RF and microwave diagnostics for compact plasma traps and possible perspectives for fusion devices

2022 ◽  
Vol 17 (01) ◽  
pp. C01050
Author(s):  
G. Torrisi ◽  
E. Naselli ◽  
L. Di Donato ◽  
G.S. Mauro ◽  
M. Mazzaglia ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Plasma Electron ◽  
Ion Sources ◽  
Rf Plasma ◽  
Radio Waves ◽  
Microwave Diagnostics ◽  
Scale Ratio ◽  
Stable Plasma ◽  
Proper Scaling ◽  
Integrated Or

Abstract Plasma diagnostics is a topic having a great impact on R&D in compact ion sources as well as in large fusion reactors. Towards this aim, non-invasive microwave diagnostics approaches, such as interferometric, polarimetric and microwave imaging profilometric techniques can allow obtaining volumetric, line-integrated or even space-resolved information about plasma electron density. Special probes can be also designed and implemented in order to characterize external and/or self-generated radio-waves in the plasmas. In particular, the design, construction and operation of a K-band microwave interferometry/polarimetry setup based on the Frequency-Modulated Continuous-Wave (FMCW) method at INFN-LNS will be described: this tool provides reliable measurements of the plasma density even in the extreme unfavorable wavelength-to-plasma scale ratio in plasma-based ion sources. A “frequency sweep” and a post-processing filtering method (for interferometry and polarimetry, respectively) were used to filter out the multipath contributions or cavity induced depolarizations in the detected signals. Besides this, the use of the aforementioned RF plasma-immersed probes will also be discussed, which allow measuring local E-fields and fast temporal response in order to characterize turbulent (through kinetic instabilities, cyclotron maser emission, etc.) vs. stable plasma regimes. An analysis based on wavelet transform applied to measurements of plasma radio self-emission in B-minimum and simple mirror traps will be presented. These tools and methods have the potential to be applied to plasma machines both in compact traps and large-size reactors with a proper scaling.

Blue Laser Diodes by Low Temperature Plasma Assisted MBE

2008 ◽  
Vol 140 ◽  
pp. 17-26 ◽  
Author(s):  
Czeslaw Skierbiszewski
Keyword(s):  
Continuous Wave ◽  
Laser Diodes ◽  
Plasma Source ◽  
Blue Laser ◽  
Rf Plasma ◽  
Threading Dislocation ◽  
Temperature Plasma ◽  
Threading Dislocation Density ◽  
Bulk Gan ◽  
New Perspective

Recent progress in the growth of nitride based semiconductor structures made by plasma assisted MBE (PAMBE) is reported. The technology is ammonia free and the nitrogen for growth is activated by an RF plasma source from nitrogen molecules. A new approach for the growth of nitrides by PAMBE at temperature range 500 - 600°C is described. The key for this technique is to use a thin, dynamically stable metal (In or Ga) layer on the (0001) GaN surface, which enables a high quality 2D step-flow growth mode to be achieved at temperatures much lower than those determined by thermodynamic considerations. A new perspective for PAMBE in optoelectronics has been opened recently by a demonstration of continuous wave operation of InGaN blue–violet laser diodes. These laser diodes were fabricated on bulk GaN substrates with a low threading dislocation density.

Ion-beam sputter deposition process for Y1Ba2Cu3O7-δ thin-film structures

1994 ◽  
Vol 9 (11) ◽  
pp. 2747-2760 ◽  
Author(s):  
J-P. Krumme ◽  
V. Doormann ◽  
F. Welz ◽  
O. Dösssel ◽  
H. van Hal
Keyword(s):  
Ion Beam ◽  
Salient Feature ◽  
Charge Compensation ◽  
Deposition Process ◽  
Plasma Electron ◽  
Ion Source ◽  
Sputter Deposition ◽  
Morphological Properties ◽  
Rf Plasma ◽  
Ion Beam Sputter Deposition

Ion-beam sputter deposition (IBS) has been developed to a fully oxygen-compatible technology for growth of complex oxides, such as Y1Ba2Cu3O7−δ (YBCO) thin films. The IBS system consists of an rf-plasma ion source with molybdenum grids for sputtering, a dc-plasma electron source for space charge compensation, stoichiometric YBCO and NGO targets, a beam chopper with BaO2, Cu, and Nd blades for stoichiometry control, and an ECR-oxygen-plasma source for in situ film oxidation and photoresist removal. Due to its complexity the IBS process is fully computer-controlled. A salient feature of IBS is the excellent crystallographic and morphological properties of thin (100)/(010)- and (103)-oriented YBCO films on SrTiO3 (STO) and NdGaO3 (NGO) substrates. Sharp interfaces and good superconducting properties render this technology feasible for the fabrication of SIS-ramp-junction SQUID's.

