Long-Pulse Uncooled Copper Magnet for Gyrotron

The operation of a gyrotron requires a strong, stable magnetic field over time. Working in the CW mode requires complex/cryogen solenoid cooling systems. Working in the pulse mode is possible with a simple solenoid, but only for short pulses, typically up to 50 $\mu \text{s}$ . In this article, an intermediate working point for the gyrotron is presented: a pulsed gyrotron with a simple uncooled solenoid, which is capable of producing relatively long pulses of ~10 ms. To power a longer pulse with a simple solenoid, a supercapacitor (SC)-based system has been designed, which enables the extension of the operation of pulsed gyrotrons to tens of milliseconds, while keeping the system simplicity, without a cooling system for the solenoid. The setup was realized and a 27-ms current pulse of 1.1 kA was obtained through a gyrotron with a simple copper solenoid with a stability of ~0.3%. A 5-kW/10-ms radiation pulse at 28 GHz was measured from the gyrotron. This setup enables the use of a rather simple solenoid and a gyrotron and still obtains a rather long radiation pulse. This concept may open a new regime for pulsed gyrotrons.