High dynamic range measurement of CdWO4 afterglow Postupaev, V.V.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Volume:
923
Journal Article
Peer reviewed
The notable feature of cadmium tungstate (CWO) is quite long (∼14.5μs) decay time of its brightest scintillation component. In this paper, the technique and results of high dynamic range measurements ...of CWO afterglow are discussed. Samples were irradiated by bremsstrahlung of a ∼0.5 MeV, 6μs electron beam. The afterglow tail of the scintillation curve was measured down to the relative amplitude <10−5. At such intensities, a parasitic fluorescence of a photomultiplier essentially contributes to the total signal. The CWO light emission dynamics is determined by known scintillation components to at least 10−5 level. Constraints on the existence of a possible slower fluorescence component are discussed.
•High dynamic range measurements of CdWO4 afterglow are presented.•Samples were irradiated by the bremsstrahlung of a ∼0.5 MeV, 6μs electron beam.•The exponential decay of CdWO4 scintillation continues to at least to 10−5 level.•Observed afterglow tail attributed to the excitation of the photomultiplier elements.•Constraints for a possible long-living fluorescence component are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This review is focused on multiple-mirror traps for high-temperature plasma confinement that were proposed by Budker, Mirnov, and Ryutov and independently by Logan, Lichtenberg, and Lieberman in the ...early 1970s. The proposed magnetic system solved problems with the kinetic instabilities of classical open traps and significantly increased the plasma life-time. We review the history of this field and discuss its achievements and prospects.
Results, obtained during the last decade on linear traps in Novosibirsk, verified the original concepts and led to discovery of new ways of plasma confinement in linear traps. It turns out that the ...multiple-mirror confinement, once thought to be suitable for pulsed fusion only, can work in tandem with gas-dynamic traps. Its helical-mirror variant can provide additional advantages for confinement of rotating plasmas such as radial and axial plasma pinch fluxes. The specially designed gas-dynamic mirrors can be run in the high-β “diamagnetic” regime, closely resembling the field-reversed configurations both in shape and in the quality of axial confinement. These new ideas form the groundwork of the possible road for linear traps to fusion.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
4.
Gas-Dynamic Multiple-Mirror Trap GDMT Skovorodin, D. I.; Chernoshtanov, I. S.; Amirov, V. Kh ...
Plasma physics reports,
09/2023, Volume:
49, Issue:
9
Journal Article
Peer reviewed
This work is devoted to the project of a new-generation open trap, gas-dynamic multiple-mirror trap (GDMT), proposed at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of ...Sciences. The aim of the project is to substantiate the possibility of using open traps as thermonuclear systems: a source of neutrons and, in the future, a thermonuclear reactor. The main objectives of the project are to develop technologies for long-term plasma maintenance in an open trap, optimize neutron source parameters based on the gas-dynamic trap, and demonstrate methods for improving plasma confinement. The magnetic vacuum system of the facility consists of a central trap, multiple-mirror sections that improve the longitudinal plasma confinement, and expanders designed to accommodate plasma flux absorbers. The facility is to be built in several stages. The starting configuration is broadly similar to the GDT facility and includes a central trap with strong magnetic mirrors and expanders. It solves two main problems: optimization of the parameters of the neutron source based on the gas-dynamic trap and study of the physics of the transition to the configuration of a diamagnetic trap with a high relative pressure β ≈ 1, which significantly increases the efficiency of the system. This work describes the technical design of the starting configuration of the facility and outlines the physical principles on which the GDMT project is based.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper presents experimental results from the SMOLA device on the testing of the helical mirror confinement hypothesis. Helical mirror confinement is the technique of an active control of axial ...plasma losses from a confinement zone by multiple magnetic mirrors that move along the axis in the reference frame of the plasma that experiences $\boldsymbol{E} \times \boldsymbol{B}$ rotation due to an applied radial electric field. Theory predicts that a helical mirror will provide an axial force that modifies the plasma flow and, simultaneously, density pinching to the axis. The force direction depends on the plasma rotation direction. Experimental data on the axial plasma losses at different direction of the magnetic mirror movement are presented. If the trapped ions move in the direction opposite to the direction of the axial losses, then the particle flux reduces in the broad range of the plasma density. The confinement improves with the increase of the fraction of the trapped particles (effective mirror ratio was up to $R_{{\rm eff}}=5.8\pm 1.4$). If the trapped ions move in the same direction as the axial losses, then the flux depends on density. At intermediate densities, the integral flux through the transport section rises compared to the plasma flowing through the straight magnetic field. The effective mirror ratio is lower and does not significantly depend on the fraction of the trapped particles (effective mirror ratio at intermediate density was $R_{{\rm eff}}=3.3\pm 0.8$).
