RESUMO
A new neutral particle analyzer (NPA) diagnostic based on single crystal chemical vapor deposition (sCVD) diamond detector that provides measurements of fast ions has been designed and installed on HL-2A tokamak. Diamond detectors have been applied in some magnetic confinement fusion devices due to their outstanding properties of compact size and radiation hardness. This DNPA can measure energies above 13.4 keV. The line of sight (LOS) of the DNPA intersects with the NBI No. 2 with a tangency radius of 154.8 cm. Due to the pitch angle defined by the LOS and geometry of the diagnostic, the DNPA is mainly sensitive to trapped ions. To interpret the energy spectrum and verify the feasibility of the design of the DNPA, a Monte Carlo code called FIDASIM, which is a synthetic diagnostic code that simulates fast ion D-alpha and NPA signals, is applied to model the neutral flux reaching the detector. The results show that the flux is mainly contributed by the low energy fast ions (E < 10 keV) and it is mainly coming from the active components, the passive signal is dominant in the high energy region (E > 15 keV). The modeling features the ability to distinguish between active and passive signals, and the simulated strong passive signals are suggested to come from charge exchange between cold neutrals and fast ions around the plasma edge. In addition, despite the large ratio of halo neutrals, essentially it has a limited contribution to the energy spectrum.
RESUMO
The wide-angle view imaging system, in terms of a tangential view diagnostic with field of view (FOV) of 56.8° and a downward-looking diagnostic from the top of the machine with FOV of 94.7°, has been newly constructed for the first plasma of the HL-2M tokamak achieved in December 2020. Its mission in this stage is to monitor the plasma evolution during its startup, sustainment, and disruption in the visible spectral range as well as the plasma-wall interaction. For the latter ultrawide view diagnostic, nearly three-quarters of the divertor region and half the area of the inner wall are in the view range. Both the diagnostics are characterized by a similar optical structure, i.e., the light emission from the plasma is collected by a front-end lens and transferred through an imaging fiber bundle to the camera. This optical structure is suitable for application in the complex tokamak environment mainly because the fiber bundle is flexible. Photos of glow discharges are acquired prior to the first plasma for testing the FOVs in the vacuum vessel. The spatial resolution is â¼4mm for the tangential view diagnostic and â¼10mm for the downward-looking diagnostic. The temporal resolutions, ranging from 90 to 360 Hz by changing the region of interest or binning acquisition mode of the color camera, are applied to record the plasma evolutions and/or dust creation events during the first plasma campaign.
RESUMO
On HL-2A tokamak, supersonic molecular beam injection (SMBI) has been developed as a routine refueling method. The key components of the system are an electromagnetic valve and a conic nozzle. The valve and conic nozzle are assembled to compose the simplified Laval nozzle for generating the pulsed beam. The appurtenance of the system includes the cooling system serving the cooled SMBI generation and the in situ calibration component for quantitative injection. Compared with the conventional gas puffing, the SMBI features prompt response and larger fueling flux. These merits devote the SMBI a good fueling method, an excellent plasma density feedback control tool, and an edge localized mode mitigation resource.
