Physics Commons^™

Ultrahigh Vacuum Cryostat System For Extended Low Temperature Space Environment Testing, Justin Dekany, Robert H. Johnson, Gregory Wilson, Amberly Evans, Jr Dennison

Gregory Wilson

The range of temperature measurements have been significantly extended for an existing space environment simulation test chamber used in the study of electron emission, sample charging and discharge, electrostatic discharge and arcing, electron transport, and luminescence of spacecraft materials. This was accomplished by incorporating a new cryostat system and sample mount, which maintained compatibility with an existing ultrahigh vacuum chamber (base pressure The new two-stage, closed-cycle helium cryostat has an extended sample temperature range from450 K, with long-term controlled stability of The new capabilities in this chamber have been employed to study the temperature dependence of materials properties critical to …

Charging Effects Of Multilayered Dielectric Spacecraft Materials: Surface Voltage, Discharge And Arcing, Gregory Wilson, Amberly Evans, Justin Dekany, Jr Dennison

Gregory Wilson

Charging of thin-film, multilayer dielectric materials subject to electron bombardment was found to evolve with time. The charging behavior was also highly dependent on the incident energy of the monoenergetic electron beams; this is driven by energy dependant processes including the electron penetration depth, electron emission, and material conductivity. The electron penetration depth is the average range to which incident electrons at a given incident energy penetrate into the material, thus defining the mean depth of an embedded charge layer. The secondary electron yield is the ratio of electrons emitted from the surface to the number of incident electrons; this …

Ultrahigh Vacuum Cryostat System For Extended Low Temperature Space Environment Testing, Justin Dekany, Robert H. Johnson, Gregory Wilson, Amberly Evans, Jr Dennison

Justin Dekany

The range of temperature measurements have been significantly extended for an existing space environment simulation test chamber used in the study of electron emission, sample charging and discharge, electrostatic discharge and arcing, electron transport, and luminescence of spacecraft materials. This was accomplished by incorporating a new cryostat system and sample mount, which maintained compatibility with an existing ultrahigh vacuum chamber (base pressure

The new two-stage, closed-cycle helium cryostat has an extended sample temperature range from450 K, with long-term controlled stability of

The new capabilities in this chamber have been employed to study the temperature dependence of materials properties critical to …

Electron Transport Models And Precision Measurements In A Constant Voltage Chamber, Justin Dekany, Alec Sim, Jerilyn Brunson, Jr Dennison

Justin Dekany

The conductivity of the material is a key transport parameter in spacecraft charging that determines how deposited charge will redistribute throughout the system, how rapidly charge imbalances will dissipate, and what equilibrium potential will be established under given environmental conditions. As the requirements for space missions extend to new regions of space and more stringent requirements are placed on spacecraft performance, it becomes necessary to better understand the underlying conduction mechanisms that determine the dynamic response of insulators to temperature, electric field dose rate, and sample conditioning and history. This study performed detailed measurements of the transient conductivity of representative …