A direct current arc was maintained between a water-cooled iron cathode and a sodium anode in a hydrogen atmosphere up to pressures of 3 or 4 cms. With potential differences from 20 to 30 volts, a many-lined spectrum was obtained in which several bands and branches have been identified in the region between X3900 and X5100. Computations involving the usual quantum assumptions have led to the determination of the following molecular magnitudes:-X4333 band Initial state Final state J , =3.59XlO-40 gmcm 2 /"^.lOXlO-^gmcm 2 r 0 ' = 1.51 X10~8 cms r 0 " = 1.80X10-8 cms X4655 band Initial state Final state 7 / = 3.20X10-40 gmcm 2 J"=4.06Xl0~4°gmcm 2 ro' = 1.42 X 10~8 cms r 0 " = 1.60X10" 8 cms Some deviations from current quantum formulas are pointed out.HP HE object of the present work was to obtain an emission spectrum that could be ascribed definitely to a diatomic molecule consisting of one atom of sodium and one of hydrogen. Previous work with such hydrides indicated that the spectra to be expected would be of the complicated, many-lined type. 1 In the course of the present investigation many new points of technique had to be developed. The usual difficulties in handling metallic sodium were far exceeded by those which had to be overcome in securing the critical combination of conditions essential to the production of the desired spectrum. If this precise state were not maintained, quite a different spectrum was produced, either alone or so as to be dominant and altogether troublesome. Extensive work with widely different methods of excitation, showed the necessity of employing a relatively high gas pressure and a low-energy electric discharge so as to encourage molecular combinations and avoid all dissociative effects.The essential parts of the apparatus that proved most satisfactory are shown in Fig. 1. The arc chamber was made from a heavy three-liter Pyrex flask in which the arc itself was maintained between a water cooled iron cathode 11 mm in diameter, and an anode consisting of several grams of metallic sodium in a porcelain cup 1.5 cms in diameter. The 1 W. W. Watson has reported a many-lined spectrum due to a lithium hydride combination. See Abstract in Phys. Rev. 25, 887 (1925). 85

Ab8tmct-Projections of the growth of earth-sehg systems for the htter half of the 1980's show I data tmnanision requirement of 300 Mbit/s md &ow. Mission umstdnta md objectives led to the condusion that the most efficient technique to ntum the data h m 8 ensingsatellitetoagroundstrtionisthroughageosynrbronousdrtareky satellite. Of the two finlcs that are involved ( -sateIlite to relay satellite and relay satellite to grourrd), a laser system is most attractive for the sprce-tosprce link. A five-ym program was conducted which has &own the bmic technial feia'bitity of wmptishing thig link with a C02 laser system operaat a wavelength near 10 pm. The system wes a rnercury-cadmbm-telluride infraed mixer cooled to approxk m8tely 100 K by 8 ndi8tive cooler. The h r loal osciil8tor md couphgmoduhted I.ser tnnanittez use conductive& coded beryllium oxide construction. The optical 811-8 wed for t & r e -ceptionhasa~ofwminrlly92dBwitha3~bermwidthof80rru. T r r c~j i t t e r b l e s s t h . a t e n r r m d~P c q p h i t i o n o c c u r s m l~t h n n Manuscript received April 22, 1976; revised July 6, 1976. The submission of this paper was encouraged after review of an advanced proposal. are with the Space and Communication Group, Hughes Aircraft Company, El Segundo, CA 90245. Hammer, Inc., Melville, NY 11746. B. J . Peyton and T. Flattau are with AIL, a division of Cutler-PROCEEDINGS OF THE IEEE, FEBRUARY 1977 e LANDSAT-1 e TIROS-N e ITOS 0.001 O.O1 1960 i 1970 1980 Fa. 1. Space data transmission requirements. tions satellite. All intersatellite links are assumed to use laser communication systems, while all satellite-ground links use RF systems. The advantages provided by laser systems are compactness, freedom from frequency allbcation limits (which, for example, limit a &-bandlink to about 300 Mbit/s), and freedom from interference due to terrestrial RFI.Although the discussion has concentrated on a particular requirement which leads to the desirability of intersatellite links, such links have obvious utility in other applications. In domestic satellite systems, an intersatellite link would permit two satellites to serve essentially as a single system. By eliminating the transfer of data between satellites through a ground station, frequency allocations for ground-satellite links are conserved [ 181 . Similar considerations apply to international communication satellite systems [ 191 , where interregional telephony without intersatellite connections can require as many a s ' three hops-with an attendant excessive one-way propagation time.

This paper presents the results of an experimental evaluation of a new type of piezoelectric ceramic device designed for use as a laser mirror tuner. Thin plates made from various materials were assembled into a circular bimorph configuration and tested for linearity of movement, maximum travel, and resonant frequency for varying conditions of clamping torque and mirror loading values. Most of the devices tested could accept mirror diameters up to approximately 1.3 cm and maintain a resonant frequency above 2 KHz. Typical mirror translation without measurable tilt was +/-20 microm or greater for applied voltages of less than +/-300 V.

No abstract