Impact of liquid hydrazine on a heated surface in the low pressure space environment

1983 ◽  
Author(s):  
P. BREISACHER ◽  
P. MAHADEVAN
Keyword(s):  
Heated Surface ◽  
Low Pressure ◽  
Space Environment

scholarly journals Research on Applicability of Hot-Bulb Anemometer under Low Pressure

2018 ◽  
Vol 179 ◽  
pp. 03028
Author(s):  
Li Xiyuan ◽  
Yin Xiaofang ◽  
Hou Yaqin ◽  
Gao Qinghua ◽  
Wang jing
Keyword(s):  
Heat Flux ◽  
Wind Speed ◽  
Dynamic Pressure ◽  
Extreme Environment ◽  
Low Pressure ◽  
Constant Heat Flux ◽  
Space Environment ◽  
Dimensionless Number ◽  
Mars Rover ◽  
Balance Test

In Mars and other deep space exploration missions, the planetary atmosphere makes the difference in heat transfer characteristics on the planetary surface and on-orbit environment. In order to achieve the purposes of thermal model correction and spacecraft verification in extreme environment, Mars rover needs to be tested in a simulated Mars environment including low pressure, solar heat flux, wind speed and background temperature. Thus, wind speed should be measured at multiple points in the Mars rover thermal test. In a general Mars rover thermal balance test, the requirement for wind speed control and measurement is 0-15m/s under 700Pa pressure. The current anemometer for industrial use is mainly based on the dynamic pressure, heat or ultrasound. They have a small signal and need to be recalibrated at low pressures. In this paper, a constant heat flux hot-bulb anemometer model has been built using dimensionless number analysis method, with which the anemometer response under low pressure has been calculated. A series of calibration test has been employed to verify the model in space environment chamber. The two methods above reached a similar result, which demonstrates the effectiveness of the analysis.

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

Quantitative surface damage studies by H.R.E.M.

1989 ◽  
Vol 47 ◽  
pp. 632-633
Author(s):  
S. R. Singh ◽  
H. J. Fan ◽  
L. D. Marks
Keyword(s):  
Solar Wind ◽  
Quantitative Analysis ◽  
Surface Science ◽  
Surface Damage ◽  
Space Environment ◽  
Oxygen Desorption ◽  
The Past ◽  
Diffusion Controlled ◽  
Original Observation ◽  
Substantial Interest

Since the original observation that the surfaces of materials undergo radiation damage in the electron microscope similar to that observed by more conventional surface science techniques there has been substantial interest in understanding these phenomena in more detail; for a review see. For instance, surface damage in a microscope mimics damage in the space environment due to the solar wind and electron beam lithographic operations.However, purely qualitative experiments that have been done in the past are inadequate. In addition, many experiments performed in conventional microscopes may be inaccurate. What is needed is careful quantitative analysis including comparisons of the behavior in UHV versus that in a conventional microscope. In this paper we will present results of quantitative analysis which clearly demonstrate that the phenomena of importance are diffusion controlled; more detailed presentations of the data have been published elsewhere.As an illustration of the results, Figure 1 shows a plot of the shrinkage of a single, roughly spherical particle of WO3 versus time (dose) driven by oxygen desorption from the surface.

New Director Named for NOAA's Space Environment Center

Space Weather ◽  
2006 ◽  
Vol 4 (6) ◽  
pp. n/a-n/a
Author(s):  
Mohi Kumar
Keyword(s):  
Space Environment

Low pressure improves ink jets

Nature ◽  
2005 ◽  
Author(s):  
Philip Ball
Keyword(s):  
Low Pressure
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