The ferroelectric ceramic composition ${B a}_{{0. 8 9}} {C a}_{{0. 1 1}} {T i}_{{0. 8 7}} {Z r}_{{0. 1 3}} {O}_{{3}}$ (BCZT) was doped with Niobium, synthesized via the conventional solid-state reaction method, to investigate its structural, microstructural, and nonlinear properties for applications in nonlinear transmission lines (NLTLs). X-ray diffraction confirmed a single-phase perovskite structure for all compositions, indicating effective Nb incorporation. Scanning electron microscopy revealed high densification and significant grain size reduction with doping (from ${7} {\mu} {m}$ to ${1. 1} {\mu} {m})$, suggesting that Nb inhibits grain boundary migration. Dielectric measurements showed that Nb addition shifts the ferroelectric-paraelectric transition toward room temperature and increases the room-temperature dielectric permittivity. Tunability measurements revealed that the 0.5 mol% Nb-doped sample exhibits the highest sensitivity to the applied electric field, achieving an optimal balance between high permittivity and field response. These results demonstrate that controlled Nb-doping is an effective strategy to optimize the nonlinear performance of BCZT ceramics, making them promising candidates for NLTL-based devices.

The goal of this research is to develop a predictive model that determines how low-frequency Electromagnetic Interference (EMI) affects the leakage current behavior of CMOS transistors. Although developed and validated using NMOS devices, the modeling framework can be extended to PMOS transistors; experimental validation of PMOS devices is planned for future work. The model provides essential physical parameter-based analysis of nanoscale device EMI susceptibility during low-frequency operation. The model demonstrates high accuracy and practicality through experimental verification of test chips built with standard TSMC CMOS technology nodes. The findings highlight that modern CMOS designs must account for low-frequency EMI, which can induce leakage shifts significant enough to impact EMC compliance, functional robustness, and reliability in ultra-low-power and near-threshold applications. The research delivers a practical method for designers to evaluate and reduce EMI-induced leakage in integrated circuits.

The cooperative effort between the University of New Mexico (UNM) and the Lawrence Livermore National Laboratory (LLNL) on designing and prototyping a rectangular, sinusoidally corrugated, slow-wave structure (SWS) intended to operate in the millimeter-wave frequency range at 220 GHz is continued. The results below describe the effort toward the 220 GHz SWS design transition from the custom, not-standard rectangular-waveguide-based SWS to a standard, WR4-based SWS, abbreviated below as the WR4-SWS. The “cold” dispersion diagram of the lowest, fundamental $T E_{10}$ mode supported by the WR4-SWS is calculated by SuperFish code and the “warm” particle-in-cell simulations of the WR4 SWS driven by a $20 \mathrm{keV}, 100 \mathrm{~mA}$ electron beam are done with ICEPIC code. Results of simulations demonstrate strong, 100 W with $5 \%$ efficiency, sub-THz power generation at frequency $\sim 266 \mathrm{GHz}$ instead of the expected $\sim 220 \mathrm{GHz}$. The following analysis of both the “cold” and “warm” calculated results shows that the $20 \mathrm{keV}, 100 \mathrm{~mA}$ electron beam driving the WR4-SWS couples not the desired back-ward-traveling wave (BTW) of the $T E_{10}$ mode, but the forward-traveling wave (FTW) of the same lowest, fundamental $T E_{10}$ mode. The subsequent decision has been made to redesign the WR4-SWS into the standard, WR3-based SWS instead, or WR3-SWS.

