Search

This report describes the theoretical development of Statistical Energy Analysis (SEA). The historical development of the subject and an extensive annotated bibliography are included to add perspective to the technical discussions. Those aspects of random vibration theory are reviewed first. Then, the coupled vibration of randomly excited resonators is discussed. Using these results as a basis, the SEA model of coupled systems is introduced, and the consequences of the model are derived. From these basic relationships, a scheme for the prediction of vibration levels in coupled, randomly excited, resonantly vibrating systems is developed., See also Part 2, ADA006414.

Dielectric resonators have applications as low-loss compact filters in the microwave region. Tuning characteristics of dielectric resonators that might allow for temperature compensation and frequency variability were investigated both theoretically and experimentally at L band. A secondary dielectric resonator that is offset in frequency from the tuned resonator provides a maximum tuning range of approximately 10 percent before an additional filter loss of 3 dB is incurred; the rate of tuning is slow since it is done by changing the resonator coupling (spacing). For fast tuning, a varactor is used in a coupled resonant circuit. Frequency changes can then be made in a time interval approaching 1/(filter bandwidth), but in this case the maximum tuning range before an additional filter loss of 3 dB is incurred is reduced to 2 percent of the filter frequency.

Contents: Nonlinear phenomena in quartz crystals; Crystal resonators for filters and oscillators; Material properties and processing techniques; Frequency stability and its measurements; Crystal oscillators; Surface acoustic wave devices; Atomic and molecular frequency standards; Standard frequency and time distribution., See also report dated 1973. AD-771 042.

An investigation was made of the behavior of a transferred-electron device (TED) in a multimode resonant microwave cavity, to design such cavity and TED to optimize the number of allowed memory states in a given overall bandwidth, and to initiate a theoretical and experimental study leading toward development of a compact multimode cavity structure suitable for ECM frequency memory applications above 8 GHz. The study includes but is not limited to microstrip resonators. TE memorizers were designed and constructed using coaxial, waveguide, and alumina microstrip circuits. Operation between 10.34 and 12.46 GHz with 17 states spaced about 132 MHz apart was demonstrated with a 2-in. x 2-in. x 0.025-in. alumina circuit. A 5-foot waveguide circuit has operated between 9.75 and 10.82 GHz with 16 states spaced about 71 MHz apart, as was a 7-foot coaxial circuit between 11.0 and 11.77 GHz with 18 states spaced about 45 MHz apart. Switching between states has been achieved with pulsed rf input signals as short as 0.1 microsec.

The changes in the resonance frequencies of circular crystal plates subject to initial bending stresses are studied. The plate is flexed as a cantilever clamped near the edge and stressed by a transverse, concentrated force applied at a point diametrically opposite the support. A system of plate equations which takes into account the nonlinear effects due to the large, initial deflection and to the third-order elastic stiffness coefficients in the stress-strain relations is employed. In obtaining the initial fields caused by bending, strain components are assumed to be small, but large gradient of plate deflection and large rotations of the plate element about x sub 1 and x sub 3 axes are permissible by retaining their quadratic terms in the strain-displacement relations. The changes of resonance frequencies of fundamental thickness-shear vibrations are calculated for rotation Y-cuts of quartz piezoelectric crystals. The calculated frequency changes are compared with experimental values as a function of the magnitude of the position, the azimuth angle psi, and also as a function of the magnitude of the force P.

A new type of unstable resonator has been developed that permits multiple-selected-line operation. Selected-line operation is obtained with a diffraction grating oriented at an angle different from the Littrow angle. Secondary feedback mirrors at the appropriate angles provide an independent three-element cavity for each wavelength selected. Two types of multiple-selected-line unstable resonators are considered: (1) an edge-coupled design, which produces an annular beam with a 45-deg output coupling mirror, and (2) a continuously coupled design, which uses the primary zero-order beam as output. Experiments have been carried out with a multiple-selected-line unstable resonator on a CW HF laser. Selected-line operation was obtained on the P2 and P1 HF transitions in a continuously coupled design.

