1、Lessons Learned Entry: 0598Lesson Info:a71 Lesson Number: 0598a71 Lesson Date: 1998-07-23a71 Submitting Organization: JPLa71 Submitted by: D. Oberhettinger/A. WhittleseySubject: Protect Against Corona Discharge and High Voltage Breakdown (1960s-Present) Abstract: JPL flight projects since the 1960s-
2、 Ranger 6, Mariner Mars, Viking 2, Voyager, Galileo, NSCAT, Magellan, and Mars Observer- have a history of susceptibility to corona when exposed to regimes of critical pressure during ground test and flight. Design, test, and operational procedures are listed that may address spacecraft hardware sus
3、ceptibility to corona-induced damage caused by either flight or ground environments.Description of Driving Event: JPL flight projects have a history of susceptibility to corona when exposed to regimes of critical pressure during ground test and flight:Ranger 6 (in-flight): During launch the camera w
4、as inadvertently powered. In addition a nearby enclosure was insufficiently vented for boost pressure decay. As the spacecraft passed the critical pressure region, a corona discharge occurred, disabling the camera system. The result was a complete loss of imaging data.1971- Mariner Mars (ground): Du
5、ring acceptance testing, it was found that a lack of RF breakdown margin at critical pressure necessitated costly design changes.1971- Mariner Mars (in-flight): Unexpected battery venting caused a brief critical pressure region around the high voltage Canopus star tracker, resulting in a corona disc
6、harge. The arc caused a ground-loop current spike that resulted in the permanent loss of 22 telemetry channels in the Flight Data Subsystem (FDS).1976- Viking 2 (in-flight): The Viking Landers downlink failed while on the surface of Mars. This Provided by IHSNot for ResaleNo reproduction or networki
7、ng permitted without license from IHS-,-,-suggested that the high voltage power converter developed a corona discharge and high voltage breakdown while in the critical CO2 pressure region present near the surface of Mars.refer to D descriptionD 1976- Voyager (ground): Design verification disclosed v
8、oids in certain capacitors which could bleed down to critical pressure after long exposure to vacuum, and could lead to a corona discharge.1988- Galileo (ground): The vendors vacuum chamber was purged with dry nitrogen while the extreme ultraviolet (EUV) instrument was powered. This produced a criti
9、cal pressure region, corona discharge, and failure of the EUV high voltage power supply.1989- NSCAT (ground): Windings added to a traveling wave tube amplifier (TWTA) transformer for test purposes, resulted in increased voltage in the primary windings, which triggered a corona discharge.1989- Magell
10、an (in-flight): The pyrotechnic firing which separated the solid rocket motor, used for Venus Orbit Insertion, resulted in a plasma arc, a ground current loop, and destruction of a significant amount of spacecraft memory.1990- Mars Observer (ground): Due to inadequate insulation of the TWTA, a coron
11、a discharge occurred at critical pressure during evacuation of the vacuum chamber.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Keyword(s): Electrostatic DischargeReference(s):1. JPL D-8208, Design and Fabrication Requirements, Section 3
12、.9: “High Voltage Requirements“, Rev. C, March 15, 1997.2. A. Whittlesey, “MISR Corona Issues,“ JPL IOM 5215-94-75 (MISR DFM # 380), March 17, 1994.3. “Proceedings of the Second Workshop on Voltage Breakdown in Electronic Equipment at Low Air Pressures on March 5-7,1969,“ JPL TM-33447, June 30, 1970
13、.4. “RF Breakdown in Mariner Mars 71 RFS Components and Circuits,“ JPL Lesson Learned No. 3-115; JPL Problem Failure Report (PFR) No. 100789.5. “High Voltage Capacitor Used in Voltage Doubler Circuits for Space Applications,“ JPL Lesson Learned No. 3-117.6. “Traveling Wave Tube Amplifier on Martian
14、Surface: Failure Due to Corona,“ JPL Lesson Learned No. 3-119; Viking Incident Surprise Anomaly (ISA) Report No. 15643, October 13, 1976.7. JPL Galileo PFR No. 44450.8. JPL NSCAT PFR Nos. 52102 & 52103.9. JPL Mars Observer PFR No. F0745.10. JPL Magellan PFR #52235.Lesson(s) Learned: Hazardous corona
15、 events can be induced by both flight and ground environments. Examples include:1. Passage of a spacecraft through a critical pressure region of the atmosphere following launch.2. Partial pressurization of a spacecraft in space due to gas leaks from propulsion systems, batteries, etc.3. Engine firin
16、gs in vacuum or near vacuum which cause plume wrapping.4. Changes in vacuum chamber test facility pressurization which expose powered flight hardware to the critical pressure region.5. Electric fields from low voltage circuitry, such as pyrotechnic device firing circuits.Recommendation(s): Spacecraf
17、t hardware susceptibility to corona-induced damage should be addressed in subsystem design and in test and operational procedures.1. Ensure that ventable products will be vented overboard in spaceflight instead of venting within any enclosures, including blankets.2. The following design measures for
18、 corona avoidance on high voltage circuits, summarized Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-from Reference (1), were recently used in the Multi-Angle Imaging Spectroradiometer (MISR) instrument program (Reference (2): a72 Avoid venting int
19、o regions of intense electric fields, such as the vicinity of power supplies and power wiring.a72 Ensure that all critical voltage regions are properly vented.a72 Use insulation materials of high dielectric strength. Insulating materials with strength greater than 300 volts/mil and a relative dielec
20、tric constant less than 5 are preferred.a72 For high voltages, use only connectors that have been tested to work in the critical pressure region. Also, use only soldering terminals rated for high voltage.a72 Physically isolate the high and low voltage circuits.a72 Test the circuits that may be subje
21、ct to voltage breakdown and/or corona discharge.3. Where the above design measures cannot be accommodated, take protective actions (e.g., power such circuitry off prior to encountering critical pressure regions) during testing and flight to avoid damage.Evidence of Recurrence Control Effectiveness:
22、N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 EnvironmentAdditional Info: Approval Info: a71 Approval Date: 1998-08-07a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