Continuous-Wave RF Plasma Polymerization of Furfuryl Methacrylate: Correlation Between Plasma and Surface Chemistry

2016 ◽  
Vol 14 (3) ◽  
pp. 1600054 ◽  
Author(s):  
Solmaz Saboohi ◽  
Sameer A. Al-Bataineh ◽  
Hanieh Safizadeh Shirazi ◽  
Andrew Michelmore ◽  
Jason D. Whittle
Keyword(s):  
Surface Chemistry ◽  
Plasma Polymerization ◽  
Continuous Wave ◽  
Rf Plasma

Thin Film Plasma Deposition of Allylamine; Effects of Solvent Treatment

1998 ◽  
Vol 544 ◽  
Author(s):  
M. T. van Os ◽  
B. Menges ◽  
R. Förch ◽  
W. Knoll ◽  
R. B. Timmons ◽  
...  
Keyword(s):  
Film Thickness ◽  
Photoelectron Spectroscopy ◽  
Continuous Wave ◽  
Plasma Deposition ◽  
Rf Plasma ◽  
Pulsed Plasma ◽  
Grafting Reactions ◽  
Simultaneous Study ◽  
Drying Behaviour ◽  
Mode Spectroscopy

AbstractAmine-functionalized thin films were prepared by plasma induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed plasma conditions to control the film chemistry, all other process variables being held constant. Using plasma polymerized films for subsequent grafting reactions or for direct biomedical applications usually involves exposure of the films to a solvent environment. It was the major focus of this work to investigate both the chemical and physical effects of solvents on plasma polymerized allylamine films. Film properties were determined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Waveguide Mode Spectroscopy (WaMS) and Surface Plasmon Spectroscopy (SPS). WaMS provided an ideal opportunity to study the complex swelling and drying behaviour of these films by allowing a simultaneous study of the changes in film thickness and refractive index. Although the amine groups of the monomer were increasingly retained in the films as the RF duty cycle was lowered, a larger amount of oxygen was also found to be incorporated upon exposure to air. Extraction in ethanol led to a decrease in film thickness, especially for the films produced at low duty cycles, but appeared to have little effect on the film composition, as measured by XPS and FTIR.

scholarly journals Modelling RF-plasma interaction in ECR ion sources

2017 ◽  
Vol 157 ◽  
pp. 03054
Author(s):  
David Mascali ◽  
Giuseppe Torrisi ◽  
Alessio Galatà ◽  
Gino Sorbello ◽  
Giuseppe Castro ◽  
...  
Keyword(s):  
Ion Sources ◽  
Rf Plasma ◽  
Plasma Interaction

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

Microstructures of Laser Processed Fe-Cr Surface Alloys

1981 ◽  
Vol 39 ◽  
pp. 328-329
Author(s):  
P. A. Molian ◽  
K. H. Khan ◽  
W. E. Wood
Keyword(s):  
Cooling Rate ◽  
Pure Iron ◽  
Continuous Wave ◽  
Laser Surface ◽  
Material Surface ◽  
Constitution Diagram ◽  
Incident Power ◽  
Surface Alloying ◽  
Laser Surface Alloying ◽  
Spot Diameter

In recent years, the effects of chromium on the transformation characteristics of pure iron and the structures produced thereby have been extensively studied as a function of cooling rate. In this paper, we present TEM observations made on specimens of Fe-10% Cr and Fe-20% Cr alloys produced through laser surface alloying process with an estimated cooling rate of 8.8 x 104°C/sec. These two chromium levels were selected in order to study their phase transformation characteristics which are dissimilar in the two cases as predicted by the constitution diagram. Pure iron (C<0.01%, Si<0.01%, Mn<0.01%, S=0.003%, P=0.008%) was electrodeposited with chromium to the thicknesses of 40 and 70μm and then vacuum degassed at 400°F to remove the hydrogen formed during electroplating. Laser surface alloying of chromium into the iron substrate was then performed employing a continuous wave CO2 laser operated at an incident power of 1200 watts. The laser beam, defocussed to a spot diameter of 0.25mm, scanned the material surface at a rate of 30mm/sec, (70 ipm).

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