{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/74916"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/74916","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"An Electrometer Design and Characterization for a CubeSat Neutral Pressure Instrument","abstract":"Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, which can trigger instabilities that severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI consists of an ionization chamber and a logarithmic electrometer circuit. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a design topology for the Rev. 2 electrometer and a derivation of the theoretical circuit transfer function. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions.","abstract_html":"Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, which can trigger instabilities that severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI consists of an ionization chamber and a logarithmic electrometer circuit. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a design topology for the Rev. 2 electrometer and a derivation of the theoretical circuit transfer function. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions.","abstract_has_math":false,"creators":["Rohrer, Todd Edward Bloomquist"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Electrical Engineering","degree_department":"Electrical and Computer Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Earle, Gregory D."],"committee_members":["Wang, Anbo","Sable, Daniel M."],"year":2017,"date_issued":"2017-02-02","date_published":"2017-02-02","updated_at":"2026-07-22T22:18:53Z","subjects":["Space","Spacecraft","CubeSat","Instrumentation","Analog Circuit Design"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:9440"],"render_values":[{"text":"vt_gsexam:9440","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/74916","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Earle, Gregory D."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Wang, Anbo","Sable, Daniel M."]},{"key":"dc:contributor.department","label":"Department","values":["Electrical and Computer Engineering"]},{"key":"dc:creator","label":"Author","values":["Rohrer, Todd Edward Bloomquist"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-02-03T09:00:23Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-02-03T09:00:23Z"]},{"key":"dc:date.issued","label":"Date","values":["2017-02-02"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Space","Spacecraft","CubeSat","Instrumentation","Analog Circuit Design"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:9440"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/74916"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, which can trigger instabilities that severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI consists of an ionization chamber and a logarithmic electrometer circuit. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a design topology for the Rev. 2 electrometer and a derivation of the theoretical circuit transfer function. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, oscillations that transfer energy from weather events or other disturbances through the atmosphere and can severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI is part of the instrument payload for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE). LAICE is a CubeSat–a small satellite format utilizing commercial o↵-the-shelf (COTS) parts to minimize development cycle time and cost–developed with the goal of observing atmospheric gravity waves. SNeuPI utilizes an ionization chamber, which ionizes neutral gas molecules, an ion detector that ouputs an electron current proportional to ion density, and an electrometer circuit, which outputs a voltage logarithmically related to the magnitude of the detector electron current. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a circuit design for the Rev. 2 electrometer and a mathematical derivation of the relationship between its input current and output voltage. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the LAICE mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["An Electrometer Design and Characterization for a CubeSat Neutral Pressure Instrument"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Earle, Gregory D."],"dc:contributor.committeemember":["Wang, Anbo","Sable, Daniel M."],"dc:contributor.department":["Electrical and Computer Engineering"],"dc:creator":["Rohrer, Todd Edward Bloomquist"],"dc:date.accessioned":["2017-02-03T09:00:23Z"],"dc:date.available":["2017-02-03T09:00:23Z"],"dc:date.issued":["2017-02-02"],"dc:description.abstract":["Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, which can trigger instabilities that severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI consists of an ionization chamber and a logarithmic electrometer circuit. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a design topology for the Rev. 2 electrometer and a derivation of the theoretical circuit transfer function. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions."],"dc:description.abstractgeneral":["Neutral gas pressure measurements in low Earth orbit (LEO) can facilitate the monitoring of atmospheric gravity waves, oscillations that transfer energy from weather events or other disturbances through the atmosphere and can severely disrupt radio frequency communication signals. The Space Neutral Pressure Instrument (SNeuPI) is a low-power instrument detecting neutral gas density in order to determine neutral gas pressure. SNeuPI is part of the instrument payload for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE). LAICE is a CubeSat–a small satellite format utilizing commercial o↵-the-shelf (COTS) parts to minimize development cycle time and cost–developed with the goal of observing atmospheric gravity waves. SNeuPI utilizes an ionization chamber, which ionizes neutral gas molecules, an ion detector that ouputs an electron current proportional to ion density, and an electrometer circuit, which outputs a voltage logarithmically related to the magnitude of the detector electron current. The Rev. 1 SNeuPI electrometer prototype does not function as designed. A Rev. 2 electrometer circuit must be designed and its performance characterized across specified operating temperature and input current ranges. This document presents a circuit design for the Rev. 2 electrometer and a mathematical derivation of the relationship between its input current and output voltage. Component selection and layout are discussed. A range of predicted operating input currents is calculated using modeled neutral density data for a range of local times, altitudes, and latitudes corresponding to the conditions expected for the LAICE mission. Laboratory test setups for measurements performed both under vacuum and at atmospheric pressure are documented in detail. Test procedures are presented to characterize the performance of the Rev. 2 electrometer at a range of controlled operating temperatures. The results of these tests are then extrapolated in order to predict the operation of the circuit at specified temperatures outside of the range controllable under laboratory test conditions. The logarithmic conformance, accuracy, sensitivity, power consumption, and deviations from expected response of the circuit are characterized. The results validate the electrometer for use under its expected flight conditions."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:9440"],"dc:identifier.uri":["http://hdl.handle.net/10919/74916"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Space","Spacecraft","CubeSat","Instrumentation","Analog Circuit Design"],"dc:title":["An Electrometer Design and Characterization for a CubeSat Neutral Pressure Instrument"],"dc:type":["Thesis"],"thesis:degree_discipline":["Electrical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:53Z"}