Various versions of an extraction system for a helicon ion source have been investigated in high plasma density (>10(12) cm(-3)) modes. The measurements of the plasma density were carried out with a microwave interferometer. Experiments were performed with hydrogen and helium gases. The preliminary results indicate that specially designed extractors are very promising for improving ion beam paraxial brightness.
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http://dx.doi.org/10.1063/1.2802569 | DOI Listing |
Rev Sci Instrum
April 2024
Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India.
In the pursuit of precise diagnostics for measuring negative ion density in a helicon plasma source (HPS), a new approach utilizing a radio frequency (RF) broadband transformer-based Langmuir probe is developed specifically for laser photo-detachment (LPD) analysis. This inductively coupled LPD technique is useful for high power RF systems in which capacitive RF noise is in the same scale as the pulsed photo-detachment signal. The signal acquired by this transformer-based probe is compared against the conventional Langmuir probe-based LPD technique, revealing a remarkable enhancement in signal fidelity through an improved signal-to-noise ratio (SNR) achieved by the RF broadband transformer methodology.
View Article and Find Full Text PDFNanomaterials (Basel)
October 2023
ICP Institute of Computational Physics, ZHAW Zürich University of Applied Sciences, Wildbachstrasse 21, CH-8401 Winterthur, Switzerland.
Ion-flow-stimulated roughening transition is a phenomenon that may prove useful in the hierarchical structuring of nanostructures. In this work, we have investigated theoretically and experimentally the surface texturing of single-crystal and multi-crystalline silicon wafers irradiated using ion-beam flows. In contrast to previous studies, ions had relatively low energies, whereas flow densities were high enough to induce a quasi-liquid state in the upper silicon layers.
View Article and Find Full Text PDFRev Sci Instrum
July 2023
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
A novel quadrature Doppler Backscattering (DBS) system has been developed and optimized for the E-band (60-90 GHz) frequency range using either O-mode or X-mode polarization in DIII-D plasmas. In general, DBS measures the amplitude of density fluctuations and their velocity in the lab frame. The system can simultaneously monitor both low-frequency turbulence (f < 10 MHz) and radiofrequency plasma density fluctuations over a selectable frequency range (20-500 MHz).
View Article and Find Full Text PDFMaterials (Basel)
December 2022
Laboratory for Space Environment and Physical Sciences, Harbin Institute of Technology, Harbin 150001, China.
A steady-state, high-flux N/Ar helicon wave plasma (HWP) with a small diameter (10 mm) was used to nitride the interior of a slender austenitic stainless steel (ASS) 316L tube at a temperature of 450 °C. N and Ar were fed to a 500 mm long slender tube with 10 mm inner diameter and were ionized inside the tube using a helicon wave in the magnetic field of 2000 G. The microstructure and depth of the nitrided layers, in addition to the morphology and hardness of the nitrided surfaces, were intensively characterized by employing scanning electron microscopy (SEM), optical microscopy (OM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as microhardness tests.
View Article and Find Full Text PDFRev Sci Instrum
October 2021
Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA.
For the first time, a digital Mirror Langmuir Probe (MLP) has successfully sampled plasma temperature, ion saturation current, and floating potential together on a single probe tip in real time in a radio-frequency driven helicon linear plasma device. This is accomplished by feedback control of the bias sweep to ensure a good fit to I-V characteristics with a high frequency, high power digital amplifier, and field-programmable gate array controller. Measurements taken by the MLP were validated by a low speed I-V characteristic manually collected during static plasma conditions.
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