## 4 Conclusions  
Here, we investigated the energy and spatial characteristics of high-energy yellow 589 nm KGW Raman lasers operating in single-pulse mode, as well as their dependence on pump intensity and the laser cavity configuration. The study shows the following:  
1. The largest energy efficiency of KGW Raman lasers can be obtained with the use of a flat cavity. A slightly lower energy efficiency is observed with unstable cavities. Worse energy characteristics are obtained when using stable spherical cavities. The energy efficiency reduces with a reduction in the resonator mirror's radius of curvature. This is explained by the worse lateral overlap between the pump radiation and Stokes radiation, because the spatial distribution of the Stokes radiation depends on the cavity configuration. 2. The best angular characteristics (lowest angular divergence) are obtained using unstable resonators. Lasers with flat cavities have a 2-3 times larger angular divergence, and worse characteristics are obtained with stable spherical cavities. We can conclude that stable spherical cavities in high-energy Raman lasers have no advantages, and there is no practical interest in their application. 3. A reduction in the mirror's curvature in unstable-cavity lasers leads to a better angular divergence. At the same time, the energy efficiency is reduced. Thus, for a given laser application, optimization of the mirror's curvature is required. 4. An increase in pump intensity leads to an increase in the angular energy divergence in lasers with all types of resonators. However, in lasers with flat cavities, the angular size of the core remains almost unchanged, and the angular energy divergence increases mainly due to wing growth. In lasers with unstable cavities, this process requires additional study. Note that the angular characteristics of high-energy Raman lasers are much worse than those of conventional solid-state lasers. A 5.2 mrad angular core width, obtained in an unstable-cavity laser with a convex mirror of 750 mm, pumped at 350 MW/cm\({}^{2}\), is 26 times larger, than the diffraction-limited value. The angular energy divergence of Raman lasers with a flat cavity is 2.5-3 times larger than that of Ti:Sapphire lasers under the same conditions. The main reason for this, in our opinion, is the very high gain level, which is typical of such Raman lasers but not achieved in most conventional lasers. A similar worsening of the angular characteristics in conventional lasers is observed in multistage pulsed oscillator-amplifier laser systems without interstage spatial filtering, where amplified spontaneous emission leads to inferior spatial and temporal contrasts. Roughly speaking, we can consider the 589 nm radiation from KGW Raman lasers as a combination of two main components: radiation in the core and radiation in the wings. In our opinion, radiation in the wings does not represent the tails of resonator modes, especially at high pump intensities, but has another origin. Under some of the above-mentioned conditions, we observed signs of parametric generation, which contributes to part of the energy in the wings. Another contribution may be from the scattering of the core radiation with a subsequent strong amplification in the scattered radiation. Note that, besides 589 nm radiation, we also observed weak radiation at 621 nm, generated in the form of straight and conical beams at pump intensities much lower than the threshold of third-order Stokes Raman generation. This radiation can be generated via secondary parametric processes, described theoretically in [16,17]. This radiation was very weak, with an energy of less than 0.1 mJ. Thus, such processes in practice are not important. We intentionally did not use the M\({}^{2}\) parameter to characterize the high-energy Raman laser beam quality. The determination of M\({}^{2}\) is based on intensity profiles, and so it does not take into account the low-intensity radiation propagating in the wings at large angles to the beam axis.