Microwave Tube Research & Development Centre

The militarization of space has accelerated, necessitating advanced defense technologies to ensure strategic dominance. Space-based Directed Energy Weapons (DEWs), including High-Energy Lasers (HELs) and High-Power Microwave (HPM) systems, offer precision targeting, rapid engagement, and minimal collateral damage while ensuring electromagnetic superiority. However, their feasibility is constrained by power generation limitations, energy storage, beam control, and environmental factors such as ionospheric interference and heat dissipation in microgravity. This paper examines the technical challenges of deploying DEWs in space, analyzing solutions such as space-based solar power, high-density capacitors, superconducting batteries, and AI-driven adaptive optics to enhance operational reliability. Beyond technological considerations, this study explores the geopolitical, legal, and ethical implications of space-based DEWs, including compliance with international treaties, risks of conflict escalation, and the strategic consequences of space weaponization. To mitigate these concerns, this paper outlines regulatory frameworks, fail-safe engagement protocols, and multi-domain integration strategies for responsible deployment. By integrating technological advancements with strategic policy measures, this study provides a framework for the future incorporation of DEWs in space-based defense while addressing the risks and challenges associated with their implementation.

Double perovskite materials have emerged as key players in the realm of advanced materials due to their unique structural and functional properties. This research mainly focuses on the synthesis and comprehensive characterization of Ba2CoWO6 double perovskite nanopowders utilizing a high-temperature conventional solid-state reaction technique. The successful formation of Ba2CoWO6 powders was confirmed through detailed analysis employing advanced characterization techniques. Rietveld refinement of X-ray diffraction (XRD) and Raman data established that Ba2CoWO6 crystallizes in a cubic crystal structure with the space group Fm-3m, indicative of a highly ordered perovskite lattice. The typical crystallite size, approximately 65 nm, highlights the nanocrystalline nature of the material. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) discovered a distinctive morphology characterized by spherical shaped particles, suggesting a complex particle formation process influenced by synthesis conditions. To probe the electronic structure, X-ray Photoelectron Spectroscopy (XPS) identified cobalt and tungsten valence states, critical for understanding dielectric properties associated with localized charge carriers. The semiconducting character of the synthesized Ba2CoWO6 nanocrystalline material was confirmed through UV-Visible analysis, which revealed an energy bandgap value of 3.3 eV, which aligns well with the theoretical predictions, indicating the accuracy and reliability of the experimental results. The photoluminescence spectrum exhibited two distinct emissions in the blue-green region. These emissions were attributed to the transitions 3P0→3H4, 3P0→3H5, and 3P0→3H6, primarily resulting from the contributions of Ba2+ ions. The dielectric characteristics of the compound were analyzed across a different range of frequencies, spanning from 1 kHz to 1 MHz. Magnetic characterization using Vibrating Sample Magnetometry (VSM) revealed antiferromagnetic behavior of Ba2CoWO6 ceramics at room temperature, attributed to super-exchange interactions between Co3+ and W5+ ions mediated by oxygen ions in the perovskite lattice. Additionally, first-principles calculations based on the Generalized Gradient Approximation (GGA+U) with a modified Becke–Johnson (mBJ) potential were employed to gain a deeper understanding of the structural and electronic properties of the materials. This approach involved systematically varying the Hubbard U parameter to optimize the description of electron correlation effects. These results deliver an extensive understanding of the structural, optical, morphological, electronic, and magnetic properties of Ba2CoWO6 ceramics, underscoring their potential for electronic and magnetic device applications.

ABSTRACT Micro-machining involves the removal of small amounts of material by action other than that of a sharp-edged tool. The most common technique being electrical discharge machining (EDM). The material removal rate and edge definition of the finished product are based on different process parameters. This study is aimed to characterise micro-EDM process parameters for tungsten–copper and to achieve maximum material removal rate without affecting the edge definition and surface roughness while using smaller electrodes. Eight process parameters were studied for their influence on the material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). Taguchi design of experiments was carried for 36 experimental runs. The ANOVA analysis showed that the MRR depends largely on voltage, energy and current, while the TWR depends on the energy and voltage. The surface roughness value (Ra) was influenced more by energy, incremental depth and the pulse width, thus differing from MRR and TWR. The optimum parameter set for higher MRR (10e-3 mm3/min) and lower Ra (0.13 µm) was deduced from regression analysis, and the confirmation tests showed less than 8 % deviation from the predicted values. The SEM studies showed greater depths of craters in the surface machined for higher MRR.

Design and analysis of ferrule-loaded folded waveguide slow wave structure is carried out for a high-power millimeter-wave traveling-wave tube (TWT). The design of the structure is carried out by numerical simulation. A typical structure has been designed and fabricated at the Ka-band, and cold test measurement is carried out for the cold circuit parameters and the results are compared against numerical analysis. To compare the efficacy of the ferrule-loaded folded waveguide structure, a conventional folded waveguide structure is also designed for the same operating bandwidth, and cold circuit parameters are compared. The comparison results shows that the interaction impedance of the ferrule-loaded folded waveguide structure is double compared with the conventional structure at the cost of reduction in cold bandwidth. Furthermore, particle-in-cell (PIC) simulation is also carried out to estimate the output power and gain for both the structures for the same operating band, and the results are compared. The comparison results show that the cross section is reduced by 22% and the overall interaction length is reduced by 50% for the ferrule-loaded FW-SWS compared with the conventional FW-SWS for the same output power of about 500 W.

In this paper we discuss the design of Magnetic focusing system (MFS) for a compact helix travelling wave tube (TWT) operating in Ka-band. Issues related to the design of the magnetic focusing system have been discussed in detail along with practical measurement results. The key design parameters considered for this TWT are: the cathode voltage is around 9.3kV, beam current is 200mA and total length of the tube not more than 6 inch with minimal weight.