Performance of 30 cm Pyrolytic-Graphite Ion Thruster Optics

2003 ◽  
Author(s):  
Thomas Haag ◽  
George Soulas
Keyword(s):  
Pyrolytic Graphite ◽  
Ion Thruster

The impact of neutralizer-free ignition of a radio frequency ion thruster on the lifetime of the ion optics system

2021 ◽  
pp. 2140017
Author(s):  
Long-Fei Ma ◽  
Li Duan ◽  
Jian-Wu He ◽  
Qi Kang ◽  
Keyword(s):  
Radio Frequency ◽  
Pyrolytic Graphite ◽  
High Strength ◽  
Surface Damage ◽  
External Source ◽  
Ion Thruster ◽  
Neutral Gas ◽  
Discharge Ignition ◽  
Ion Optical System ◽  
The Impact

In the initial stage of a radio frequency ion thruster (RIT) ignition, an influx of electrons is required from an external source into the discharge chamber and ionization of the neutral gas propellant. A neutralizer-free method for Townsend breakdown discharge ignition based on Paschen’s law was developed in this study. The feasibility of the ignition method was confirmed by performing thousands of ignition experiments. Metallic Molybdenum (Mo), pyrolytic graphite (PG) and Zr[Formula: see text]Ti[Formula: see text]Cu[Formula: see text]Ni[Formula: see text]Be[Formula: see text]alloy acceleration grids were prepared, and ignition-induced damage on the grids was investigated. A field-emission scanning electron microscope was used to inspect surface damage on the grids after multiple ignitions and to analyze the influence of the ignition method on the lifetime of the ion optical system. Grid materials for space missions that require multiple RIT ignitions (10[Formula: see text] should be high-strength blocks that are resistant to sputtering corrosion and high temperature.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

Comparison of TEM and STM observations of small silver clusters on different carbon supports

1990 ◽  
Vol 48 (4) ◽  
pp. 264-265
Author(s):  
Bernd Tesche ◽  
Tobias Schilling
Keyword(s):  
Vibration Isolation ◽  
Pyrolytic Graphite ◽  
Carbon Film ◽  
Silver Clusters ◽  
Carbon Supports ◽  
Stacking Order ◽  
System P ◽  
High Resolution Tem ◽  
High Degree ◽  
Degree Of Order

The objective of our work is to determine:a) whether both of the imaging methods (TEM, STM) yield comparable data andb) which method is better suited for a reliable structure analysis of microclusters smaller than 1.5 nm, where a deviation of the bulk structure is expected.The silver was evaporated in a bell-jar system (p 10−5 pa) and deposited onto a 6 nm thick amorphous carbon film and a freshly cleaved highly oriented pyrolytic graphite (HOPG).The average deposited Ag thickness is 0.1 nm, controlled by a quartz crystal microbalance at a deposition rate of 0.02 nm/sec. The high resolution TEM investigations (100 kV) were executed by a hollow-cone illumination (HCI). For the STM investigations a commercial STM was used. With special vibration isolation we achieved a resolution of 0.06 nm (inserted diffraction image in Fig. 1c). The carbon film shows the remarkable reduction in noise by using HCI (Fig. 1a). The HOPG substrate (Fig. 1b), cleaved in sheets thinner than 30 nm for the TEM investigations, shows the typical arrangement of a nearly perfect stacking order and varying degrees of rotational disorder (i.e. artificial single crystals). The STM image (Fig. 1c) demonstrates the high degree of order in HOPG with atomic resolution.

Experimental Sensitivity Analysis of Operational Points of the Microwave-discharge Miniature Ion Thruster

2019 ◽  
Vol 67 (3) ◽  
pp. 74-80
Author(s):  
Yuichi Nakagawa ◽  
Mirai Iida ◽  
Taishi Yoshitake ◽  
Hiroyuki Koizumi ◽  
Kimiya Komurasaki
Keyword(s):  
Sensitivity Analysis ◽  
Microwave Discharge ◽  
Ion Thruster

A 30 cm mercury ion thruster module

1970 ◽  
Author(s):  
H. KING ◽  
R. POESCHEL
Keyword(s):  
Mercury Ion ◽  
Ion Thruster

A north-south stationkeeping ion thruster system for ATS-F

1973 ◽  
Author(s):  
E. JAMES ◽  
W. RAMSEY ◽  
G. GANT ◽  
L. JAN ◽  
R. BARTLETT
Keyword(s):  
Ion Thruster
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