Terms and Definitions - estec EPL General Description

Arcjet Device that heats a propellant stream by passing a high current electrical arc through it, before expansion through a downstream nozzle.

Hall effect Conduction of electric current perpendicular to an applied electric field in a superimposed magnetic field.

Inductive thruster Device that heats a propellant stream via an inductive discharge before expansion through a downstream nozzle.

Ion thruster Device that accelerates propellant ions by an electrostatic field.

Magnetoplasmadynamic thruster Device that accelerates a propellant plasma by an internal or external magnetic field acting on an internal arc current.

Plasma Heavily ionized state of matter, usually gaseous, composed of ions, electrons, and neutral atoms or molecules, that has sufficient electrical conductivity to carry substantial current and to react to electric and magnetic body forces.

Resistojet Device that heats a propellant stream by passing it through a resistively heated chamber before expansion through a downstream nozzle.

Thrust Unbalanced internal force exerted on a rocket during expulsion of its propellant mass.

Specific impulse Measure of how efficiently the propellant is ejected by the thruster, directly proportional to the average propellant exhaust velocity

2 REFERENCE DOCUMENTS

RD01 uNTB-VTP-Seismic-2010-v1r0 Seismic Monitoring Of EPL - Test Plan v1.0

RD02 TEC-MP-EPL-WI003 FEEP Operational Manual vR2A

Manufacturer Reference Klok_Estecgigant_OM_R2A

RD03 TEC-MP-EPL-D002 Galileo Operational Manual v2.0

RD04 TEC-MP-EPL-WI001 Gigant Operational Manual vR2B

Manufacturer Reference Klok_Estecgigant_OM_R2B RD05 ALTA_CUP_TN-04_1.1 Corona Test Facility Final Design Report v1.1

RD06 TEC-MP-EPL-WI032 Corona Trolley Operational Manual v1.0

Manufacturer Reference ALTA_COR_TN-02_1.0

RD07 TEC-MP-EPL-D006 Corona Operational Manual v2.2

Manufacturer Reference ALTA_CUP_TN-06_2.2- 01

RD08 TEC-MP-EPL-D004 Electron Operation Manual v3.0

RD09 TEC-MP-EPL-D005 MicroNewton Operational Manual v2.0

RD10 ALTA_SPF_TN-03_1.1 Small Plasma Facility Design Report v1.1

RD11 ALTA_PFE_TN-011 Small Plasma Facility Control System Upgrade, User Manual v1.0

RD12 TEC-MP-EPL-D047 EPL Flow Rig User Manual v1.0

RD13 TEC-MP-EPL-WI008 Operational Manual MTAX504 v1.0

RD14 TEC-MP-EPL-D044 ALTA 1 Axis TS Operational Manual v2.0

RD15 ALTA_LTB_TN-01_1.3 LTB User Manual v1.3

RD16 ALTA-CO2-ED-01 Corona Beam Diagnostics Design Report v1.0 RD17 ALTA-CO2-TN-01 Corona Beam Diagnostics Software User Manual v1.0

RD18 ALTA-GIG-TN-01 Gigant Beam Diagnostics User Manual v4.1

RD19 ALTA-GIG-ED-02 Plume Diagnostics for the Gigant Facility, Detail Design Report v1.0

RD20 ALTA_SPF_TN-42_1.1 RPA User Manual v.1.1

RD21 ALTA_SPF_TN-43_1.0 Faraday And Langmuir User Manual v1.0 RD22 ALTA_SPF_TN-44_1.0 SPF Diagnostics User Manual v1.0

RD23 ALTA_HT100_UM_1 HT100 User Manual v1.0

RD24 UGI-EP 11-2007-EMI-004-ESTEC User Manual GIES15 v1.4

RD25 ALTA-SPF-TN-32 XR100 Resistojet Complete System User Manual v2.1

RD26 QINETIQ/EMEA/S&DU/UG0708032 Low Power HET Hollow Cathode User Guide And Acceptance Test Procedure 1.1

