Design of high-resolution flow sensor used in cold gas micro propulsion system

2021 ◽  
pp. 2140018
Author(s):  
Xiaocheng Zhu ◽  
Yan Chen ◽  
Huang Lin ◽  
Bin Guo ◽  
Xiaoliang Guo ◽  
...  
Keyword(s):  
High Resolution ◽  
High Sensitivity ◽  
Simulation Method ◽  
Low Noise ◽  
Flow Sensor ◽  
Orbit Control ◽  
Thermal Flow Sensor ◽  
Fine Control ◽  
Micro Propulsion ◽  
Cold Gas

Cold Gas Micro Propulsion (CGMP) is a reliable technology for spacecraft attitude and orbit control used in drag-free control system to compensate the environmental disturbance from the aerospace. The CGMP requiring a very fine control resolution and low noise is desired to be used on TAIJI mission for gravitational wave detection which is supported by Chinese Academy of Science (CAS). One of CGMP’s key technologies is high-resolution Gas Mass Flow Sensor (GMFS). In this paper, calorimetric thermal flow sensor characterized with miniaturization, high sensitivity and low noise is studied by simulation method and manufacturing process. By simulating the influence of heating power, electrode distance, temperature, etc. on sensor response, the methods on optimizing sensitivity and accuracy have been proposed. The sensitivity is about 2.53 mV/(m/s)/mW. An amplifier circuit with ultra-low noise of 7.29 nV/[Formula: see text]Hz for reading out has been designed, which is essential for high resolution. The sensor was fabricated and preliminary tests have been conducted. The sensitivity of the sensor is about 100 mV/(m/s).

The Properties and Use of a Computer Interfaced Video System for High Resolution Microscopy

1975 ◽  
Vol 33 ◽  
pp. 124-125
Author(s):  
William Goldfarb ◽  
Benjamin M. Siegel
Keyword(s):  
High Resolution ◽  
High Sensitivity ◽  
Low Noise ◽  
Photographic Emulsion ◽  
Signal To Noise ◽  
Computer Data ◽  
Video System ◽  
Noise Characteristics ◽  
Transmission Electron ◽  
Image Collection

Image collection from a transmission electron microscope operating at UHV throughout the column offers special problems and opportunities. Since photographic emulsion is excluded as the primary detector of electrons, a high resolution low noise slow scan video system directly interfaced to a minicomputer with disk and tape storage has been designed to do the job. The functions envisioned for the microscope requires high sensitivity, Dqe, and signal-to-noise ratio from the image collection system. Television for transmission electron microscopy has been a commercial reality for years but standard systems have resolution and signal-to-noise characteristics too limited for our application. Also, the normal TV scan rate excludes efficient computer data collection.

Design of a MEMS Temperature Difference Suspended Structure Gas Flowmeter

2012 ◽  
Vol 268-270 ◽  
pp. 1548-1552
Author(s):  
Hui Li
Keyword(s):  
High Resolution ◽  
Low Cost ◽  
High Sensitivity ◽  
Low Noise ◽  
Signal Acquisition ◽  
Guard Ring ◽  
Weak Signal ◽  
Mems Sensor ◽  
Offset Voltage ◽  
Suspended Structure

A micro flowmeter was designed based on MEMS sensor and weak signal acquisition technique. The MEMS sensor adopted VO2 thermal resistor suspended structure, which has good heat isolation performance and high sensitivity. The flow channel was made up of SU-8 gum, and this technology is simple and suitable for batch production because of low cost. The following weak signal acquisition module used super low bias current operational amplifier, aided with Guard ring protection, and 24 bit high resolution ADC to realize high resolution, low noise data acquisition through reasonable layout and ground design. The experiment shows that the entire flowmeter has favorable linearity and sensitivity in the velocity range from 0 to 30mL/min at a certain suitable offset voltage. So it can satisfy the applications in the fields such as biochemical detection, medicine and so on.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

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