Electromagnetic interference (EMI) has become a serious challenge for signal integrity (SI) in modern high-speed digital systems. With the technology scaling down into nanometric CMOS technologies and lowering supply voltage, EMI induced signal integrity effects are becoming more significant compared to voltage margins. This work presents experimental results of controlled RF interference affecting the eye diagrams of the CMOS inverter. The test circuits were fabricated in 65 nm, 130 nm, and 180 nm CMOS technologies. A dedicated measurement methodology has been developed to inject RF to the supply node and to capture both time domain and eye diagram signals to visualize EMI effects. Unlike previous works that analyzed effects of channel-induced impairments or presented simulation results on EMI effects, we present an experimental evaluation of the impact of EMI on circuit functionality. Experimental results reveal that EMI tends to modulate the logic-high level amplitude, causing progressive eye closure. Consistent with these results, the eye height is found to decrease monotonically with increasing RF power for all technology nodes, while the logic-low level is found to be less affected. Asymmetric CMOS inverter susceptibility is thus found to be technology independent and sensitive only to the conduction state of the inverter. To illustrate the degradation caused by EMI, a compact, analytical expression for the reduction of the eye height is derived. The reduction is given as a function of the RF interference amplitude and expressed through a technology-dependent scaling parameter. Good agreement is observed between simulated results and experiments for varying interference amplitudes and different technology generations. Results are presented to demonstrate eye height as a sensitive and reliable metric of EMI susceptibility. Additionally, a practical framework for rapid estimation of signal degradation is presented for high-speed digital systems operating in complex electromagnetic environments.

This paper demonstrates the use of full-wave electromagnetic simulations in Altair FEKO to estimate high-power (HP) breakdown margins and compares the results with predictions from a dedicated RF breakdown solver (Spark3D). Peak electric-field values are obtained from near-field simulations under normalized excitation and are used to estimate breakdown-limited power levels through square-root power scaling. OPTFEKO is also used to find the input power at which a specified electric-field breakdown level is reached by treating the source power as a variable. A straight WR-90 rectangular waveguide operating in air at X-band is used as a representative example to illustrate these capabilities and to quantify expected field levels and power limits. The results show that FEKO provides a reliable and computationally efficient tool for early HP assessment, while the comparison with Spark3D helps clarify the range of validity of field-based breakdown estimates.

UNM operates the “classic,” 1.58/2.11/4.11 A6 RM with radial output driven by the MARX generator of the PulseRad110A accelerator (Fig. 1) [1]. The operational parameters and the output characteristics of the A6 RM are monitored with the Tektronix DPO 71254C scope: Ch1 - Cathode voltage by a voltage divider, Ch2 - Discharge current by a Rogowski coil, Ch3 - Output power density by an electric field probe and a crystal detector, and Ch4 - Electric field oscillations by a “cut” WR284 waveguide(Fig. 2) whose frequency spectrum (Fig. 3(d)) is calculated by the DPO 71254C scope internally. Typical oscillograms, Ch1- Ch4, obtained at magnetic field ~3.75 kG and MARX charging voltage ±33 kV, which results in the “peak: accelerating voltage of the MARX generator $6 \times(2 \times 33 \text{kV}) \sim 400 \text{kV}$, are shown at Fig. 3

This research investigates Time-Reversal (TR) methods for detecting the resonances of passive microwave structures contained in a multipath environment. The multipath environment is realized using a reverberant, 3D, microwave cavity with irregularly-shaped metal boundary walls. The experimental setup utilized MATLAB automation to link an arbitrary waveform generator (AWG) with a real-time oscilloscope for repeated signal transmission and acquisition and TR operations inside the reverberant cavity. To demonstrate the technique, two C-band microstrip patch antennas with distinct resonant frequencies were designed, fabricated, and considered as the Device Under Test (DUT). The developed method shows that time-domain TR processing can recover the resonant response of passive structures, including both amplitude and phase information, through adaptive processing. To date, there has been no experimental validation of resonance detection utilizing time-domain TR within a deliberately wave-chaotic electromagnetic enclosure—where multipath propagation, modal overlap, and environmental loading predominantly influence the system response. The results highlight the potential of time-domain TR as a practical tool for radar sensing, passive resonance measurement, and EMI/EMC testing in complex electromagnetic environments.