RD27 - SHC1000 Electron Source Manual v1.0

RD28 TEC-MP-EPL-P003 Thrust Measurement Procedure v5.0

RD29 TEC-MP-EPL-P004 Electric Power Measurement Procedure v3.2

RD30 TEC-MP-EPL-P005 Mass Flow Measurement Procedure v4.0

RD31 TEC-MP-EPL-D048 µNTB User Manual v1.1

RD32 TEC-MP-2013-1227-KD Determination of the pumping speed and wall temperature in the FEEP vacuum chamber, Test Report

RD33 TEC-MP-2012-1131-DDC Langmuir Probe and Thermocamera Commissioning Test Report

4 INTRODUCTION

This document is an introduction to some of the terms, facilities, equipment, test and measurement methods, and safety /environmental conditions of the ESA Propulsion Laboratory (EPL).

The EPL performs R&D testing activities and support to projects related to propulsion. The laboratory is ISO 9001 certified and has ISO 17025 Accreditation for direct and indirect measurement of thrust (the latter calculated from current and voltage measurement), mass flow, and electrical parameters (current and voltage) of the Propulsion System (thruster, cathode/neutralizer and power unit).

5 INFRASTRUCTURE

The EPL is located in the Ek building at ESA-ESTEC (Figure 1 below).

Figure 1: EPL building (up: from outside, down: from inside).

The EPL is divided into six rooms (see schematic Figure 2):

• A changing room (Ek032) by which the main laboratory is accessed.

• An assembly room (Ek032e) in which are stored critical devices and chemicals and which can be used to prepare test set-ups.

• A control room (Ek034) mostly used as a meeting room.

• An archive room (Ek036) in which is stored the EPL documentation and software.

• A storage room (Ek038) in which is stored hardware and consumables.

• The main laboratory (Ek045), with seven vacuum chambers and a flow rig bench.

Figure 2: EPL layout.

The total surface of the EPL is 12 x 30 m.

The main laboratory and the assembly room have an environment suitable to implement an ISO clean room, class 8¹ environment and conditions upon customer request. Those conditions can be applied if asked specifically by a customer.

A seismic block was installed in the EPL to prevent environmental noise perturbations. The seismic bloc is a 4.2 x 16.6 m concrete block of about 160 tons. It is mounted on 8 Airmount Firestone air springs for vibration isolation. Mechanical isolation from the laboratory is maintained by passive damping and has a 1 Hz cut-off frequency with a 20 dB per decade roll-off. The seismic block has a natural resonance of 0.8 Hz. For further information refer to RD01.

1 This number refers to ISO 14644-1 standards.

Figure 3: Picture of the seismic bloc in the EPL (RD01).

6 SAFETY AND ENVIRONMENTAL CONDITIONS 6.1 Safety conditions

The EPL, as part of the Mechanical Engineering Department (TEC-M), in the Directorate of Technical and Quality Management (D/TEC), completed in 2003 a Risk Assessment and Evaluation performed by a Certified Safety Institute.

This is subject to annual review and forms part of the developing Safety Management System.

In summary the main hazards are represented by:

• High voltages;

• Cryogenic liquids;

• Chemicals and alkaline metals.

Safety equipment, including personal protective equipment is available in the EPL and must be used by all staff, contractors and visitors during testing as necessary.

6.2 Environmental conditions

• The temperature in the EPL is maintained at 23° ± 5°.

• The humidity in the EPL is maintained at 50% ± 20%.

These are maintained by ESTEC Site Management Division (OPS) and monitored at all time by the EPL using a calibrated temperature and humidity probe (see section 8.5.3).

7 GENERAL EPL TESTING METHODS 7.1 Measurement procedures

The main goal of the EPL is to give support to projects in all propulsion related issues matters. This includes specific dedicated tests but also more general R&D testing activities.

