In works [6,7], on the grounds of thermodynamic description of non-equilibrium systems with the use of phase space formalism and the multi-dimensional fundamental equation at the availability of diffusion, the processes of chemical instability generating fluctuations in a macroscopic system including the vacuum cavity of a cryogenic reservoir with the superinsulation inside it have been explained. In addition, the macroscopic system consists of a large number of particles N ^ ■*> and occupies the macroscopic volume V^ ■*> at finite density N /V. Moreover, an external influence is directed to the system — in the form of low-magnitude fluctuations of the diffusive flow with the donor gas and water vapour concentration changing in composition. In work [6], small and intermediate magnitudes of fluctuations have been considered, which most effectively deflect the system from the unstable state.

This review covers the consideration and analysis of the data being accumulated by the present time on passing of electro-sorption processes in screen-vacuum heat insulation (superinsulation) layers of big cryogenic reservoirs.

Periodic variations of the concentration of the effusion flow in the link with electro-sorption processes lead to the appearance of chemical pseudowaves. In a diffusion system with chemical reactions, information is transmitted at an infinitely high speed, as such a system related to the parabolic type. Therefore no delay periods are observed between the rate of change of the concentration parameters of effusion values and the variation of thermodynamic parameters in the thermodynamic open macrosystem being investigated. The influence of chemical pseudowaves on the
cryogen product volatility as well as on reduction of the safety degree of thermally controlled objects have been analysed.

At the investigation of a non-adequate process, the variations of volatility in identical cryogenic reservoirs during purposeful reduction of the hydrogen concentration in a clearly expressed hydrogen residual atmosphere the following effects have been detected [6,7]:

1. Effect of effusion induced hydrogen instability of the superinsulation (EIHIS)

[6,7],

2. Effect of effusion induced heat conduction instability of the superinsulation in cryogenic and vacuum facilities (EIHCIS) [6, 7],

3. Effect of multiplication of the amount of desorbed hydrogen molecules in respect to the magnitude of inflowing humid air molecules in the superinsulation of cryo-vacuum objects (MADHM) [6, 7].

The effects in heat insulation can be controlled. In order to create new heat insulation samples with a high exergy efficiency and a high safety degree, new heat-insulating structures and designs should be developed [8, 9].

As a rule, in the process of operation of big cryovacuum objects, when the heat insulation routine maintenance intervals are exceeded, a process of daily fluctuations of the residual pressure and volatility of the cryogenic liquid arises. The cryogenic reservoirs in question of the RS-1400/1.0 type (hydrogen, nitrogen, oxygen) [10] had an insignificant atmospheric effusion leak being within the tolerance by magnitude. Variations of the residual pressure and volatility of the cryogenic liquid occur in such heat-insulating cavities (HIC) with expressed symbate nature in respect to the variations of the atmospheric leak effusion component.

However for the residual pressure variations, the multiplication mode of desorption processes is characteristic as compared with the calculated effusion flow. The influence on the residual HIC atmosphere by a selective chemical hydrogen absorber based on palladinised manganese dioxide [30,31,34] has allowed to reduce the cryogenic liquid volatility from 1100 kg/day to 390 kg/day [6]. The oscillatory process of the volatility has stopped. The oscillatory process of the residual pressure occurred with the monotonously decreasing correlation coefficient (the variation of the residual medium pressure — the relative humidity) as the hydrogen was pumped out from its maximal value of 0.95 to negative values. After pumping out of the calculated amount of residual hydrogen, the correlation coefficient has changed its sign and has been monotonously increased by modulus up to the value of

0. 95. The process of reduction of the correlation coefficient has been symbate in respect to the process of hydrogen removal from HIC. The change of sign of the correlation coefficient occurred at the moment when the whole calculated amount of hydrogen had been removed from HIC [6]. Such behaviour of the correlation coefficient has caused an idea of the electronically stimulated adsorption-desorption process of acceptor or donor gas depending upon the Fermi level of the metallised screen surface. Two hypotheses have been considered:

1. Adsorption-desorption process thermostimulated in micropores.

2. Electronically stimulated adsorption-desorption process of acceptor or donor gas (depending upon the Fermi level) by the inflow of ionised oxygen and water vapour.