Effort on the High Power CO Laser Program is reviewed. The program is directed toward the development of the required CO laser technology, the required component technology, and the design and construction of intermediate power laser devices. The results of analytical and experimental investigation of the basic characterisitcs of the laser and data from a high pressure electrically excited CO laser device are discussed. (Author)

A specified formula Y(0.428)Er(0.500)Tm(0.067)Ho(0.005)LiF4 was used as a first approximation to a laser system whereby the necessary broad pump bands and fast, efficient laser excitation could be obtained. Laser rods were cut from single crystal ingots grown by a reactive atmosphere process (RAP). Thermal conductivity, hardness, elastic modulus, rupture strength, radiative characteristics, and laser test data were measured to determine the laser performance characteristics of Ho:YLF. Development of RAP Ho:YLF growth procedures provided proof of practical, congruent melting behavior. Electron probe, spectrographic analysis, and backscatter measurements showed R(3+) (R = Y + Er + Tm + Ho in Ho:YLF) acted as one ionic species in crystal growth. Glass-like optical quality Ho:YLF was RAP Czochralski grown at 5 mm/hour. A short investigation of Bridgman growth indicated that higher yields and inexpensively scaled-up rod production technology can be developed.

The report treats a single-mode resonator plate with equal mass coatings on its surfaces and excited by an electric field in the thickness direction. The usual restriction to low piezoelectric coupling coefficient is not made. From simple considerations regarding the equivalent network, the exact equations for the critical frequencies of interest are shown to follow directly. These are used throughout without approximation and solved numerically. Use of the exact relations allows high coupling materials to be covered as easily as low. Families of curves showing the variations of the resonance and antiresonance frequencies over a wide range of values of mass-loading, coupling coefficient and harmonic number are given. A new plateback parameter, valid for all piezoelectric substances, is also introduced. (Author)

The described research provided fundamental theoretical support of the high-energy laser program, particularly with regard to concepts germane to that program several years hence. The work has centered in four major areas: propagation of intense radiation, laser theory, amplifier theory and molecular physics (particularly of the water molecule). This report summarizes the work completed under the contract and provides references to more detailed accounts of that work published elsewhere. Included are abstracts of papers published (or to be published) elsewhere. Among the highlights of the collected final report are a strikingly successful, yet simple, model of the H2O molecule; a very promising scheme for a soft X-ray laser; further advances in the multimode unstable resonator theory; and justification of the rate equation approach to treating lasers with cascade transitions.

The interaction between an unstable resonator and a cw diffusion-type chemical laser with turbulent or laminar mixing is analyzed by means of geometric optics and a simplified chemical model. Both cylindrical and spherical optics are considered. The radiation is assumed to be diverging, i.e., converging radiation is neglected, and the gain region is assumed adjacent to one of the resonator mirrors. Laser performance is found to depend on the magnification, the ratio of pumping to collisional deactivation rate, the normalized diffusion distance, the normalized axial location of resonator axis, the normalized axial length of resonator, the mirror absorptivity, and the net zero power gain. Analytic solutions are obtained for the limiting cases (M - 1) mach < and 1/M mach <. In the former case, the laser medium is almost completely saturated, and resonator efficiency is high. In the latter case, the radiation incident on the gain region originates near the optical axis and is uniform.

An experimental study was performed on integer and integer plus one- half valued equivalent Fresnel number positive branch confocal unstable resonators in a DF-CO2 flash-photolysis chemical laser. Near diffraction limited beam quality was obtained for a range of geometric output couplings from 30% to 77%. No dependence of beam quality on the resonator Fresnel number was found. This was true for uniform medium conditions as well as perturbed conditions where significant phase perturbation were introduced into the optical resonator. Extensive medium diagnostics were performed on the DF-CO2 laser and the results presented.

Edited trans. of Elektrotekhnicheskii Institut, Leningrad. Izvestiya (USSR) v69 n101 p69-74 1972, by Catherine M. Barber.

A nitrogen laser which combined the 'Nanolite' pulser with a resonator geometry resulted in a low threshold (3.3 kV) and a 100 kW laser output in the case of a 14 kV pulse voltage. Thus the energy conversion efficiency rose to 0.35%. The beam divergence was reduced to approximately 1 mrad by the resonator. This represents considerable progress in regard to efficient, low voltage and high repetition rate nitrogen laser operation. The study to correlate soft X-ray spots with the hard radiation in a 1 kJ plasma focus showed that field structures leading to the appearance of soft X-ray spots are always present in this plasma focus. These field structures represent m = 0 plasma instabilities and do have a direct influence upon the observed neutron emission. (Author)

The report calculates the characteristics of a gas-dynamic laser in a mixture of CO2-N2-He with a flat resonator. The system of equations describing the processes inside the resonator is analyzed and solved numerically. Inverse population of CO2 laser levels is caused by the preliminary expansion of the given mixture through a flat hyperbolic nozzle. The dependences of output power on the coefficients of mirror reflection, resonator length, pressure, and composition of the working gas mixture are obtained., Edited trans. of Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki (USSR) n5 p33-40 1972, by Paul J. Reiff.