When testing Propulsion Systems the three main parameters measured are:

• Thrust produced (T)

• Electrical power consumed (P)

• Propellant mass flow consumed (mf)

These three quantities are used to derive specific impulse (

g

parameters (thrust, power, mass flow, specific impulse and efficiency) are the critical parameters for a propulsion system.

The laboratory is ISO 17025 accredited for direct and indirect measurement of thrust and direct measurement of electrical power and mass flow. The corresponding measurement procedures can be found respectively in RD28, RD29 and RD30.

The EPL uses a wide variety of instruments to follow these procedures:

• Direct thrust measurements are performed with calibrated/validated commercial load cells or specifically designed balances, described in section 8.2.1.

• Direct mass flow measurements are performed with calibrated mass flow controllers, described in section 8.4.1.

• Direct electrical power measurements are performed using the readings of the used power supplies or digital multimeters, described in section 8.5.

• Indirect thrust (for electric thrusters) is inferred from the electrical measurements (currents and voltages) and beam properties of the thruster.

7.2 Validation and Measurement Traceability

The afore mentioned measurement procedures are validated by the ISO17025 accreditation. More general measurement procedures (such as temperature or pressure measurements) are adopted as-is without accreditation.

All critical measurement equipment used is calibrated by external calibration laboratories traceable to (inter) national standards.

8 EQUIPMENT 8.1 Vacuum facilities

The EPL has seven vacuum facilities:

1. FEEP 2. GALILEO 3. GIGANT 4. CORONA 5. ELECTRON 6. MICRONEWTON

7. SMALL PLASMA FACILITY (SPF)

Each facility consists of a vacuum tank equipped with dedicated pumping systems and sensors. The tanks provide flanges of different sizes for a wide variety of feedthroughs.

Most of the facilities also have an automated pumping control unit.

The EPL has recently acquired a flow bench for future water hammer measurements. This facility is being prepared for commissioning. In its first version, the flow bench will be used for chemical propulsion component leak and performance testing.

8.1.1 FEEP (VF #1)

Figure 4: FEEP

FEEP has the following characteristics:

• It consists of a 1.3 x 0.8 m main chamber and a 0.5 x 0.3 m hatch.

• The lowest achievable pressure is 10^-8 mbar.

• Its theoretical pumping capacity in nominal test conditions is 6000 L/s N2: - 1 rotary pump (40 m³/h)

- 1 root pump (150 m³/h) - 1 turbo pump (560 L/s N2)

- 3 cryopumps (800, 2000 and 3200 L/s N2)

• It is equipped with a bake-out system

• The pumping system can be controlled through a feedback control system (Eurotherm).

The actual pumping speed of the facility is 1610 L/s for the hatch and 4560 L/s for the main chamber of N2 with both the turbo- and cryopump running as described in RD32.

The operation manual can be found in RD02.

This facility is mainly dedicated to micro-Newton and milli-Newton field-emission propulsion testing.

8.1.2 GALILEO (VF #2)

Figure 5: GALILEO.

GALILEO has the following characteristics:

• It consists of a 1.2 x 1 m vertical cylinder chamber

• The lowest achievable pressure is 10^-8 mbar

• Its theoretical pumping capacity in nominal test conditions is 64000 L/s N2: - 1 rotary pump (40 m³/h)

- 1 root pump (150 m³/h) - 1 turbo pump (450 L/s N2) - 1 cryopump (5000 L/s N2)

- 2 cryoheads (50 x 50 cm plates, 29500 L/s N2).

• The pumping system can be controlled through a feedback control system (Klok Vacuum service).

• It is equipped with a bake-out system which can be controlled through the above feedback control system.

The operational manual can be found in RD03.

This vacuum chamber is mainly dedicated to thrust and mass-flow test of cold-gas, resistojets, miniaturised Hall-effect thrusters and FEEP propulsion systems and components (cathodes).

8.1.3 GIGANT (VF #3)

Figure 6: GIGANT.

GIGANT has the following characteristics:

• It consists of a 2.5 x 1.6 m main chamber and a 0.8 x 0.4 m hatch.

