Abstract
The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a $Z$-pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array $Z$-pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%--90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is $32\text{ }\text{ }\mathrm{cm}/\ensuremath{\mu}\mathrm{s}$ when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%--30%, providing a high efficient facility for research on the fast $Z$ pinch and technologies for repetition-rate-operated accelerators.
Highlights
The fast Z pinch offers an efficient means to generate high-power soft x-ray radiation that can be employed to energize a hohlraum for inertial confinement fusion [1,2,3]
Facilities based on traditional Marx generators and waterline technologies, such as Saturn [4] and Z [5] [both located at Sandia National Laboratories (SNL)] and primary test stand (PTS) [6] [in China Academy of Engineering Physics (CAEP)], can deliver current rising to up to tens of megaamperes in ∼100 ns into a wire-array Z-pinch load, driving it to implode and stagnate on the axis by the pinch effect
The novel trigger utilizing a single input trigger pulse is proved to be a success, which shows great promise for applications on future large current accelerators to reduce the difficulty in trigger systems. (ii) Based on the architecture of the prototype cavity, we have developed a design for a Z-pinch accelerator composed of six modules, each consisting of eight stacked annular LTD cavities in a voltage-adding configuration
Summary
The fast Z pinch offers an efficient means to generate high-power soft x-ray radiation that can be employed to energize a hohlraum for inertial confinement fusion [1,2,3]. The stagnation process enables a conversion efficiency of up to 15% from the stored electrical energy to radiation [7]. This high efficiency provides a strong motivation for the pursuit of relevant technologies, such as the lineartransformer-driver (LTD), which was initiated by the High Current Electron Institute (HCEI) in Russia [8,9,10,11,12,13,14].
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