Plasma properties measurements of parallel-plane electrodes in argon by coupling OES and PLIF

2021 ◽  
Author(s):  
Fangyi Wang ◽  
Shaohua Zhang ◽  
Xilong Yu
Keyword(s):  
Parallel Plane ◽  
Plasma Properties

Unbiased estimation of particle number and sizes using the new stereological tools: the disector, the fractionator, the selector, and the nucleator — or just point-sampled intercepts

1988 ◽  
Vol 46 ◽  
pp. 428-429
Author(s):  
H.J.G. Gundersen
Keyword(s):  
Particle Number ◽  
Small Distance ◽  
Parallel Plane ◽  
Unbiased Estimation ◽  
Severe Problem ◽  
New Era ◽  
Size And Shape ◽  
Distinct Property ◽  
Sectioned Tissue

Previously, all stereological estimation of particle number and sizes were based on models and notoriously gave biased results, were very inefficient to use and difficult to justify. For all references to old methods and a direct comparison with unbiased methods see recent reviews.The publication in 1984 of the DISECTOR, the first unbiased stereological probe for sampling and counting 3—D objects irrespective of their size and shape, signalled the new era in stereology — and give rise to a number of remarkably simple and efficient techniques based on its distinct property: It is the only known way to obtain an unbiased sample of 3-D objects (cells, organelles, etc). The principle is simple: within a 2-D unbiased frame count or sample only cells which are not hit by a parallel plane at a known, small distance h.The area of the frame and h must be known, which might sometimes in itself be a problem, albeit usually a small one. A more severe problem may arise because these constants are known at the scale of the fixed, embedded and sectioned tissue which is often shrunken considerably.

Plasma properties

1992 ◽  
Author(s):  
H. Weitzner
Keyword(s):  
Plasma Properties

COMPARISON OF ELECTRON BEAM TRANSMISSION OF DIFFERENT ENERGIES WITH TWO DIFFERENT BLOCK MATERIALS AT DIFFERENT PLACEMENT POSITIONS WITHIN THE APPLICATOR

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Navitha M ◽  
Jitendra Nigam ◽  
Silambarasan N S ◽  
Piyush Kumar ◽  
Pavan Kumar
Keyword(s):  
Electron Beam ◽  
Skin Surface ◽  
Parallel Plane ◽  
Percentage Transmission ◽  
Upper Level ◽  
Beam Transmission ◽  
Shielding Material ◽  
Different Thickness ◽  
Thick Lead ◽  
Lead Sheet

INTRODUCTION: Superficial tumors are treated with electron beams. Shielding blocks are used to conform to the shape of the tumor. These shielding blocks are usually kept at lower level of the applicator which is near the skin surface. The scattering property of electron may increase the surface dose which will increase with increasing electron energies. The purpose of this study is to compare electron beam transmission of different energies with two different block materials at different placement positions within the applicator. MATERIAL AND METHODS: Cerrobend alloy (50%bismuth, 26.7%lead, 13.3%tin and 10%cadmium) and 1mm thick lead sheets (94%lead, 6%alloy) in Varian Clinac2300C/D linear accelerator with electron energies 6,9,12,16 and 20MeVs using 10x10 applicator at 3 different holding levels was used. Measurements with RW3 Slab phantom (Water equivalent), PPC05 Parallel Plane Chamber, Dose 1 electrometer was done. The slab phantom 30x30x10 cm3 aligned with PPC05 Parallel Plane Chamber (at R85 of respective energies). Readings measured for open and block fields, for different thickness of shielding material, at different placement positions within the applicator. The percentage transmission calculated manually. RESULTS: Using electron energies 6,9,12,16, and 20MeVs respectively the transmission% were: with lead sheet 1mm thickness-2.48%,8.69%,16.05%, 28.03% and 39.50% at lower placement position, 1.19%,3.76%,7.75%,15% and 23.99% at centre placement and 0.96%,3.02%,6.15% and 20.27% for upper placement; with 2mm thickness-0.89%,1.62%,3.66%, 8.95% and 16.35% at lower level, 0.60%,1.28%,2.54%,5.74% and 10.72% at centre level and 0.57%,0.94%, 2.12%,4.85% and 9.22% at upper level; with 3mm thickness-0.80%,1.53%,2.88%,5.29% and 9.42% at lower position, 0.52%,1.25%,2.06%,4.03% and 7.36% at centre position and 0.51%, 0.90%,1.78%,3.66% and 6.43% at upper position; with 4mm thickness- 0.75%,1.40%, 2.71%,4.81% and 7.76% at lower level, 0.50%,1.18%,1.95%,3.68% and 6.31% at center level and 0.51%,0.80%, 1.70%,3.34% and 5.65% at upper level; with 5mm thickness-0.73%, 1.30%,2.57%,4.56% and 7.20% at lower level, 0.45%,1.06%,1.81%,3.48% and 5.68% at center level and 0.47%,0.79%,1.61%,3.13% and 5.24% at upper level. For Cerrobend material 5mm thickness, the transmission at lower level are 0.79%,1.50%,2.98%,5.58% and 10.39%, at center level are 0.52%,0.99%,2.09%,4.12% and 7.67% and at upper level are 0.49%,0.91%, 1.82%,3.75% and 6.90% for the energies 6,9,12,16 and 20 MeV’s respectively. CONCLUSION: There is not much difference in the transmission values at centre and upper levels so as to keep nearer the skin, the centre position in electron applicator may be optimum. Lead sheets can be used since easy to prepare especially for rectangular or square shapes.