• The lowest achievable pressure is 10^-9 mbar.

• Its theoretical pumping capacity in nominal test conditions is 102200 L/s N2: - 1 rotary pump for seals (8 m³/h)

- 1 scroll pump (40 m³/h) - 1 root pump (150 m³/h) - 2 turbo pump (1000 L/s N2)

- 2 cryopumps (800 and 10000 L/s N2) - 2 cryoheads (50 x 50 cm, 29500 L/s N2 each) - 2 cryoheads (25 x 55 cm, 16200 L/s N2 each)

• It is equipped with a bake-out system and a liquid nitrogen cooled shroud.

• The pumping system can be controlled through a feedback control system (Eurotherm).

The operational manual can be found in RD04.

This facility is mainly dedicated to low/medium-power ion engines and Hall-effect thrusters and mN field-emission propulsion testing.

8.1.4 CORONA (VF #4)

Figure 7: CORONA.

CORONA has the following characteristics:

• It consists of a 4 x 2 m main chamber and a 1 x 1 m hatch.

• The lowest achievable pressure is 5.10^-8 mbar.

• Its theoretical pumping capacity in nominal test conditions is (RD05): 154800 L/s N2 (≈ 70000 L/s Xe):

- 3 scroll pumps (4.8, 26. 3 and 26.3 m³/h each) - 1 screw pump (270 m³/h)

- 1 turbo pump (2050 L/s N2) for the main chamber - 1 turbo pump (1100 L/s N2) for the hatch chamber - 1 cryopump (10000 L/s N2)

- 2 rectangular cryoheads (0.3 m², 35700 L/s N2 each) - 2 octagonal cryoheads (0.35 m², 41700 L/2 N2 each)

• It is equipped with a bake-out system and a liquid nitrogen cooled shroud.

• A pneumatic trolley (RD06) stands in the hatch so that test equipment can be accessed through the hatch without having to open the main vessel.

• The pumping system can be controlled through a software based feedback control system (supplied by ALTA Spa.).

The operational manual can be found in RD07.

This facility is mainly dedicated to medium/high-power ion engines and Hall-effect thrusters.

The actual pumping speed of the facility is 52130 L/s of Xe as described in RD33.

8.1.5 ELECTRON (VF #5)

Figure 8: ELECTRON.

ELECTRON (Figure 8) has the following characteristics:

• 0.8 x 0.5 meter chamber

• The lowest achievable pressure is 10^-7 mbar

• Its theoretical pumping capacity in nominal test conditions is 260 L/s N2.

- 1 membrane pump (4 m³/h) - 1 turbo pump (260 L/s N2) The operational manual can be found in RD08.

This vacuum chamber is mainly dedicated to neutralizer systems (field-emission or thermionic) or components testing.

8.1.6 MICRONEWTON (VF #6)

Figure 9: MICRONEWTON.

MicroNewton (Figure 9) has the following characteristics:

• It consist of a 0.65 x 0.5 meter chamber, mounted on a movable rack.

• The lowest achievable pressure is 10^-7 mbar.

• Its theoretical pumping capacity in nominal test conditions is 500 L/s N2 - 1 moveable rotary and turbo pumping unit (4 m³/h, 260 L/s) - 1 ion pump (500 L/s N2)

The operational manual can be found in RD09.

This facility is mainly dedicated to electric propulsion components testing.

8.1.7 SMALL PLASMA FACILITY (VF #7)

Figure 10: SPF.

Small Plasma Facility (SPF, Figure 10) has the following characteristics:

• It consist of a 3.35 x 2 meter main chamber with a 1 m x ∅1 m hatch.

• The lowest achievable pressure is 10^-7 mbar.

