When a transverse-discharge CO2 laser with forced flow is pulsed rapidly, the minimum time between arc-free pulses is substantially greater than the time predicted by the ratio of electrode width to gas velocity. The maximum pulse rate is predicted accurately by flow-model solutions that determine the time required to remove the glow-discharge products from the interelectrode space. The predictions were experimentally verified to a maximum pulse rate of 1 kHz using planar electrodes in a closed-cycle wind tunnel.

A method for graphically presenting fully developed nucleate boiling heat transfer correlations currently being used for design purposes enables the engineer to compute a numerical value of the boiling heat flux, or corresponding wall superheat, rapidly and without knowledge of the physical properties of the fluid, other than at one arbitrary reference state. ACONVENIENT method is illustrated for presenting boiling heat transfer correlations in engineering handbooks or design manuals. This method is applicable to such correlations as those given by Engelberg-Forster and Grief (7), Rohsenow (3), and Seader, Miller, and Kalvinskas ( 4 ) . If the ratio of the functions f(q/A,AT,) and f(q/A,ATJref, which are determined from the chosen boiling correlation, are plotted against reduced pressure, it forms a single curve for a number of different fluids. The method is, thus, analogous to the law of corresponding states and is demonstrated here with the Engleberg-Forster and Grief correlation, for which j ( q / A,AT,) becomes A T s / a . A curve of ( A T , / d G ) / ( A T , /

The author is to be commended for his study which extends the earlier incompressible flow analysis proposed by Cotter (author's reference no. [1]). When the design operating temperature is above ambient conditions, a heat pipe will encounter a sonic vapor How limit during heating up due to very low vapor pressure and vapor density. There is, however, a peculiarity with sodium vapor flow which bears elaboration. Any comments that Dr. Levy may have on this woidd be most appreciated.

This is an informal report intended primarily for internal or limited external distribution. The opinions and conclusions -l G! .

No abstract