Dust impact detections by a set of Faraday cups in the lunar environments

2020 ◽  
Author(s):  
Oleksii Kononov ◽  
Jiří Pavlů ◽  
Libor Nouzák ◽  
Jana Šafránková ◽  
Zdeněk Němeček ◽  
...  
Keyword(s):  
Solar Wind ◽  
Sampling Rate ◽  
Identification Algorithm ◽  
Impact Pulse ◽  
Ion Energy ◽  
Ion Energy Distribution ◽  
Hypervelocity Impacts ◽  
Dust Detection ◽  
The Impact ◽  
Novel Design

<p>The Bright Monitor of the Solar Wind (BMSW) for the Luna-Resurs-1 mission is an instrument designed for high-time (30 ms) resolution measurements of moments of the ion energy distribution by Faraday cups in the solar wind and in a plasma environment at altitudes between 65 and 150 km above the lunar surface. Previous studies performed by a similar instrument located on-board the Spektr-R spacecraft demonstrated a possibility to detect hypervelocity impacts of dust grains by such instruments Our analysis shows that the main problem of the reliable detection of dust impacts using such types of instruments is their sampling rate. In the paper, we present a novel design of a set of FCs that improves the ability of the dust detection using a simple identification algorithm that can store data with a higher sampling rate around the impact pulse. Moreover, we discuss a calibration of the detectors and their front-end electronics using the dust accelerator in order to find a relation between impact parameters and pulse heights.</p>

Dust detection by antenna instruments

2020 ◽  
Author(s):  
Zoltan Sternovsky ◽  
Ming-Hsueh Shen ◽  
Michael DeLuca ◽  
Åshild Fredriksen ◽  
Mihály Horányi ◽  
...  
Keyword(s):  
Sampling Rate ◽  
Laboratory Data ◽  
Quantitative Description ◽  
High Rate ◽  
Dust Particles ◽  
Electric Signal ◽  
Accelerator Facility ◽  
Spacecraft Potential ◽  
Dust Detection ◽  
The Impact

<p>Antenna instruments on space missions have been used to detect dust particles and characterize dust populations. The antennas register the transient electric signal generated by the expansion of the impact plasma from the dust impact on the spacecraft body or the antenna. Given the large effective sensitive area, antenna instruments offer an advantage over dedicated dust detectors for dust populations with low fluxes. The dust accelerator facility operated at the University of Colorado has been employed to investigate the physical mechanisms of antenna signal generation. The dominant mechanism is related to the charging of the spacecraft (or antenna) by collecting some fraction of electrons and ions from the impact plasma. We have carried out a number of experimental campaigns in order to characterize the dust impact charge yields from relevant materials, the effective temperatures of dust impact plasmas, and variations of the antenna signals with spacecraft potential, or magnetic field. Here we report on a physical model that provides a good qualitative and quantitative description of the antenna waveforms recorded in laboratory conditions. The model is based on the separation of the electrons from the ions in the impact plasma and their different timescales of expansion. The escaping and collected fractions of charges are driven by the spacecraft potential. Fitting the model to the laboratory data revealed that the electrons in the impact plasma have an isotropic distribution, while ions are dominantly moving away from the dust impact location. Identifying the fine details in the antenna signals requires a relatively high sampling rate and thus not commonly resolved for past instruments. The high-rate mode of the FIELDS instrument on the Parker Solar Probe, however, can be used to verify the proposed model.</p>

The impact of frequency mixing on sheath properties: Ion energy distribution and Vdc∕Vrf interaction

2005 ◽  
Vol 97 (10) ◽  
pp. 103304 ◽  
Author(s):  
Steven Shannon ◽  
Daniel Hoffman ◽  
Jang-Gyoo Yang ◽  
Alex Paterson ◽  
John Holland
Keyword(s):  
Energy Distribution ◽  
Ion Energy ◽  
Ion Energy Distribution ◽  
The Impact ◽  
Frequency Mixing

