Results from experimental studies on the injection of high-energy neutral hydrogen beams into the plasma of the Globus-M spherical tokamak are reviewed. In the Introduction, the importance of these ...studies for implementing the controlled fusion research program and constructing the ITER tokamak is proved. Some problems related to the use of neutral beam injection in small and low-aspect-ratio tokamaks is analyzed. Results are presented from numerical simulations of the experiment by using the ASTRA transport code. It is shown that the use of neutral beam injection in the Globus-M tokamak ensures efficient ion heating and increases the plasma stored energy. The greater part of the review is devoted to the survey of experiments on the injection of 22-to 30-keV hydrogen and deuterium beams with a power of 0.4-0.8 MW into the plasma of the Globus-M spherical tokamak in a wide range of plasma currents and densities. The experimental results are analyzed and compared with the results of numerical simulations. The achievement of top plasma parameters is highlighted.
Bench tests are used to compare cleaning performance of inductively and capacitively driven radio-frequency (RF) discharges as a potential tool for in-situ maintenance of in-vessel diagnostic mirrors ...in fusion devices. The effect of erosion of hydrogenated carbon coating is studied in different processing conditions. Stainless steel (SS) mirrors have been exposed to CH
4
‒Ar and H
2
‒Ar plasmas in an RF discharge at a pressure of 10
−2
Torr with an input power of 0.5 kW at 13.6 MHz. The samples, which exhibit a slow rate of chemical erosion, become essentially erosive in both inductively and capacitively driven RF discharges. The cleaning ability of a capacitively driven RF discharge is studied in dedicated experiments with SS samples retrieved from the tokamaks T-10 and Globus-M after long-term exposure to the working and wall conditioning discharges.
ITER design has highlighted the fundamental need to monitor and deepen understanding of divertor operations. The designed Thomson scattering (TS) for the divertor leg and SOL near the X-point, has ...gained a lot from present State-of-the-Art in the diagnostics. However, hostile environment, very restricted access, and required spatial resolution, all impose severe constraints on the diagnostic design for ITER. Signal transmission from diagnostics introduces the further considerations of relative movements of the machine components. Despite the constraints it is feasible using of crossed probe and viewing beams to make measurements of the electron temperature and density profiles in outer divertor leg at the extent from the strike-point to X-point vicinity, and the LIDAR TS technique to make the electron temperature and density scan along the major radial line-of-sight at ∼0.5 m above the X-point. The interfaces for each of the subsystems are presented and discussed in the sections below.
•The results of multiphysics simulations for TS support structure in consequent design iterations are presented and discussed.•The close to final design of front diagnostic rack developed on the ...basis of simulation results and suitable to sustain all main ITER loads is presented.•The distortion of mirrors surfaces is analyzed and possible problems are indicated.•The new design of the mirror mounting system is proposed.
The support structure for divertor Thomson scattering equipment – the front diagnostic rack, which actually plays plugging role of the divertor port, should be designed to sustain the severe ITER conditions. Meeting the requirements of multifield analyses (which often contradict each other) results in an iterative design process. A number of design variants based on engineering analyses results were developed in 2011–2012. We study here the close to the final design of the diagnostic rack for consistency to electromagnetic, thermal and seismic loads. The specific ITER environment imposes a restricted list of materials and requires a careful design of optical elements to accommodate their thermal expansion. Special attention is focused on the mirror deformed shape under operating loading conditions and its effect on optical system performance, which is vital for all optical systems with mirrors specially designed for the ITER.
The globus-m diagnostics design Bulanin, V. V.; Chugunov, I. N.; Vildzunas, M. I. ...
Plasma devices and operations,
12/1/2001, Volume:
9, Issue:
1-2
Journal Article
Peer reviewed
Diagnostics which is currently installed or under active development for a newly commissioned spherical tokamak (ST) Globus-M is described. Among the commonly implemented plasma diagnostics the ...priority is given to those of the enhanced locality and repetition rate response. Technical summaries of each diagnostics are given with special emphasis on innovative approaches.