The description of an experimental setup is presented, which allows the generation of high-frequency and microwave discharges for creating plasma streams in a wide range of operating parameters. Experiments on the generation of these discharges are described. Numerical modeling of the spatial distribution of electromagnetic fields that ensure the discharge sustainment under conditions corresponding to the actual parameters of the existing design and setup has been performed. Calculations of the absorption coefficients for waves at working frequency made it possible to determine the localization of absorption regions of the discharge and estimate the efficiency of the power introduced into the discharge for given discharge initiation techniques. The plasma parameters (the electron temperature and concentration) were obtained experimentally, and their dependences on the initial values of the pressure and power of electromagnetic field deposited into the discharge are presented. In the region of the placement of biopolymer samples, the parameters of the ion component of the plasma flow were determined. The results of the pilot studies on the influence of plasma on the physical and chemical properties of biopolymer samples are presented.
A compact time-of-flight neutron spectrometer was developed to study the production of neutrons at large angles in the energy range of 1–200 MeV. This spectrometer is a part of the BM@N facility at the extracted heavy ion beam of the Nuclotron accelerator at JINR. Stilbene-based detectors with silicon photomultipliers are used for the neutron registration. The main features of the spectrometer are high time resolution, short flight path, complete suppression of gamma-ray background using pulse shape discrimination, operation in a strong magnetic field, and event-by-event recording of digital data. The spectrometer’s characteristics were studied in an experiment with a beam of xenon nuclei at the energy of 3.8 A GeV.
The design of the MEPhIST-0 tokamak microwave interferometer and its system of data acquisition and processing are described. Examples of the time evolution of the linear electron density in MEPhIST-0 discharges are presented. The use of a phasemeter based on AD8302 detectors and digital post-processing of interferometer signals is compared. The beam refraction in the MEPhIST-0 chamber has been calculated. The possibility of plasma probing with a microwave interferometer for single- and two-pass configurations has been evaluated. It is shown that the transition to single-pass plasma probing allows the upper limit of the measured density to be significantly expanded (up to n0 = 3 × 1019 m−3).
In magnetic confinement nuclear fusion research, precise measurement of plasma radiative power is fundamental to understanding energy balance, physics of transportation, and ensuring safe device operation. This paper presentsmulti-channel integrated electronics, featuring an FPGA as the main controller and GbE communication, designed for metal foil detector with both positive and negative response channels for bolometer diagnostic. In this electronics design, compared to the single-channel electronics prototype developed recently, the phase shift circuit is optimized, DDS is adopted to generate carrier reference signal, and dynamic range compensation circuitry is incorporated. Within the constrained chassis, it integrates eight channels, significantly enhancing channel integration compared to the original BOLOMETER electronics on EAST. Performance testing in the electronics laboratory verified that all channels of this multi-channel integrated electronics exhibit consistent carrier excitation frequencies, with thethe maximum relative amplitude error of 0.48
The article presents a dual-band S + X receiving system for a mobile VLBI station. The input frequency range is 2.2–2.6 GHz in the S-band and 8.2–9.1 GHz in the X-band. The receiving system output frequency range is 0.1–1 GHz. The paper presents the receiving system’s functional diagram and the cryogenic receiving focal unit (CRFU) layout. CRFU structure and operating principle are considered. The calculated and measured characteristics of the receiving system and CRFU are presented. The control, power-supply, and telemetry system structure, composition, and operating principle are discussed.