The objective of this program is the development of wideband limiters in the frequency ranges of 12 to 14 GHz and 14 to 16 GHz. The report discusses theoretical and experimental investigations to design and build frequency selective ferrite power limiters with given technical specifications., See also report dated Apr 73, AD-759 951.

A new theory has been formulated whereby the electromagnetic field inside resonator filled with an active medium is described through an expansion of the field into an angular spectrum of plane waves. The resonator is composed of two identical, circular reflectors of arbitrary size, focal length, and axial separation and contains an isotropic, homogeneous, saturable amplifying medium. This theory properly accounts for the vector properties of the field, is not limited by the usual paraxial approximations, and provides integral expressions for the spatial distribution of the field over the interior of the resonator in three dimensions. The expression for the transverse electric component of the field was evaluated numerically for several of the lower loss modes in confocal, spherical, and unstable resonators with linear dimensions the order of 10 wavelengths. These data indicate that some of the modes in confocal and spherical resonators are unstable, if the resonator has dimensions of a few wavelengths. The effect on the spatial distribution of the resonator field due to saturation of the amplifying medium is slight if spatial hole burning is neglected. The electromagnetic field given by this theory was also quantized, and the resulting formulation resembles the quantum theory for radiation in a closed resonator. (Author)

Refined analyses and measurements showed that the thermal effects due to pumping at 27,000 joules causes the 6-inch diameter 1-inch thick Nd-doped glass disc to warp with a radius of curvature of 370,000 cm. With this warpage the out-of-plane displacement of the disc is about 3/4 wavelength at 1.06 micron. Optical coupling and pumping measurements were carried out on the 3-inch disc pump assembly. After many flashes, with 9000 joules and using ultraviolet and infrared filters, there was no measurable damage to the 1.06 micron high reflective mirror. A preliminary analysis has been carried out on the amount of distortion or deformation permissable in a plane-parallel mirror high Fresnel number Fabry-Perot resonator before the losses introduced become significant. Tipped etalons offer the possibility of mode selection at high power levels. An analysis was carried out investigating the various parameters affecting the design of such mode selectors.

Additional experimental results with model 2 of the monotron oscillator are described. Oscillations were observed on resonances ranging from the TE sub 6,1,1 at 40.7 GHz to the TE sub 10,1,1 at 76 GHz. Peak power outputs of up to 25 W (not including a 3 dB factor for thermistor efficiency and insertion loss of waveguide components) have been measured. Some difficulty was encountered with a bad connection between the aluminum collector film and its kovar support. The tube was disassembled; a stainless steel mesh was installed as a beam collector, and the tube was reassembled. Detailed measurements of the rf output pulse shape were made. A rise time in the range of 5 to 10 nsec was observed. The possibility of constructing an oscillator for 337-micron wavelength (890 GHz) is investigated. Dielectric loading of the TE sub n,1,1 cavity with a thin film of dielectric on the cylindrical wall of the cavity appears to be a good approach for the circuit of such an oscillator. (Author), Continuation of contract DA-28-043-AMC-00480(E).

The article describes the design of a ruby maser and the amplifying properties of ruby crystals of varying chromium ion doping. The dependence of the voltage gain-band width product on the concentration is evaluated on the basis of the spin-lattice relaxation processes. Reference is made to experimental values of the spin-lattice relaxation times for ruby crystals measured at T = 20.3K. The noise behavior is determined experimentally and compared to theoretical values. This maser was found to have considerable advantages in service on account of the inexpensive cooling agent and the relatively low pump capacity., Edited trans. of Hochfrequenztechnik and Elektroakustik (East Germany) v75 n5 p163-167 1966.

