The inhomogeneously-loaded helical slow-wave structure is field analyzed by azimuthally smoothing out the discrete supports into a number of continuous dielectric tube regions appropriate permittivity values. analysis made rigorous removing usual approximation considering radial propagation constant to be same in different regions; moreover, tape-helix instead simpler sheath-helix model has been used consider space-harmonic effects. This renders present more general, accurate and capable...

Space traveling wave tubes (TWTs), which are used in satellite communications, need to be compact and light weight, have high overall efficiency. In a typical TWT, ~45% of the weight is due collector, normally made bulkier dissipate waste heat. Hence, reduction size collector will lead huge savings entire thereby impacting significantly on launch cost satellite. However, has several associated bottlenecks challenges. Here, we successfully addressed those challenges developed novel, compact,...

A nonresonant perturbation (NRP) theory is developed from first principles for the measurement of dispersion and interaction impedance characteristics a helical slow-wave structure (SWS). The phase reflected signal test varies when perturber, also in form helix, moved along axis structure. variation with perturber position interpreted to find velocity under test. found by measuring change axial phase-propagation constant as dielectric rod placed Measurements are carried out help an automated...

Continuous device downscaling, growing integration densities of the nanoscale electronics and development alternative information processing paradigms, such as spintronics quantum computing, call for drastic increase in data storage capacity. In this paper we review our recent results design, fabrication characterization near-field optical transducer heat-assisted magnetic recording beyond 10-Tbit/in 2 densities. order to record information, system uses not only but also thermal energy. For...

Multistage depressed collectors (MDCs) are used to enhance the overall efficiency of travelling-wave tubes (TWTs). Thermal management is one critical concerns when such TWTs for space application. In this paper, authors have presented an innovative technological concept develop a typical four stage MDC in single ceramic better thermal management. Here, multiple brazing joints been reduced, which, turn, reduces contact resistances (TCRs) and thereby improves than its conventional counterpart,...

A dual-anode convergent electron gun with a perveance of 0.14 μp has been designed and developed for high-efficiency helix traveling-wave tube (TWT), which would ultimately have application in satellite communication system. The an isolated beam forming electrode M-type dispenser cathode 3.1-mm button diameter using EGUN, OMNITRAK-3-D, OPERA-3-D codes. It consists two anodes, namely, control anode ion-barrier anode, addition to ground accelerating meet the requirement long life high...

Asymmetric multistage depressed collectors (MDCs) are preferred in traveling wave tubes due to their high performance terms of collector efficiency and low back-streaming current. However, the main drawbacks associated with these asymmetric MDCs difficulty fabrication often bulkier size, as it generally requires an additional magnet or pole piece. Here, we have designed developed MDC, where asymmetry electric field has been achieved by suitable electrode geometry modification. Furthermore,...

Radiation-cooled helix traveling-wave tube (TWT) is mostly used as a high-power microwave amplifier in satellite communication. The radiation shield assembly has to fit on the multistage depressed collector (MDC) radiate waste heat into space environment and demands efficient thermal modeling. In this work, been designed with dissipation capacity of 100 W. Moreover, withstand mechanical vibration faced during launching. article, author proposed detailed design analysis cooling for TWT,...

The boundary layer flow of a steady incompressible and visco-elastic fluid with short memory (obeying Walters’ B model) passing over hot vertical porous plate has been investigated in the presence transverse magnetic field. momentum energy equations are reduced to couple non-linear partial differential along conditions by using suitable similarity transformation. These transformed system coupled ordinary employing perturbation technique. is solved developing numerical procedure such as...

An analysis to determine performance parameters for dispersion characteristics and interaction impedance of helix traveling-wave tube using metamaterial is presented. The conventional positive dielectric supports the slow-wave structure have been replaced by an equivalent homogeneous medium. has carried out in tape model, include effects space harmonics. Structure characteristics, namely, studied, as former predicts phase velocity RF wave latter direct relevance device gain. It observed...

Travelling wave tube (TWT) is a broadband vacuum microwave devices used as high power amplifier in satellite for communication. Thermal management of space TWT one the key aspects influencing its reliability, efficiency and life. The performance have relevance to heat distribution thermal equilibrium condition. multi-stage depressed collector (MDC) bulkiest part with highest load demand efficient management. In paper author presented estimation using energy balance principal compared...

In this article, a thin wire (TW) metamaterial (MTM)-based interaction structure has been reported as potential candidate for realizing backward wave oscillator (BWO). The designed by arranging an array of connected TWs periodically along the axis hollow rectangular waveguide. TW exhibits negative permittivity transverse dimensions and allows mode propagation below magnetic (TM) cutoff Two variants, one with wires square cross section (STW) other circular (CTW), have considered. frequency...

Multistage depressed collectors (MDCs) play a vital role in efficiency enhancement of traveling-wave tubes for various strategic and communication applications. Design highly efficient MDC is no longer tough challenge due to the availability large number numerical simulation tools. However, still an established technique development such MDCs address their thermal as well high-voltage breakdown issues has not been published. In this paper, we have exercised different techniques light...

The propagation of electromagnetic waves in a plasma-filled cylindrical waveguide the presence constant external magnetic field is investigated using warm plasma theory. It found that cannot be separated into transverse and electric modes; only hybrid modes are propagated. Dispersion relations derived for zero, finite infinite fields. Frequency shifts wave case small calculated.

In a travelling wave tube, much of the waste power is dumped into collector. If heat not properly managed, it might pose serious problem causing even failure tube. this paper, optimal choice thermal management highly efficient multistage depressed collector designed for space TWT has been made based on several criteria. The structural deformations and stresses developed due to impact have evaluated. influence electrical performance high voltage withstanding capability studied during hot condition.

The slow-wave structure parameters of a traveling-wave tube with T-shaped dielectric rods in metal envelope were optimized for flat-to-negative dispersion characteristics obtained by the sheath-helix model analysis. analytical results validated against those tape-helix analysis and CST Microwave Studio. Such also gave wideband gain–frequency response device as predicted Pierce’s small-signal theory. electron beam voltage was identified an additional parameter widening bandwidth.

Attaining good collector performance in terms of high efficiency, low backstreaming, and body interception current has been a prime motive for traveling wave tube (TWT) designers. Selection appropriate electrode material can result enhancement the same electrical design (with potentials geometry). Here, attempts have made to quantitatively demonstrate unexplored impact selection on systematically. The effect backstreaming current, their fluctuations arising practical scenario due variations...