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•The recently-suggested helical mirror confinement concept is discussed.•Active suppression of axial particle and energy losses.•Parameter space for the first experiment is ...discussed.•Details of magnetic system of the SMOLA project are presented.
A novel concept of helical mirror confinement with active axial and radial plasma flow control is discussed. The idea relies on the retarding force that appears when biased plasma experiences rotation in crossed electrical and helical mirror magnetic fields. Preparations for its experimental study started in Budker Institute of Nuclear Physics, Novosibirsk. Possible parameter space for a concept-exploration-class device SMOLA is identified. Details of numerical optimization of the magnetic structure of the device are presented. The main physical task for the SMOLA experiment will be direct demonstration of the helical mirror performance in simple experimental conditions at reasonably low plasma parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
A system of four-electrode Langmuir probes developed for the GOL-NB multiple-mirror trap is discussed. The system is used for studies of a low-temperature start plasma (10
19
–10
20
m
-3
, 5 ...eV) that fills the device during the initial phase of the experiment. The probe allows simultaneous measurements of plasma density, electron temperature and radial electric field. The accuracy of the probe measurements is also discussed.
The paper presents experimental investigations of tungsten surface modification after plasma loads at the multimirror trap GOL-3. Energy loads on tungsten surface varied from 2 up to 4MJ/m2 per shot ...with sets from 1 to 9 repetitive irradiations that corresponds to loads higher than tungsten melting threshold and is close to ITER giant ELM loads.
Targets surface modification and transverse microsections after irradiation was studied by optical microscopy, SEM and hardness tester. Formation on tungsten surface of three different crack networks with typical cell sizes of 1000, 10 and 0.3μm and bubbles are identified. The network of large cracks extend perpendicularly to the irradiated sample surface to a depth of 50–350μm. Erosion depth depends on energy loads – rises from 20 to 200μm at 2 and 4MJ/m2 correspondingly. Cracking, development of tungsten surface morphology and droplets splashing are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The results on applying the technique of vortex plasma confinement in the GOL-NB facility are presented. The first experiments on optimizing the biasing the in-chamber electrodes demonstrated an ...improvement in the dynamics of trapping the injected fast hydrogen atoms, as well as a decrease in the fluctuations of local plasma parameters in the central trap and an increase in the plasma decay time. The geometry of in-chamber electrodes arrangement, as well as the polarity and magnitude of the supplied potentials, correspond to the theory of vortex confinement and to those in similar studies at other open traps.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The physics of confinement of plasma rotating in the magnetic field with linear helical symmetry is studied at the SMOLA open trap at Budker Institute of Nuclear Physics of the Siberian Branch of the ...Russian Academy of Sciences. The factor characterizing the quality of plasma confinement in the system is its flow velocity. The paper describes the diagnostics applied, which is based on the Mach probe used under the conditions of nonmagnetized plasma; this diagnostics made it possible to determine the longitudinal flow velocity in the experiments. In different operating regimes of the device, the measured longitudinal flow velocity was (0.5−5) × 10
6
cm/s. It is discussed how the velocity depends on the magnetic field corrugation. The reverse flow of trapped particles returning to the confinement zone was detected.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
