To meet the switching requirements of high-frequency pulse power systems and further enhance the peak power and turn-on speed of solid-state switches, comparative experimental studies were conducted on the structure of optically controlled multi-gate thyristors and the parameters of injected light. The research found that semiconductor chips based on the multi-gate thyristor structure exhibited different conduction characteristics under varying laser injection conditions, resulting in unique inflection point curves. By establishing a switching model and varying the injected light parameters and circuit parameter models, three conceptual operating modes for the optically controlled multi-gate thyristor were proposed: photonic linear mode (Mode A), field-induced nonlinear mode (Mode C), and hybrid amplification mode (Mode B).
Based on these concepts, experimental validation tests were conducted, confirming the three distinct operating characteristics of the optically controlled multi-gate thyristor. In Mode A, the conduction process is primarily related to the injected light power parameters and is similar to the linear mode of traditional light-guided switches, making it suitable for narrow pulse width applications. Mode C mainly focuses on carrier multiplication after injection, resembling the conduction characteristics of super thyristors (SGTO), and is suitable for wide pulse widths and high current applications. Mode B's initial conduction is related to the injected light parameters, while the later carrier multiplication continues from the earlier photonic linear mode, achieving characteristics of both fast rise time and wide pulse width, effectively combining the advantages of light-guided switches and SGTOs.
In Mode A, with an injected laser energy of 8.5 mJ, pulse width of 10 ns, and peak power of 0.85 MW, the switch operates at a voltage of 5.2 kV, an output current of 8.1 kA, a turn-on time (10%-90%) of 18.4 ns, and a di/dt value reaching 440 kA/μs. The main characteristic is that the di/dt of the switch is linearly related to the injected laser energy, allowing for fast rise time output, which reflects the photonic linear conduction mode. This mode is suitable for high-power, narrow pulse, and fast rise time applications, such as high-power microwave sources, with characteristics similar to gas switches.
In Mode C, with a triggering laser energy set at 250 μJ, pulse width of 210 ns, and peak power of 1200 W, the switch operates at a voltage of 8.5 kV, with a short-circuit current reaching 6 kA and a current rise time of 110 ns, achieving a di/dt value exceeding 55 kA/μs. The key characteristic is that the di/dt of the switch is unrelated to the injected laser energy but is related to the electric field applied across the switch, enabling operation with large current and wide pulse width, which reflects the field-induced nonlinear conduction mode. This mode is suitable for high-power, wide pulse, and slower rise time applications, such as large current detonation and electromagnetic drives, with characteristics similar to igniter tubes and triggered light.
In Mode B, with a triggering laser energy set at 10 mJ, pulse width of 20 ns, and peak power of 0.5 MW, the switch operates at a voltage of 4.6 kV, with a short-circuit current reaching 8.5 kA and a current rise time of 66 ns, achieving a di/dt value exceeding 129 kA/μs. The main characteristic is that the initial conduction of the switch satisfies the photonic linear conduction mode, while the later conduction exhibits the field-induced nonlinear conduction mode, thus achieving both fast rise time output and the capability for large current and wide pulse width, reflecting a hybrid conduction mode. This mode is suitable for high-power, wide pulse applications, such as accelerator power supplies, with characteristics similar to hydrogen thyratrons and pseudo-spark switches.
The discovery and validation of multiple operating modes for the switch significantly enhance the di/dt and peak power of power semiconductor switching devices, laying a theoretical and experimental foundation for the development of semiconductor switches with ultra-high peak power. Additionally, the switching devices were packaged according to their different operating modes and applied in accelerator power supplies, solid-state detonators, and high-stability pulse drive sources, yielding positive results.