A gas-optical quantum generator is a source of coherent monochromatic high-intensity radiation. It is intended for use in a system which uses monochromatic light rays and is subjected to the effect of different mechanical and climatic factors as working conditions. The basic instrument is a plane-sphere type resonator, formed of two quartz mirrors with single layer dielectric films, between which the active element is located. The instrument is designed to allow the replacement of the active element after the guaranteed service life without requiring special equipment or highly qualified service personnel. When necessary, the instrument can be used with a high-frequency generator (GVCh-1 or GV-8). Included in the article is a brief list of the specifications of the instrument., Trans. of Pribory i Tekhnika Eksperimenta (USSR) v11 n3 p234-235 May-Jun 66, by George G. Weickhardt.

A nonferrous charged-particle accelerator that contains a vacuum chamber, resonator, injector, and current-conducting buses is described. It is distinguished by the fact that an equalizing central bus is used to accelerate particles of the same sign in opposite directions. The accelerator is designed in the form of a nonsymmetrical 'racetrack' to assure the intersection of particle beams. (Author), Bezzheleznyi Uskoritel Zaryazhennykh Chastits, unedited rough draft trans. of Patent (USSR) 168 808, appl. 829694/26-25, 8 Apr 63.

Contents: Circuits of Parametron Frequency Dividers; Narrowing of Emission of a Ruby Laser with a Complex Resonator., Unedited rough draft trans. of Moscow Univ. Vestnik. Seriya 3: Fizika Astronomiya (USSR), v20 n5 p89-92 1965.

The objective of this program is to investigate rf interaction circuits and stagger-tuning techniques leading to at least a 50% improvement in the 1 db bandwidth of high-power klystrons over the current state-of-the-art. In this report, the computer program used to predict the small-signal gain vs. frequency response of stagger-tuned klystrons is described. Modifications of the program to extend its use to calculations involving extended-interaction resonators and double-tuned resonators are also described. Comparisons between experimentally measured gains and bandwidths of two conventional klystrons and the theoretical predictions of this program are presented. It is seen that the prediction of gain variation with frequency is very good. (Author)

As an effort to summarize work done by various investigators in the field of acoustic filter design and theory, most of whose work was Government sponsored, this report is a description of the various types of acoustic filters and a brief explanation of the theory upon which their designs were based. Theoretical and experimental studies of the various filter designs are described and discussed. A proposed program of further study of acoustic filter design principles is presented. (Author)

A discussion is presented of an electroacoustical temperature-frequency converter., Trans. from Priborostroyeniye No. 2, pp. 11-13, 1963.

The dependence of emission power and polarization of the helium-neon laser on transverse magnetic field and with change in resonator quality is investigated. The possibility of emission with circular polarization in a laser with Brewster windows has been established., Trans. of Izvestiya Vysshikh Uchebnykh Zavedenii. Fizika (USSR) v11 n10 p130-134 1968.

This report describes an investigation of circuit techniques to minimize spurious responses in varactor-tuned filters. Design equations for the center frequency, bandwidth and insertion loss of single and multiple-resonator filters are presented. Series-resonant filters with one and two resonators were constructed and measurements of their performance characteristics were made. One- and two-resonator filters were also constructed using a pair of opposingly biased varactors (push-pull circuit) for each resonator. Measurements show that such a circuit can significantly reduce the second-harmonic generation and the response to a signal at one half the tuned frequency.

An investigation was made of a ruby laser operating in a pulsed Q- switching mode. Q-switching was controlled by rotating the prism of total internal reflection. The giant pulses obtained from the ruby laser differed from the pulses of the neodymium laser by their parameters. A neodymium laser generates a single pulse at a prism rotation speed of 25,500 rpm and a pumping energy of 2020 joules, while the ruby laser with the same rotation speed and a smaller pumping energy (1520 joules) generates 2-3 pulses which diminish in power. The parameters of ruby and neodymium lasers operating under similar conditions were compared. Neodymium glass rods and ruby rods with identical dimensions were used. The illuminator, the rotating prism, and the electrical and measuring parts of the installation in both cases were the same. The prism rotated at 24,000 rpm. The optimum mirror from the emergence side in the neodymium laser had a reflection coefficient of 60% and in the ruby laser, 42%. The investigations showed that the rate of resonator Q-switching, which determines the character of the laser emission, depends not only on the rotation speed of the prism but also on the optical properties of the active substance., Trans. of Zhurnal Prikladnoi Spektroskopii (USSR) v4 n5 p403-409 1966.

