The objectives of this WP are to develop the test facility, validate the physical quantity ranges and test the instrument. The test facility will be based on a previously developed equipment which can simulate a representative environment in terms of dust charging and transportation. It will allow measuring the E-field needed to move charged dust particles, the current resulting from their impact onto the dust electrodes and the charging level of those particles (surface potential).
Objectives
Develop the test facility, validate the physical quantity ranges and test the instrument.
Based on a previously developed test facility, a laboratory test setup that can simulate a representative environment in terms of dust charging and transportation will be developed to measure the E-field needed to move charged dust particles, the current resulting from their impact onto the dust electrodes and the charging level of those particles (surface potential). Those results are the key parameters to consolidate the determination of the physical quantity ranges computed in task 1.1 and will be used to define the instrument’s requirements. To validate the measurement of the current due to the impact of charged particles onto the dust electrodes, those measurements will be compared to optical methods based on a CCD camera that have already been developed and on optical microscopy.
The same setup will be used to test the E-field probes and dust electrodes.
The Langmuir probes will be tested in an existing plasma chamber.
Several Langmuir probes, E-Field probes and dust electrodes will be tested and compared to select the most
suitable ones.
Lead / Participants
ONERA, BIRA-IASB, CSIC
Description
Task 4.1 Laboratory test setup design and manufacturing (lead: ONERA)
Development of an experimental setup (based on an existing setup and additional laboratory equipment) that will be used to
1) ionise the dust grains,
2) move the charged dust grains horizontally or vertically using electrostatic forces,
3) quantify the displacement of the charged grains by measuring the current resulting from their impact onto the dust electrodes,
4) validate the current measurement method with the existing optical detection method,
5) determine the electric field at the surface of the dust layer.
This experimental setup will be based and benefit from the experience gained over the different setups that have been designed for the DROP chamber at
ONERA.
Task 4.2 Validation of physical quantity ranges (lead: ONERA)
ONERA: Perform measurements with the setup developed in Task 3.1, to determine experimentally for dust grains of different material and dimensions
1) what level of E-field is needed to move different dust grains in different charging conditions (e.g. equivalent to lunar day/night),
2) the current resulting from the collection of charged grains on the electrodes,
3) the electric potential of the dust layer.
Compare the current measurements from 2) with the results obtained with the optical detection method.
Task 4.3 Test and validation of the instrument (lead: ONERA, participants: BIRA-IASB, CSIC)
ONERA: Performance of the same measurements as in Task 4.2, but with the E-field probes and dust electrodes developed in Task 2.5 and the breadboard instrument developed in WP3. Comparison of the different types of probes/electrodes designed in Task 2.3. For the dust collector, comparison between the measurements performed with laboratory equipment and measurement performed with the breadboard. The dust collector will be placed in ONERA’s DROP vacuum chamber that is specially designed for dust experiments. Depending on technical considerations (mainly volume constraints), the dust collector electronics will be deployed either within or outside the chamber.
For the E-field probes, comparison between the dust charging level estimated by the E-field probes and the Kelvin probe-based measurement. The Langmuir probes will be tested in a controlled plasma chamber. The chamber that will be used is the JONAS chamber at ONERA that has the required dimensions, cleanliness and instrumentation
for scientific instrument test and qualification. Writing of the documentation (measurement report).
BIRA-IASB: Contribution to the definition of the test procedure and parameters.
CSIC: Support for SW and EGSE.
Task 4.4 Theoretical models improvement (lead: ONERA)
ONERA: Using the results of tasks 4.2, 4.3 and 5.2, update the models used in Task 1.1.