Embracing Collisions to Increase Fidelity of Sensing Systems with COTS Tags

2021 ◽  
Vol 5 (2) ◽  
pp. 1-20
Author(s):  
Jiaqi Xu ◽  
Wei Sun ◽  
Kannan Srinivasan
Keyword(s):  
Low Cost ◽  
Sampling Rate ◽  
Identification Algorithm ◽  
Current Standard ◽  
Tag Identification ◽  
Rfid Systems ◽  
Passive Tags ◽  
Sensing Systems ◽  
Channel Diversity ◽  
Channel Information

RFID techniques have been extensively used in sensing systems due to their low cost. However, limited by the structural simplicity, collision is one key issue which is inevitable in RFID systems, thus limiting the accuracy and scalability of such sensing systems. Existing anti-collision techniques try to enable parallel decoding without sensing based applications in mind, which can not operate on COTS RFID systems. To address the issue, we propose COFFEE, which enables parallel channel estimation of COTS passive tags by harnessing the collision. We revisit the physical layer design of current standard. By exploiting the characteristics of low sampling rate and channel diversity of RFID tags, we separate the collided data and extract the channels of the collided tags. We also propose a tag identification algorithm which explores history channel information and identify the tags without decoding. COFFEE is compatible with current COTS RFID standards which can be applied to all RFID-based sensing systems without any modification on tag side. To evaluate the real world performance of our system, we build a prototype and conduct extensive experiments. The experimental results show that we can achieve up to 7.33x median time resolution gain for the best case and 3.42x median gain on average.

A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s

2012 ◽  
Vol 225 ◽  
pp. 275-280
Author(s):  
Chandra B. Asthana ◽  
Rama B. Bhat
Keyword(s):  
Shock Absorber ◽  
Fluid Viscosity ◽  
Simulation Approach ◽  
Body Frame ◽  
Mr Fluid ◽  
Orifice Area ◽  
Aerial Vehicle ◽  
Impact Kinetic Energy ◽  
The Impact ◽  
Novel Design

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.

The ion energy distribution in front of a negative wall

1992 ◽  
Vol 25 (4) ◽  
pp. 620-633 ◽  
Author(s):  
K -U Reimann ◽  
U Ehlemann ◽  
K Wiesemann
Keyword(s):  
Energy Distribution ◽  
Ion Energy ◽  
Ion Energy Distribution

Molecular Dynamics Study of Ion Impact Phenomena and Compressive Stress in Thin Films

1993 ◽  
Vol 317 ◽  
Author(s):  
N.A. Marks ◽  
P. Guan ◽  
D.R. Mckenzie ◽  
B.A. PailThorpe
Keyword(s):  
Molecular Dynamics ◽  
Three Dimensional ◽  
Carbon Films ◽  
Loss Mechanism ◽  
Ion Energy ◽  
Lennard Jones ◽  
Impact Phenomena ◽  
Ion Impact ◽  
Dynamics Simulations ◽  
The Impact

ABSTRACTMolecular dynamics simulations of nickel and carbon have been used to study the phenomena due to ion impact. The nickel and carbon interactions were described using the Lennard-Jones and Stillinger-Weber potentials respectively. The phenomena occurring after the impact of 100 e V to 1 keV ions were studied in the nickel simulations, which were both two and three-dimensional. Supersonic focussed collision sequences (or focusons) were observed, and associated with these focusons were unexpected sonic bow waves, which were a major energy loss mechanism for the focuson. A number of 2D carbon films were grown and the stress in the films as a function of incident ion energy was Measured. With increasing energy the stress changed from tensile to compressive and reached a maximum around 50 eV, in agreement with experiment.

Ion Energy Distribution Skew Control Using Phase-Locked Harmonic RF Bias Drive

2014 ◽  
Vol 42 (7) ◽  
pp. 1880-1893 ◽  
Author(s):  
David J. Coumou ◽  
David Hamilton Clark ◽  
Theresa Kummerer ◽  
Michael Hopkins ◽  
Donal Sullivan ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Ion Energy ◽  
Ion Energy Distribution
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