• Its theoretical pumping capacity in nominal test conditions is 69600 L/s N2 - 1 roots pump (1000 m³/h)

- 1 primary pump (30 m³/h) - 1 screw pump (250 m³/h) - 1 turbopump (2200 L/s N2)

- 2 cryoheads (20 x 120 cm each, 28500 L/s N2 each) - 1 cryopump (10000 L/s N2)

- 1 turbopump on the hatch (400 L/s N2) - 1 scroll pump on the hatch (30 m³/h)

• It is equipped with a liquid nitrogen cooled shroud.

• The pumping system can be controlled through a software based feedback control system (supplied by ALTA Spa.).

The design report can be found in RD10 and the operational manual RD11.

The facility can be used both for Aerothermodynamics experiments and EP contamination experiments.

One RPA probe is yet to be installed.

8.1.8 Flow Rig

The Flow Rig is a test system, used by the EPL for the performance testing of components intended for use within a chemical propulsion system. The objective of the Flow Rig is to measure the pressure drop of water passing through a test component installed within the testing section of the Flow Rig and at a later date, water hammer effects.

The Flow Rig requires that pressures, temperatures and mass flow of the working fluid are measured in order to determine the performance of a test component.

The working fluid used for the Flow Rig is distilled water. The pressure drop characteristics of the water are measured throughout the system. This allows a good approximation to be made of the characteristics that would be expected when using other fluids by comparing the thermodynamic properties of both the water and the working fluid intended for use.

Test procedures have been written for pressure drop tests, and the first test campaign has been done. But an evaluation still needs to be done, to achieve full commissioning.

The user manual can be found in RD12.

A picture of the installation is given in Figure 11.

Figure 11: Flow Rig.

8.2 Diagnostic systems 8.2.1 Thrust balances

Five direct thrust measurement balances are available in the EPL. Table 1 below lists the characteristics of each balance.

Table 1: EPL balances.

Balance Reference

Document Picture Manufacturer Range/

Resolution

Location

compatibility Calibrated Measurement procedure Low Thrust Balance

(LTB) RD15 Figure 14 ALTA 40 mN / 0.2 mN Gigant, Corona,

Figure 12: AX504 (left) and XP2004S (right) Mettler Toledo load cells.

Figure 13: 1-Axis optical thrust stand.

Figure 14: LTB

Figure 15: µNTB

8.2.2 Plasma diagnostic systems

GIGANT, CORONA and SPF are all equipped with beam diagnostic arms.

SPF is also equipped with a back-flow diagnostics system.

8.2.2.1 CORONA diagnostic system

The CORONA diagnostic system is based on a vertical arm which allows a 180˚horizontal span (Figure 16). The arm is equipped with:

• 11 Faraday probes

• 1 3.5 kV Retarded Potential analyser (RPA)

• 1 triple Langmuir probe

• 1 Pyroview Uncooled IR Camera

The probes are connected to a dedicated DAQ. Detailed information can be found in RD16 and RD17.

Figure 16: CORONA diagnostic arm

8.2.2.2 GIGANT diagnostic arm

The GIGANT diagnostic system is based on a horizontal arm. It allows a 180˚ vertical span. It is mounted on a translation structure which allows translating it in the beam direction.

The GIGANT diagnostic arm (Figure 17) is equipped with:

• 11 Faraday probes

• A 1 kV and a 10 kV RPA

More information can be found in RD18 and RD19.

Figure 17: GIGANT diagnostic arm

8.2.2.3 SPF diagnostic system

SPF is equipped with a similar arm to that of CORONA.

On the SPF diagnostic arm (Figure 18) one can find:

• 12 Faraday cups

• One 1.25 kV RPA

More information on these probes and the arm can be found in RD20, RD21 and RD22.

Figure 18: SPF diagnostic arm.

SPF is also being equipped with a set of back-flow diagnostics installed on the hatch trolley and a separate arm (Figure 19) which include:

• 2 low voltage (100 Volts) RPA probes

• 2 Faraday cups, similar to the probes installed on the rake arm

• 1 Langmuir probe, operable in 2 or 3 electrodes mode

• A spectrometric system for optical emission measurements

• 1 QCM sensor

The design reports and user manuals are given in RD20, RD21 and RD22.

