# Beam-Plasma Stabilizer for the New Type of Nuclear Power Energy Systems
## 3 Results  
It is well known [10] that the EVDF structure is formed by two separate groups of electrons--thermal and beam electrons. The velocity distribution of thermal electrons is close to the isotropic Maxwellian one, while the corresponding characteristic for the beam electrons is characterized by a significant distribution anisotropy. Comparison of the thermal and beam electron's energies revealed a strong nonequilibrium of the EVDF--the mean energy values for the thermal and beam electrons were about 2 eV and 25 eV, respectively. The formation of such a EVDF structure is associated with the potential distribution over the interelectrode gap (Figure 3). The curves 1-3 in Figure 3 were recorded at different helium pressures and currents on MA and CE.  
It can be seen that for zero current values at CE (curve 3) the potential distribution is typical for LVBD, and a potential drop was formed at the anode which is an almost insurmountable barrier for thermal plasma electrons, which, in this mode, do not participate in the processes of ionization and current transport. The electrons that were emitted by the cathode were accelerated in the near-cathode sheath and form a beam with a narrow energy distribution that penetrates the interelectrode gap. The creation of thermal electrons occurs as a result of the ionization of helium atoms by the beam electrons.  
When the current at CE is nonzero, the potential distribution changes drastically--a potential jump is formed near the anode hole (Figure 3, curves 1, 2). Such an effect leads to the acceleration of thermal electrons to the energies that allow them to pass into the gap between MA and CE. In this case, the magnitude of the jump grows with increasing current at CE, which leads to a rise in the anisotropy of the thermal electrons' velocity distribution function.  
Figure 3: Potential distribution over the gap of the experimental device at different helium pressure values P\({}_{\text{He}}\), Torr: 1–3; 2–6; 3–2; currents to the MA, A: 1–0.6; 2–0.4; 3–0.2; currents at the CE, A: 1–0.04; 2–0.02; 3–0.  
Based on the data of probe measurements, the complete EVDF was reconstructed and its angular structure was analyzed. Figure 4 comprises of the diagrams that illustrate the angular structure of thermal plasma electrons' distribution function near the anode hole as a function of helium pressure and the current at the CE. It can be seen from Figure 4a, that a pressure increase leads to the isotropization of EVDF under the influence of elastic electron-atom collisions. Figure 4b shows an increase in the degree of thermal electrons' anisotropy due to the aforementioned acceleration effect at the potential jump near the anode hole, the value of which grows with increasing current at CE (see Figure 3).  
Thus, thermal electrons begin to participate in the processes of current transport. In the gap between the MA and the CE, the current transfer is carried out mainly by thermal electrons from the plasma in the cathode-anode gap, and the hole in the anode is essentially a plasma cathode.  
The current-voltage curves (registered in these modes) of the cathode--main anode (1-3) and the cathode--control electrode (4-7) gaps are presented in Figure 5. One can easily see that the curves 4-7 demonstrate significantly higher discharge voltage values compared to the curves 1-3 and thus follow the requirements of voltage stabilization in the high-voltage range.