A redesign of the inductively driven transmission line (IDTL) current monitor took place due to the discovery of the discrepancy between the magnetic field measurements of the two B-dots sensors. The IDTL redirects a small amount of Z's magnetic energy by passively coupling to the magnetic fields of the final power feed of the machine. The monitor is composed of a pair of B-dots oppositely oriented to measure the current that is siphoned through the secondary circuit, enabling common-mode noise cancellation. The redesign of the current monitor will not only enable the diagnostic to measure comparable magnetic fields between the two monitors but also will maintain its compact design while completing common-mode noise elimination. The discrepancy measurements of the magnetic field were identified through simulations (conducted in COMSOL Multiphysics) and calibration measurements that displayed a sensitivity difference by a factor of two. The redesigned IDTL monitor will correct this discrepancy and increase accuracy on the electrical measurements for Z experiments.

Responding to recent interest in high power microwave (HPM) sources operating in X-band, during the last three years we have successfully developed a novel type of diffraction output magnetrons (MDO) which operate in X-band (~9 GHz). Our study was based on the first X-band A8 MDO discovered by Kovalev, Fuks and others [1] in the 1970's (KF), the study of which has been abandoned until now for the sake of S-band devices. This MDO produced ~500 MW, at $\sim 9$ GHz with an electronic power efficiency of ~15% and suffered from pulse shortening. Our first slightly modified KF MDO operated at ~9 GHz with similar efficiency.[2]

The University of New Mexico (UNM) operates the “classic” 1.58/2.11/4.11 six-cavity (A6) high-voltage or relativistic magnetron (RM) driven by the PULSERAD110A pulsed power generator. The A6 RM operation, similar to any other RM, is controlled by the crossed (i) internal radial electric field, $E_{r}$, created by the cathode voltage drop, $V_{d}$, between the cathode and the anode or slowwave structure (SWS) of the A6 RM, and (ii) the external magnetic field, $B_{z}$. The measurements of the UNM A6 RM output characteristics are performed by scanning $B_{z}$ vs $V_{d}$ to define the range of $V_{d}$ within the magnetron operational domain, $V_{d}\left(B_{z}\right)$, between the Hull cutoff and the Buneman-Hartree synchronous voltages, where the “classic” A6 RM can operate in its “intrinsic” $\boldsymbol{2} \boldsymbol{\pi}$-mode at frequency $\sim 4.6 \mathrm{GHz}$. The performed $B_{z}$ vs $V_{d}$ scan also allows for calibration of the cathode voltage $V_{d}$ against the magnetic field $B_{z}$.

Radiofrequency technology is constantly evolving, and there is a continuous demand for performance improvement. Nowadays, different approaches can be used to achieve similar results. One example is the frequency multiplier, an electronic system fed by a radiofrequency (RF) source that can generate output frequencies higher than the input frequency, in some cases hundreds of GHz [1]. For high-power applications, this system can be integrated with a Traveling Wave Tube (TWT) to achieve simultaneous high-frequency and high-power operation.

Metamaterials are artificially constructed subwavelength structures that have exotic physical properties that cannot be realized or are difficult to realize with natural materials. Hence, the creative introduction of metamaterials into vacuum electron devices (VEDs) has led to their novel performance with characteristics such as small size, low weight, high power, high efficiency, or high gain. The use of transformative technologies will facilitate their development from laboratory demonstrations to industrial deployment.

The A6 magnetron is the most successful and most studied relativistic magnetron (RM) invented at MIT by George Bekefi et al. [1]. The resonant system of the A6 magnetron consists of six identical sectoral cavities of angular width 20°, an axial length 7.2 cm, anode radius $\mathrm{r}_{\mathrm{a}}=2.11$ cm cavity radius $\mathrm{r}_{\text {cav }}=4.11 \text{cm}$, and radius of the solid cathode $\mathrm{r}_{\mathrm{c}}=1.58 \text{cm}$. Most conventional magnetrons are designed to oscillate in $\pi$-mode $(\mathrm{n}=3)$. For this mode the RF electric fields in adjacent resonators are 180° out-of-phase with one another. The A6 magnetron oscillates preferentially in the $2 \pi$ mode $(\mathrm{n}=6)$, which is characterized by the fact that the RF fields of all resonators are precisely in phase.