Long-pulse plasma source for SMOLA helical mirror

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Ivan A. Ivanov ◽  
V. O. Ustyuzhanin ◽  
A. V. Sudnikov ◽  
A. Inzhevatkina
Keyword(s):  
Magnetic Field ◽  
Gas Flow ◽  
Supply Voltage ◽  
Hydrogen Plasma ◽  
Plasma Source ◽  
Lanthanum Hexaboride ◽  
Plasma Stream ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Plasma Gun

A plasma gun for forming a plasma stream in the open magnetic mirror trap with additional helicoidal field SMOLA is described. The plasma gun is an axisymmetric system with a planar circular hot cathode based on lanthanum hexaboride and a hollow copper anode. The two planar coils are located around the plasma source and create a magnetic field of up to 200 mT. The magnetic field forms the magnetron configuration of the discharge and provides a radial electric insulation. The source typically operates with a discharge current of up to 350 A in hydrogen. Plasma parameters in the SMOLA device are Ti ~ 5 eV, Te ~ 5–40 eV and ni ~ (0.1–1)  × 1019 m−3. Helium plasma can also be created. The plasma properties depend on the whole group of initial technical parameters: the cathode temperature, the feeding gas flow, the anode-cathode supply voltage and the magnitude of the cathode magnetic insulation.

scholarly journals Numerical and Experimental Investigation of Longitudinal Oscillations in Hall Thrusters

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 148
Author(s):  
Vittorio Giannetti ◽  
Manuel Martín Saravia ◽  
Luca Leporini ◽  
Simone Camarri ◽  
Tommaso Andreussi
Keyword(s):  
Discharge Current ◽  
Fluid Model ◽  
Low Frequency ◽  
Hall Thruster ◽  
Hall Thrusters ◽  
Current Signal ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Breathing Mode ◽  
Spatio Temporal

One of the main oscillatory modes found ubiquitously in Hall thrusters is the so-called breathing mode. This is recognized as a relatively low-frequency (10–30 kHz), longitudinal oscillation of the discharge current and plasma parameters. In this paper, we present a synergic experimental and numerical investigation of the breathing mode in a 5 kW-class Hall thruster. To this aim, we propose the use of an informed 1D fully-fluid model to provide augmented data with respect to available experimental measurements. The experimental data consists of two datasets, i.e., the discharge current signal and the local near-plume plasma properties measured at high-frequency with a fast-diving triple Langmuir probe. The model is calibrated on the discharge current signal and its accuracy is assessed by comparing predictions against the available measurements of the near-plume plasma properties. It is shown that the model can be calibrated using the discharge current signal, which is easy to measure, and that, once calibrated, it can predict with reasonable accuracy the spatio-temporal distributions of the plasma properties, which would be difficult to measure or estimate otherwise. Finally, we describe how the augmented data obtained through the combination of experiments and calibrated model can provide insight into the breathing mode oscillations and the evolution of plasma properties.

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