Failures encoutered during build and test of swea sensor instrument
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Failures encoutered during build and test of Swea sensor instrument. Maven / SWEA is a remake of Stereo / SWEA for which 4 models were developped ( 2 X FM + 2 x EM )

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Failures encoutered during build and test of Swea sensor instrument

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Failures encoutered during build and test of swea sensor instrument

Failuresencouteredduringbuild and test of Sweasensor instrument

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

  • Maven/ SWEA is a remake of Stereo/ SWEA for which 4 modelsweredevelopped (2 X FM + 2 x EM)

  • The proposal to CNES for Maven/ SWEA was to build an instrument for MAVEN as close as possible to Stereo one (limitedfunding and manpower)

  • A limitednumber of changes wereidentified by IRAP and SSL (Stereo to Maven doc) due to:

    • Different mission profile

    • Stereo anomalies considering datas

    • Improve the instrument

  • These changes inducedsome anomalies, failures or new concerns

  • Somefailures or anomalies werealreadypresent on Stereo

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

Whencommanding HV deflectors to zero, the deflectors HV was not zero.

The samesupply return line wasused to command HV deflectors and to supplyMCPs high voltage,

So whencommanding the deflectors to zerotherewere not zero on deflector HV command but differents positive values depending of differentsMCPs high voltage supplycurrents.

(Deflectors HV offsets did not comply to ICD)

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

  • Proposition:

  • Connect all interface connectorsparewires to analoggroundboth on sensorside and on electronic box side (SSL) to reduce the changingimpedance of analog return line and soreducedeflectors HV command offsets.

  • IRAP to make a calibration of deflectors HV offset vs MCP HV value.

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

Radiation doses expected more important than for StereoMake a new thickerelectronicsboardshousing part (2.5mm). (mech. Part #23)

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

Three M2x4 CHC obturator fixation screwssuspected to be in detector field of view.

Solution:replaced by 3 M2x4 FHC screws as on drawinghere.

Obturatormodified to fit FHC screws.

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

On Maven project, after SSL simulations, it was decided to raise top deflector by 1mm

and drop bottom deflector by 0.3mm to have better deflexion homogeneity.

After this operation, it appeared that part #32 was partly in detector field of view.

Solution:

Slightly modify part #32

(see mechanical parts list & drawing)

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

  • Following part stress analysis: Osram SFH421 LED not qualified

  • Tests according to “EEE-INST-002 Instructions for EEE parts selection, screening, qualification and derating.” were made by Hirex with SSL agreement.

  • LAT tests on samples

  • Life test (1000 hours)

  • Radiation tests up to 20KRad at low dose flow (smaller or equal to 360 rad (SI) per hour)

  • Tests results successfuls

  • (See Hirex reports)

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

Following part stress analyser: Vishay HV resistorhadunderrated voltage

Vishay HTS68 (1GΩ) rated 2KV

Vishay HTS523 (1GΩ) rated 5KV

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

Following part stress analyser:

diodes JANTXV1N6642 has peak inverse voltage overstress (100V)

Werereplaced by JANTXV1N6638 (rated 150V)

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


Failures encoutered during build and test of swea sensor instrument

END

MAVEN-Swea sensor pre-shipping review - December 1-2/2011


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