Ferroelectric ceramics can be used as nonlinear capacitors in nonlinear transmission lines (NLTLs) to generate radio frequency with applications in defense systems and pulsed radars. Their primary feature is their nonlinear behavior, which is the variation in capacitance with temperature and electric field. One crucial ceramic material for these uses is barium titanate (BT). The ceramic paraelectric phase, however, is above the Curie temperature of 120 C-degrees in its pure form. We synthesized and studied the Ba(1-x)Sr(x)(Zr0.2Ti0.8)O-3 ceramic as a nonlinear element by downshifting the paraelectric to ferroelectric phase transition close to ambient temperature to enhance the nonlinear characteristics. By varying the frequency and applied electric field, we examined the capacitance behavior of this material. Additionally, we discovered that this ceramic composite's paraelectric phase transition occurred at a concentration of x = 0.5% strontium. To illustrate the RF generation, we constructed and tested a nonlinear LC circuit employing ten ceramic samples that contained 0.5% strontium as nonlinear capacitors. Finally, we estimated the RF frequency generated to be 5.4 MHz by deriving expressions for the propagating solitary-wave solution, which agrees with the experimentally determined value.

Results of Particle in Cell simulations of an optimized design of a diffraction output relativistic A8 magnetron operating as a high power microwave (HPM) source in X-band (8.77 GHz) are presented. In addition to the very high efficiency of ∼80%, this design reveals a unique property, that is, for magnetic fields significantly exceeding the Hull cutoff condition, a quasiperiodic train of HPM pulses appears with instantaneous peak power above the steady state input power amplitude. This phenomenon is described, analyzed, and explained.

Fusion energy meets the twenty-first century World Grand Challenge of sustainable, ubiquitous, and safer energy sources. However, harnessing the promise of fusion energy has proven elusive. The competing approaches to fusion power plant design include inertial confinement fusion, National Ignition Facility (ICF-NIF, Z machine, etc.,) magnetic confinement fusion (MCF-Tokamak, stellarators, etc.), and other approaches that show promise in small- (flow stabilized Z pinches) or large-scale applications. These approaches are being accelerated with private and public funding and seek to demonstrate the feasibility of different approaches to fusion-based power plants. Yet, how can the necessary pulsed power technologies for these disruptive technology bases be accelerated with no clear “Dominant Design?” Roadmapping holds the promise to identify and develop common critical pulsed power components for laboratory, prototype, and commercial fusion, and can accelerate the commercialization of fusion reactor designs. A preroadmapping Workshop on Pulsed Power for Fusion was held at the IEEE International Pulsed Power Conference in San Antonio, TX, USA, in June 2023. The workshop had 177 attendees. Here, the common elements for many of the ICF technologies vying for dominant design were identified. The advancement of these technologies through roadmapping will enhance commercial expectations that require their rapid and innovative development in the next five years, as well as the next five to ten years. The key technologies identified that underpin and limit the advancement of fusion power include pulsed power technologies such as energy storage, high-voltage switching, additive manufacturing, and modular pulsed power circuit topologies. They are the focus of our effort in the following roadmap scenario, which will delineate potential paths to technology development.

An A10 relativistic magnetron with a diffraction output (MDO), similar to an A8 MDO operating at similar to 8.8 GHz investigated in recent publications, is studied using 3-D particle in cell (3-D PIC) simulations. This MDO operates at similar to 9.8 GHz, closer to the frequency of interest, and reaches high power and high efficiency. At high magnetic field values, considerably above the Hull limit, its amplitude consists of slow (relative to the operating frequency) power modulations with amplitudes reaching twice that of the corresponding input power with no evident mode competition and without violating energy conservation. This feature has been revealed for the A8 magnetron and explained by the dynamics of the longitudinal motion of the excess electron charge oscillating in the potential well bounded by two conducting reflectors (cathode endcaps). This mechanism is also supported by the present results.