The RF-driven negative ion source has a steady state characteristic and will be a promising ion source for neutral beam injection (NBI) in the future. Cesium (Cs) injection is an efficient method to enhance the yield of negative ions during plasma discharge. In order to support the engineering and physical research in this field, the Cs oven prototype has been developed for negative ion source based neutral beam injector at ASIPP. This article presents the design details of a Cs oven system, including the constant temperature control system, the mechanical structure of Cs oven, and the surface ionization detector (SID). SID is a measurement method for the cesium flux in the nozzle. The experiment results of constant temperature control system show that the control accuracy and function meet the requirements of device operation. Meanwhile, the simulation analysis of Cs vapor concentration has been carried out in this paper. According to the simulation results, the graph of total Cs flux is given in the article, which presents the reference for the subsequent device testing.

Neutral beam injection is recognized as one of the most effective methods for plasma heating. According to the requirements for physics experiments of the Experimental Advanced Superconducting Tokamak (EAST), two beamlines for neutral beam injection were built in 2014. In order to meet the diverse requirements of magnetic confinement experiments, recent attempts have been carried out for arc power control of a neutral beam injection ion source. A test system was added to the arc power control system. It provides a new method to smoothly change arc power during a discharge. According to the experimental results of controlling arc power, the fesibility of varying the arc power was verified in the duration of discharge. Meanwhile, the test system achieves the remote setting of arc power parameters.

Neutral Beam Injection (NBI) is one of the four efficient ways of assistant heating on the Experimental Advanced Superconducting Tokamak (EAST) device. Measures have been taken to ensure more reliable monitoring of NBI components’ thermal data. Infrared thermometers, unlike surface-mounted thermocouples, have the advantage of non-contact and thus will not cause interference and get far less chance of malfunctioning [Childs et al., Rev Sci. Instruments 71, 2959–2978 (2000)]. In this paper, the remote infrared temperature measurement with optical fiber is reported to meet the requirement of the EAST-NBI diagnostic system. Some tests have been conducted on the remote infrared temperature measurement under the working condition, and an atmospheric propagation simulation was performed to estimate the atmosphere absorption. The results indicate that the detector’s response is in line with the theory, and the atmosphere absorption within a certain wavelength should not be ignored. Temperature measurement error is within one percent at temperatures above 200 °C. So, for the temperature range of 200–600 °C, the remote infrared temperature measurement by the optical fiber can fully meet its expectation.

Radio frequency negative ion source is the best choice for neutral beam injection (NBI) in future nuclear fusion. Cs injection is an important means to increase the yield of negative hydrogen ions. In addition, the stability of the ion source is influenced by the distribution of Cs inside the source in the vacuum phase and plasma phase. Liquid Cs is heated into Cs vapor and then diffused into the source through a nozzle, the shape of which has a direct effect on the angular distribution of the Cs flux. This article studies the ballistic transport process of simulating three types of nozzles: cylindrical, bent, and edge-cut by developing a Monte Carlo program. The results show that the angular distribution of Cs flux from cylindrical nozzles approximates the cosine square distribution in the case of the same nozzle diameter. In comparison, the peak coverage density increases with a certain shift of the distribution state relative to the cosine square for bent and edge-cut nozzles. By analyzing the flux distribution of different nozzles, this study provides a reference for subsequent simulations of Cs and the design of Cs injection systems.

The fundamental requirements for experimental advanced superconducting tokamak neutral beam injection (EAST-NBI) are high power and long pulse. The electrostatic probe’s inherent properties, which affect the probability of electrode ignition, cause the extraction beam current to decrease with increasing extraction time in the probe feedback mode of arc power. A power feedback technique of arc power supply is suggested to stabilize the beam current and lengthen the extraction time. The output power of the arc power supply is adjusted via feedback to keep the plasma density in the arc chamber largely steady by multiplying the output voltage and current. The beam current decrease in the arc power feedback mode is substantially smaller than that of the probe feedback, which is helpful for extending the extraction time.