Design changes in the improved version (model 2) of the monotron oscillator are discussed. Cold test work is described which has led to what appears to be a good solution to the problem of orienting the resonances in the oscillator cavity for good coupling to the output waveguide. Construction and initial experimental results with model 2 are described. Oscillation has been observed in resonances ranging from TE sub 6, 1, 1 through TE sub 9, 1, 1., Continuation of Contract DA-28-043-AMC-00480(E). See also AD636772.

The purpose of this program is to investigate methods for improving the bandwidth capabilities of high-power klystron amplifiers. The objective is a 1 db bandwidth improvement of at least fifty percent over the current state of the art. Particular emphasis is being placed on the study of extended- interaction resonators, and the possible optimization of these resonators through the use of mode overlapping. The results of the initial investigation into the effects of mode overlapping in extended-interaction resonators is presented. This investigation has been primarily concerned with the influence of a number of different parameters on the interaction impedance, bandwidth, and frequency response of the resonators. The parameters of particular interest are the coupling between the two cavities, the degree of external loading and the location of the external load, the beam synchronization parameter, and the relative frequencies of the two cavities. The initial analysis has been restricted to two-gap resonators. It is shown theoretically that the bandwidth of extended-interaction resonators can be increased through the use of mode overlapping. Comparisons with the bandwidths of other types of resonators at a given maximum impedance level show that a two-gap extended-interaction resonator with mode overlapping can have a 1 db bandwidth advantage of approximately three to one over a two-gap, single-mode, extended-interaction resonator, and close to four to one over a conventional single-gap cavity.

The objective of this program has been to investigate rf interaction circuits and stagger-tuning techniques leading to at least a fifty percent improvement in the 1 db bandwidth of high-power klystrons over the current state-of-the-art. In this report, the findings of the final phase of this contract are presented. The major part of the effort during this final reporting period included: the completion of large-signal efficiency calculations across the band assuming a filter-loaded output resonator, the final theoretical design of the buncher section, theoretical stability calculations on the filter-loaded output resonator, and cold test measurements on a filter-loaded extended- interaction resonator. The measured interaction impedance obtained with the cold-test filter-loaded output resonator closely approximated the impedance assumed in the theoretical efficiency calculations. The final buncher section, designed with the aid of the small-signal computer program, yielded a nearly constant rf drive current to the output resonator, as was assumed in the large- signal efficiency calculations. The small-signal analysis indicated that conventional single-gap resonators are to be preferred over extended-interaction resonators in the klystron buncher section at the high power level considered in this study.

Electronic broadbanding is a technique whereby very low frequency (VLF) antennas can be resonated (retuned) synchronously with a frequency-shift- keyed (FSK) signal for transmission of binary data at rates well over 1000 baud. The thesis investigates the transmitted energy density spectrum for an electronically broadbanded VLF antenna system in which a frequency shift can occur only at the instant of an antenna-current zero-crossing with positive slope. A computer solution shows that the transmitted spectrum is approximately equivalent to the spectrum of an ideal, constant amplitude, FSK signal. A further investigation, again by computer program, shows that if the total frequency shift between the marking and spacing frequencies occurs over a finite period, rather than instantaneously, then the spectrum's sidelobes will be reduced significantly.

27Cavitation thresholds in water were measured as a function of frequency, dissolved gas, ambient pressure, and suspended particle size. The apparatus used comprises a two-liter volume of water enclosed by a spherical glass shell driven at its radially symmetric resonance frequencies by eight multiresonant piezoelectric transducers. Large acoustic pressures can be produced, ranging from 10 bars at 27 kc/s to 200 bars at 1.16 Mc/s. The threshold data can be divided into three regions. In region A, defined by f < 200 kc/s, acoustic pressure, P sub a < 3 bars, and air saturation pressure P sub s > 600 mm Hg, small air bubbles grow by rectified diffusion and stabilize at the pressure nodes. In region B, defined by f < 200 kc/s, P sub a > 3 bars, and P sub s < 500 mm Hg, transient cavities are formed that can be detected visually and aurally. In region C, f > 200 kc/s, P sub a > 3 bars, for any value of P sub s, transient cavities are formed, but their presence can be detected only acoustically. Experiments on cavitation at pressures larger than the threshold indicate that only a finite number of cavitation events can be produced in a given sample of water when it is isolated from contamination by airborne motes. In this way water can be strengthened by a factor of at least 8 by repeat cavitation., 21

A compilation of the unclassified Nd:YAG laser lab experiments and related analyses performed in the Laser Designator/Rangefinder Branch, Naval Weapons Center, China Lake, Calif., during the period October 1970-December 1971 is presented. The Nd:YAG laser lab was initiated by the author in October 1970 and, hence, some of the tests performed were necessarily of an introductory nature. To expedite the preparation of this report, the author's memoranda with only minor modifications are provided as appendixes.

