# Beam-Plasma Stabilizer for the New Type of Nuclear Power Energy Systems
## 2 Materials and Methods  
The experimental set-up was thoroughly described in paper [10], so let us consider only its main elements, presented in Figure 1. Block I included a vacuum chamber (1), cathode (2), and anode (3) units. Special sapphire windows (4) were used for observation and optical measurement purposes. The vacuum system (block II) included a turbomolecularpump that allowed one to achieve the maximum vacuum level of 5 \(\times\) 10\({}^{-8}\) Torr. High stability of the discharge conditions were achieved via the implementation of a long degassing cycle at the temperature of 700 K. The optical unit III consisted of the monochromator (7), the diaphragm (8), condenser lens (9), and a data processing system (10).  
The device flowchart is shown in Figure 2. A thermionic cathode (1) that was impregnated with barium had a diameter of 10 mm, the molybdenum main anode (2) was fabricated in the form of a diaphragm with a diameter of 30 mm and a 2 mm central hole. The main anode (MA), located within 8 mm from the cathode, was parallel and coaxial to it. The control molybdenum electrode (CE) (3) with a diameter of 30 mm was removed from the zone of the main discharge behind the MA and was located at a distance of 1 mm from it.  
The main discharge gap geometry-shaping unit was adjacent to the cathode and had the form of a metal conical shield (9). The interelectrode gap was filled with spectrally pure helium. The potential of the conical shield coincided with the potential of the cathode.  
The process of plasma diagnostics was carried out according to the method of the flat one-sided probe that was developed in [13]. The method is based on measuring the probe current second derivative with respect to the probe potential values and the subsequent calculation of the complete EVDF, which is represented as a series in Legendre  
Figure 1: Principal layout of the experimental set-up: vacuum chamber unit (I),vacuum system (II), optical system (III), vacuum chamber (1), cathode unit (2), anode unit (3), sapphire window (4), turbomolecular pump (5), mass-spectrometry analysis system (6), monochromator (7), diaphragm (8), condenser lens (9), and experimental data processing system (10).  
Figure 2: Flowchart of the device with discharge channel narrowing: cathode (1), main anode (2), external control electrode (3), heater (4), heat shield (5), cathode micro thermocouple (6), probe (7), protection alundum insulators (8), and lateral conductive shield (9).  
polynomials. During the probe measurements, all of the [PERSON]'s theory requirements were meticulously met. For this purpose, probes with a thickness of 30 \(\upmu\)m and a diameter of 0.5 mm were acquired.  
To obtain the values of the probe current second derivative, we used the demodulation method that was implemented in a PC-based measuring complex. A 100% modulated voltage \(\Delta\)U = U\({}_{0}\)(1 + cos\(\omega_{1}\)t)cos\(\omega_{2}\)t was used as a differentiating signal to increase the sensitivity of the method.  
To ensure that the device entered its operating mode, one had to perform several steps. Firstly, a discharge had to be ignited at the main anode. Then a discharge had to be ignited on the control electrode, after which a fixed value of the current had to be set at the control electrode, and the corresponding volt-ampere curve had to be recorded. In this case, in the cathode-anode gap, a diffuse luminescence characteristic of the LVBD can be observed.