Jiang Xiaofeng

A Multi-Gap Multi-Channel Gas Switch for the Linear Transformer Driver

A multi-gap and multi-channel gas switch with convexo-convex discal planet electrodes was designed and investigated. Eight gaps are formed in series by a trigger electrode, six intermediate electrodes and two high voltage electrodes with a uniform gap length of 5 mm. The self breakdown and triggered breakdown performance of the switch are reported. Both the delay time and jitter decrease with the increase in the trigger voltage, switching coefficient and the decrease in the trigger isolating resistor. The delay time of the switch is about 40 ns, and the jitter is less than 2 ns when charged with ±85 kV and triggered by a voltage pule of −75 kV. The inductance of the switch is about 30 nH.

Test of a single stage 1-MV prototype induction voltage cavity

A single stage 1-MV prototype induction voltage cavity has been tested detailedly. Low-voltage principle experiments with injection currents of several kiloampere, and high-voltage experiments with feed pulses up to 800 kV/150 kA have been conducted. The major objective of the principle experiments is to measure the feed current symmetry. With the cavity fed by a single current, azimuthal distributions of feed currents under several typical azimuthal line configurations are measured. Meanwhile, the influence of the current asymmetry on cavity equivalent inductance is analyzed. With the cavity fed by double currents, the effects of asynchronous feed currents on current symmetry and current addition efficiency are investigated experimentally. When the cavity is single-point driven by high-power pulses, the insulator stack made of three different dielectrics is tested. The results show that the final flashover voltage of the two newly developed materials is slightly higher than that of the common PMMA.

Trigger method based on internal bricks within cavities for Linear Transformer Drivers

A novel trigger method based on an internal brick and azimuthal line in cavities is presented for Linear Transformer Drivers (LTD). The triggered brick is similar as the other normal bricks in cavities, which has the same charge voltage and the switch gas pressure. When the switch in triggered brick is closed by an external pulse, a high voltage pulse is produced and transmitted to other bricks along an azimuthal line installed in the middle insulator of cavities. Therefore, one external trigger pulse is enough for a 1 MA LTD cavity. This novel trigger manner has been applied successfully in 800 kA cavity with 36 bricks. Based on this novel trigger manner, a trigger method is proposed for a LTD module with multi-stage cavities stacked in series. Only several upstream cavities are triggered by external trigger pulses, and the residual cavities are triggered by the high pulses produced from the particular-location of upstream cavities. This trigger method will greatly simplify the requirements of trigger system, which has a promising application for future 60-MA LTD accelerator.

200kV Multi-gap Multi-channel Gas Spark Switch for Fast Linear Transformer Driver

Modular linear transformer driver (LTD) is a novel fast discharge high power pulse current source on primary storage energy. It can realize many LTD modules in series or parallel connection conveniently and can directly acquire the rise time of 100~200 ns of high power pulsed current. The switch is one of the pivotal components of the LTD. The multigap multichannel gas spark switch has the advantage of low inductance and stabilization. This paper introduced a multigap multichannel gas spark switch used to fast LTD module with the current rise time of 100 ns, and the current peak of 100 kA. The electric field analysis of the switch is carried out for switch design. The experimental results of static and transient property show that the switch with low inductance and finer stabilization is good enough to work for the designed fast LTD module.