An active experimental program began at 21 mc. with tunable circuits capable of being operated immersed or evacuated. Extensive tests were commercial 40Sn-60Pb alloy circuits to calibrate the experiment. An identical circuit coated with pure tin having a 5Sn-95Pb shield can was tested for the effects of temperature and magnetic field upon Q and resonant frequency. Residual resistance was higher than expected. A tuning slug resulted in a three fold drop in Q when fully extended. Construction of an rf amplifier continued which will be in operation at an early date. Several thin-film circuits have been successfully deposited. In parallel a technique for building foil circuits of tin, lead, tin-lead alloys, niobium, tantalum and vanadium has been developed. The alloy foils are rolled in the laboratory after mixing high purity lead and tin in proper proportions and melting. Theoretical studies continued on the transfer function of an oscillator incorporating one or two coupling probes at the tank. Calculation of inductance is nearing completion. Comparison between experimental residual resistance measurements and theory are discussed.

Thirteen model tubes were built and evaluated, the results of which are presented. Initial life test results are reported as are the results of the completed heater cycle life tests. The results of the anode evaluation program, which yielded high Q sub u, broad band, low voltage anodes, are discussed. Tubes which meet the primary electrical specifications and were delivered as the fifth and sixth engineering samples are described.

A sound source was developed which is capable of delivering continuous acoustic power into a 10-in.-diam tube at acoustic levels up to 100 kw, provided the tube temperature does not exceed 170 deg. F. An accurate and reliable condenser microphone system was developed for essentially continuous use in acoustic fields with pressure swings approaching 1 atm. Theories were developed for the attenuation of high-amplitude plane waves; however, the predicted attenuation rates were higher than those obtained experimentally. Preliminary measurements of water-spray influence on attenuation rates indicated no significant attenuation effect due to water spray and no clear evidence of frequency dependence. Measurements of the shunting impedance presented by a Helmholtz resonator placed in the 10-in.-tube wall indicated that, for an approximate 56-c low-amplitude frequency, the combination of the resonator and the downstream portion of the tube appeared resistive when the sound frequency matched the low-amplitude resonator frequency. An analysis of the standing-wave structure at this frequency for 6 particle-velocity amplitudes established that the impedance was given by R = 1/2 P rho U sub o, where P rho sub o is the equilibrium density of air, U sub o is the particle velocity amplitude, and S is the cross-sectional area of the neck of the resonator. (See also AD10268)

Studies were made controlling the frequencies of all the modes up to the second order, and investigations were made to study the electronic operation of first- and second-order modes. Experiments with operating tubes show that under given conditons, the first- and second-order modes can operate at more than 1 voltage. The different voltages can be attributed to the excitation of different Fourier components of the field configuration. Variation of resonance frequency of modes of different orders with changes in resonator parameters was studied by using a demountable resonator. It was indicated that an increase of cavity radius reduces the resonance frequency and increases the separation of the different modes; the ratio by which the resonance frequency changes for a given variation of cavity radius is smaller for the higher-order modes. An increase of radial thickness of the fingers, or a decrease of the separation between fingers, reduces the resonance frequency. A mode of separation of the order of 40% is obtained by choosing the ratio of cavity radius to anode radius to be 3:1. Sensitive control over the various modes can be obtained by introducing radial vanes in the cavity. The degenerate pairs of modes can be separated out, and the modes can be accurately located at equal intervals of the radial penetration of the vanes is chosen properly.

This report covers the first three month's activities on a program to explore the feasibility of combining two, three or more Ka-band interaction structures in cascade to produce an N-tupling of the peak and average power capability of a single stage. Activity to date has progress in two paths - analytical and mechanical. Analysis of the transmission line problems involved has determined the proper electrical design approach for the early models. Further analytical work is essential and is being pursued. The mechanical design, which involves modification of a basic Ka-band ICEM magnetron, has proceeded satisfactorily, and initial parts procurement has begun. The first hot test vehicle will be tested during the next quarterly period.