Figure 19: SPF back-flow diagnostic system and Langmuir probe/Spectrometer.

8.3 Test Items

The EPL owns several test items used to check the EPL diagnostic systems and perform internal R&D activities. The test items owned by the EPL are:

• The low power plasma source HT100, developed by ALTA SpA (RD23)

• The ion source GIES15, developed by the University of Giessen (RD24)

• 2 low power resistojet system XR100, developed by ALTA SpA (RD25)

• 2 resistojets XR-150, developed by ALTA SpA

• Two hollow cathodes EPL001 and EPL002, developed by QinetiQ (RD26)

• Twohollow cathode SHC1000, developed by Kaufman & Robinson (RD27)

8.4 Physical equipment

8.4.1 Mass Flow Sensors/Controllers

Electronic Pressure Regulators/Sensors

The EPL owns MFS/MFC and EPR in wide range. All are Bronkhorst products. Their signals can be acquired via a Bronkhorst controller unit or via an RS232 cable connected to a DAQ. All these instruments all calibrated once a year by Bronkhorst Nederland B V.. MFS are usually calibrated for use with Xe and EPR for use with N2 (this still allows to use the instruments with other gases). They are listed in Table 2 below.

Table 2: Bronkhorst MFS and EPR owned by the EPL.

Instrument Model Serial

number Range

F-201-CV-100-RAD-11-V M10211653A 5 mg/s Xe

MFC EL-FLOW Flow Bus

F-201-CV-100-RAD-11-V M10211653B 5 mg/s Xe

MFC EL-FLOW Flow Bus

F-201-CV-100-RAD-11-V M10211653C 5 mg/s Xe

MFC EL-FLOW Flow Bus

F-220CV-RAA-11V M5206458A 0.14 mg/s Xe

EPR EL-PRESS Flow Bus

P-502C-RAA-22V M6201552B 10 bar

EPR EL-PRESS Flow Bus

P-602C-RAA-22V M5204768A 30 bar

EPR EL-PRESS Flow Bus

P-602C-RAA-22V M5204775A 30 bar

EPR EL-PRESS Flow Bus

P-602C-RAA-22V M5021498A 30 bar

EPR EL-PRESS Flow Bus

P-602C- RAA -22V M5201498B 30 bar

EPR EL-PRESS Flow Bus

P-502C-RAA-22V M6201552A 2 bar

Instrument Model Serial

number Range

EPR EL-PRESS Flow Bus

P-602CV-6K0A-RAD-22-V M12205034A 6 bar Control Valve F-001AC-LIA-22V M6201552E Ø=0.7

Control Valve F-001AC-LIA-22V M6201552F Ø=1.3

Control Valve F-001AC-LHA-22V M6201552D Ø=0.2

Control valve F-004AC-LVA-22V M2206433C 1 g/s Xe 1 barA / vacuum Control Valve F-001AC-LGA-22V M6201552C Ø=0.05

Controller Unit Controller

E-7600-RDD M4207228C -

Controller Unit Controller

E-7500-RAA M5201498D -

Controller Unit Controller

E-7500-RAA M5201498C -

Controller Unit Controller

E-7500-RAA M11203333A -

Controller Unit Controller

E-7300-RAA M2206433D -

8.4.2 Vacuum gauges

The EPL owns Leybold, Pfeiffer and Varian vacuum gauges.

Leybold vacuum gauges systems usually consist of two gauges, a read-out unit and cables. Each system is calibrated as a whole and it is important to use the gauges with their corresponding read-out system and cables. The instruments are calibrated once a year.

Table 3 lists all the vacuum systems available at the EPL.

Table 3: EPL vacuum gauges.

Manufacturer Model Serial number

Leybold SYS 1/1 TTR211S 15730

Manufacturer Model Serial number

Leybold SYS 4 Center Three 230003

FN: 463

Leybold SYS 12 Center Two 230004

FN: 3156/2012

Manufacturer Model Serial number