A brief review of established methods shows that only with the Berthelot technique is it possible to see a finite volume of liquid in sustained mechanical tension. A short discussion of the practice and theory reveals two uncertainties with the conventional technique : that of the determination of a true filling temperature, and the influence of compliance by the glass on the tension developed. A description is then given of a modified apparatus with which these difficulties do not arise. The tube is formed into a coil which deflects sufficiently to indicate internal pressure or tension, and by monitoring these deflections with a distance meter a record of pressure/ tension against temperature can be made. The course of a typical run is shown from which the excess pressure, filling temperature and limiting tension may all be estimated with much greater precision than befoie. The orders of magnitude of the results obtained are indicated, and a possible influence of non-uniform gaseous supersaturation is suggested.

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In this paper a possibility of precise correction of phase distortions due to inhomogeneities of turbulent atmosphere at a near ground surface path 2 km long is experimentally proved. Highly efficient transmission of laser radiation pulses of 20 nsec duration with energy up to 20 J through the path with nearly diffraction limited quality is achieved.Effectiveness of laser radiation transmission at large distances for near surface paths is mainly determined by wave front distortions due to atmospheric turbulence.Compensation of wave front distortion by phase conjugation (PC) method is thoroughly studied theoretically and experimentally in several papers [ 1 -8 ]. It has been shown that the wave front conjugation phenomena may permit to compensate the distortions due to atmospheric turbulence during laser beam transmission. But the compensation of atmospheric turbulence by means of PC devices up to present time is studied insufficiently.The purpose of the present paper is an experimental study of the possibility of compensation of distortions due to atmospheric turbulence and implementation of delivery of sufficient laser energy values through a near ground surface path.The experimental setup diagram is shown in Fig. 1 . The laser radiation pulse formed in the master oscillator 1, is directed through a 2 km long run to the receiving-transmitting telescope, formed by mirrors 2 and 3, ftirther to a two-pass amplifier 4 with a stimulated Mandelstam-Brillouin scattering (SB S) mirror. The amplified radiation hit upon a SBS mirror 5 where due to SBS process a Stokes radiation wave with a phase-conjugated wave front directed precisely in the opposite direction was formed. After passing through the amplifier the conjugated wave was amplified in the amplifier and passed through the range SPIE Vol. 3733 • 0277-786X/99/$1O.OO 249 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/27/2015 Terms of Use: http://spiedl.org/terms

YBa,Cu,O,-, multicrystalline ceramics were shaped into one-turn coils. The RF performance of the coils was evaluated by measuring the Q-value at 77 K from 1.3 to 270MHz and comparing it with that of a Cu coil of the same geometry. The coils were also tested as NMR detection coils. In a poorly magnetically shielded environment the multicrystalline YBa,Cu,O,-, performed less well than Cu in the frequency range studied. Q was significantly lowered by applying a magnetic field. The temperature dependence of the Q-value also was measured at 100 MHz, from 77 K to well above the superconducting phase transition temperature.

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