In studies [30, 31], the identical method was used to determine the energy deposi­tion to the gas. After irradiation of the laser cell with a short neutron pulse, damping pressure oscillations arose in the gas. From a comparison of the amplitude of the first peak of dependence of the pressure on the time with analogous amplitudes of dependencies obtained by means of computer simulation of gas dynamics (here the values of the energy transported to the gas are varied), the share of the energy of fission fragments transmitted to the gas was determined. In both studies, this percentage was roughly half the value obtained from direct calculation of the fragment energy deposition by the described methods. It is noted in [30], however, that direct measurements of the number of fission fragments emitted to the gas agree with the calculated values.

The conditions of conduct of experiments in these studies had some differences. For instance, in [30] a rectangular cell with plane-parallel arrangement of the layers containing uranium was used; the half-width of the neutron pulse was t1/2~0.15 ms; only argon was studied, with three values of initial pressure (0.7; 2.8; 4.14 atm). In [31], a cylindrical cell was used, with a uranium layer deposited on its internal surface (on a section with length 0.65 that of the total length). The half-width of the neutron pulse was t1/2 ~ 0.4 ms. Experiments were conducted with helium and neon with several values of pressure, in a range from 0.5 to 5 atm.

In study [31], the energy deposition was also evaluated from the pressure established after damping of the fluctuations. From the oscillograph curve shown in [31], it follows that the time of pressure establishment is ~10 ms. In the opinion of the authors [31], corrections allowing for the cooling of the gas through heat conduction were not great.

It should be noted that the calculations of [19, 20] (see also Chap. 8) of thermal and gas-dynamic processes in laser cells with the same internal diameter as in [31] (2.8 cm) showed that a relative reduction of pressure of ~20-35 % occurred in the gas due to heat removal from the walls of the cell after ~10 ms (from the start of the irradiating pulse with half-height duration of t1/2 ~ 3 ms). We also make mention of analogous calculations [34] for a rectangular cell with dimensions of 1 x 7 x 60 cm, from which it follows that in ~4 ms, around 10 % of the deposited energy departs owing to thermal conduction through the cell walls.

As one possible reason for the discrepancy of data between theory and experi­ment, it is proposed that a significant portion of the deposited energy does not have time to be thermalized, and is carried to the cell walls in the form of luminescent radiation [30], in particular through transformation into UV radiation of excimer molecules [31]. Another reason for the reduction in the energy deposition might be the low quality of fabrication of the active layers. Unfortunately, study [31] pro­vides no data on the specific energy deposition to the gas, which hampers analysis of the results of this study.