0
-1
1000
1200
1400
1600
1800
Ene rgy / Cha rge (V)
AST.15
Beam Diagnostics (3)
Langmuir Probes
•
•
•
Plasma potential
Electron energy distribution
The probes can be mounted on the rotation boom to measure
the far field or in a fast sweeping mechanism to investigate the
near field
Thruster
Langmuir 1
20°
Firing Direction
Langmuir 2
Langmuir Movement System
AST.16
Beam Diagnostics (4)
Emission Spectroscopy
• electron temperature
• neutral Xe density
• charged ions Xe density
AST.17
Beam Diagnostics (5)
Laser Induced Fluorescence (LIF)
Collimator 2
•
•
•
•
•
3.5
Lock-in signal [V]
3.0
X=0 mm; Z=-48 mm;
Y=0mm
Y=+8.5mm
Y=+17mm
Y=-8.5mm
Y=-17mm
4
Collimator 1
reference line at 834.745 nm
LIF signal at 834.724 nm
3
Lock-in output [V]
4.0
neutral Xe velocity
single charged Xe velocity
axial and radial velocity components
thruster mounted on a 3 axis displacement system for fast sweep
spatial resolution 1x1x8 mm
2.5
2.0
1.5
2
1
1.0
0.5
0
0.0
-12 -10
-8
-6
-4
-2
0
2
4
6
8
10
12
14
Frequency [GHz]
Radial velocity distribution as a function of the Y direction
-30
-25
-20
-15
-10
-5
0
5
Frequency [GHz]
Most probable axial velocity measurement at V=250 V and
0.7 mg/sec Xe flux (left) and an example of the LIF signal
(right).
AST.18
Beam Diagnostics (6)
E x B Probe
The diagnostics is under development in the frame of the
ESA Program “Qualification of the AEPD System as a
Standard On-ground Tool for Electric Propulsion
Thrusters”, ESA Contract No. 4000107451/12/NL/RA
• multiple charged species fractions
• multiple charged species velocity
Magnetic assembly analysis
30
AST.19
Additional Test Facilities
• Small Vacuum Test Facilities
• The SVTF-1 / 2 / 3 are mainly used for :
• regular vacuum gauges verification comparing to
calibrated gauges
• Spectrometers check and verification
• cathode testing
• Medium Vacuum Test Facilities
• The MVTF-1 is mainly used for low power thruster test
• 1.3 m Ø x 3 m L , 4 cu.m. Volume
• Graphite lining over the chevron target and the cylinder
• High vacuum system allowing p<1xE-6 mbar (p<1xE-7
mbar after chamber heat conditioning static vacuum)
• Cryogenic pump speed on Xe >10.000 l/s
• Beam diagnostics
• Thrust balance
• Spectroscopic and LIF diagnostics
AST.20
Engineering Activities
Vacuum Test Services
•
•
•
•
•
Leak-check services
Residual gas analysis
Special flanges/adapter design/manuf.
Vacuum harness design/manuf.
Vacuum chambers design/manuf.
Cryogenic systems developments
• Cryostats design/manuf.
• LN2 supply/lines design/manuf.
• LN2 phase/separators design/manuf.
Electronics and management of data
• Data Acquisition & Control for complex systems
• Networking & Communications in harsh
environments
• Specific HW and SW developments
AST.21
AEROSPAZIO TECNOLOGIE s.r.l.
Rapolano Terme, Siena, Italy
www.aerospazio.com
Thank You
AST.22