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Based on OMFIT framework and HL-2M parameters, this paper comprehensively considers the changes in plasma density, temperature, and other transport quantities caused by the interaction of neutral beam injection(NBI) and electron cyclotron wave(ECW) with plasma. The changes in the Shafranov shift of the plasma magnetic surface center are also evaluated. Theoretically, the influence of NBI on the deposition location and current drive efficiency of the ECW is studied. According to the findings, NBI affected the position location and efficiency of the electron cyclotron current drive (ECCD) deposited on both high field side (HFS) and low field side (LFS). NBI can relocate the ECW power deposition location to the core and increase the current drive efficiency when the ECW power is deposited on the LFS. When the NBI power increases to 7 MW, the ECCD deposition location can shift to the core by roughly 0.15 normalized small radii, and the current drive efficiency can be improved by 1.3 times. Moreover, as NBI power increases, the radial region where the dimensionless current drive efficiency equals to zero gets closer to the plasma edge. When ECW power is deposited on the HFS paraxial, increasing NBI power causes the ECW deposition location to move toward the plasma edge, thus lowering current drive efficiency. This trend is caused by an increase in NBI power, which can increase the Shafranov shift of the plasma center, increase the electron density, and change the electron temperature. These studies hold great significance for achieving more effective current drive and controlling the plasma current profile and neoclassical tearing mode instability.

The blind signal separation (BSS) algorithm obtains each original/source signal from the observed signal collected by the receiving antenna or sensor. Objective/loss/cost function and optimization method are two key parts of BSS algorithm. Modifying the objective function and optimization from the perspective of neural network (NN) is a novel concept in BSS domain. $$L_2$$ L 2 regularization is adopted as a term of maximum likelihood estimation (MLE)-based objective function like in Liu et al. (Sensors 21(3):973, 2021); however, we modified the probability density function (PDF) term of the objective function and used the kernel density estimation method for time–frequency overlapped digital communication signal. Multiple optimizers are studied in this paper, and we figure out the right optimizer for our application scenario. A varies of comparison experiments—whose separation results will be provided in forms of correlation coefficient and performance index—are carried out, which indicate our method can converge quickly and achieve satisfactory separation results with performance index (PI) lower than 0.02 when signal-to-noise ratio (SNR) no less than 10dB. Additionally, it demonstrates performance of our method is better than that of typical separation—FastICA, especially for the lower SNR environment, and it shows that our method is not sensitive to the frequency overlap level (FOL) of the source signal, even FOL as high as $$100\%$$ 100 % ; it still can get high-precision separation results with $$\textrm{PI}<0.02$$ PI < 0.02 .

Impurity seeding is the major technology for divertor power exhaust. In this work, the impact of N and Ne impurity seeding on the behavior of neutrals in the divertor region was systematically studied based on the HL-2A tokamak. The results demonstrated a strong correlation between the target deuterium molecular density and the target electron temperature after N/Ne impurity seeding. In addition, it was found that deuterium atoms played a more important role in reducing the electron temperature of the target after the Ne impurity injection at Te <15 eV than that of N seeding. Moreover, the deuterium radiation atom excitation channel was stronger after the Ne impurity injection than the N impurity. It was also found that the N impurity radiation in the divertor can reach several times of the Ne impurity radiation under the high upstream density conditions. The core effective charge number Zeff was larger after the Ne impurity injection than N impurity injection, indicating that the Ne impurity was more likely to dilute the plasma.

On the basis of the OMFIT integrated simulation platform and the parameters of the HL-2M device, a hybrid scenario with a typical safety factor q profile is simulated using the joint injection method of neutral beam and electron cyclotron wave with a normalized toroidal beta (βN) of 2.39. At the same time, by analyzing the effect of impurity concentration (Zeff) and pedestal density (ne,ped) on confinement, a higher parameters hybrid scenario is obtained, with βN reaching 3.118. The research results indicate that the turbulent stabilization effect caused by Zeff gradually decreases from strong to weak with the increase of Zeff, whereas the radiation power loss increases linearly as Zeff increases. Consequently, there exists an optimal Zeff value for optimal confinement. In addition, it is found that the optimal Zeff value decreases with the increase of ne,ped. The research results are crucial for the HL-2M device to accomplish the 1 MA advanced scenario discharge target, and they serve as a reference for future impurity seeding experiments.