Material selection considerations for coaxial, ferrimagnetic-based nonlinear transmission lines

Abstract

The growing need for solid-state high power microwave sources has renewed interest in nonlinear transmission lines (NLTLs). This article focuses specifically on ferrimagnetic-based NLTLs in a coaxial geometry. Achieved peak powers exceed 30 MW at 30 kV incident voltage with rf power reaching 4.8 MW peak and pulse lengths ranging from 1–5 ns. The presented NLTL operates in S-band with the capability to tune the center frequency of oscillation over the entire 2–4 GHz band and bandwidths of approximately 30%, placing the NLTL into the ultra-wideband–mesoband category of microwave sources. Several nonlinear materials were tested and the relationship between NLTL performance and material parameters is discussed. In particular, the importance of the material's ferromagnetic resonance linewidth and its relationship to microwave generation is highlighted. For a specific nonlinear material, it is shown that an optimum relation between incident pulse magnitude and static bias magnitude exists. By varying the nonlinear material's bias magnetic field, active delay control was demonstrated.

Bias-field controlled phasing and power combination of gyromagnetic nonlinear transmission lines

“…The important insight from Eq. (2) is that the frequency of the generated microwaves is directly related to the field distribution inside the NLTL; therefore scaling up the size of the inner and outer conductor to increase voltage hold-off will alter the internal field, and consequently, the operating frequency. An example of this effect is the large diameter system demonstrated by Romanchenko that generates several hundred MW at a frequency 1.2 GHz.…”

“…(1) shows that the magnetic moments will precess about the magnetic field H at a frequency given by Eq. (2) which depends only on the magnetic field inside the ferrimagnetic material: [1][2][3][4] dM…”

Electrical Physical Properties of Nanostructured Ferroelectrics in Pulsed Power Electric Fields

“…In this case, if discontinuities of the solutions of equations describing electromagnetic waves propagation occur, formation of shock electromagnetic waves (SEMW) may appear [2]. Carried experimental studies [3] have shown the advantages of shock electromagnetic waves usage to obtain steep differences in waves fronts and short current impulses. When ferrites were used as a working medium of forming lines (FLs), wave fronts of the order of 1-5 ns were achieved with voltage amplitude up to 30 kV [3].…”

“…Carried experimental studies [3] have shown the advantages of shock electromagnetic waves usage to obtain steep differences in waves fronts and short current impulses. When ferrites were used as a working medium of forming lines (FLs), wave fronts of the order of 1-5 ns were achieved with voltage amplitude up to 30 kV [3]. Levels of containing ferromagnetic media FLs impulse currents amplitudes are limited because of their rather big inductance and therefore wave resistance.…”

Gyromagnetic nonlinear transmission line generator of high voltage pulses modulated at 4 GHz frequency with 1000 Hz pulse repetition rate

“…The external axial magnetic field biased (H z ) coaxial nonlinear transmission lines (NLTL) partially filled with ferrite rings were used as the sources of high-power microwave pulses [3][4][5][6][7][8][9][10]. The source rf modulation frequency was increased to 4 GHz, a fairly high output peak power of hundreds of megawatts, and operated at the maximum pulse repetition frequency (PRF) of 1000 Hz.…”