Zhang Linwen

A lattice scenario for a proton radiography accelerator

A proton radiography system is an accelerator-based facility. Especially high-energy proton radiography is an advanced hydrodynamics diagnostic tool, and it is the trend of radiography technology development. In this paper, a 20 GeV accelerator complex scenario, including a 35 MeV linac, a 1 GeV booster and a 20 GeV main ring, is introduced. The overall physics design of the proton radiography accelerator is described, including the design of each part of the accelerator and the choice of the main parameters.

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process.

Vacuum Outgassing Behavior of Carbon Nanotube Cathode with High-Intensity Pulsed Electron Emission

Experimental investigations on the vacuum outgassing of a carbon nanotube (CNT) cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV diode voltage, the CNT cathode could provide 1.67 kA electron beam with the amount of outgassing of about 0.51 PaL. It is found that the amount of outgassing, which determines the cathode emission current, depends on the diode voltage and the vacuum.

Alignment techniques for DRAGON-I LIA

DRAGON-I designed and manufactured by CAEP is a linear induction accelerator which can produce a 20 MeV-3 kA-60 ns electron beam. The high performance required for the machine is determined by the beam quality and thus is greatly dependent on the accelerator alignment. In order to reduce the chromatic effect of the beam, the stretched wire technique has been developed to measure magnetic axes of the cells precisely, and the dipole steering magnets have been equipped into each cell to correct its magnetic axis misalignment. Finally, the laser tracker has been used to examine the installation error of the accelerator. In this paper, different alignment techniques and the primary results are presented and discussed.

PPPS-2013: This is a sample abstract submission development of MHZ rep-rate linear induction accelerator at burst mode

MHz Rep-rate linear induction accelerator has many important applications in flash X-ray radiography, high power microwave and so on. Many key technologies for MHz rep-rate linear induction accelerator such as novel pulsed power technologies to generate MHz rep-rate high voltage pulses and design of the induction cavity working at MHz rep-rate at burst mode, MHz rep-rate emission cathode have been proposed and developed at Institute of Fluid Physics. A new linear induction accelerator working at MHz rep-rate at burst mode is under development at IFP. The most recent progress will be introduced in the paper.

Design and Experiment of a 600 kV V/N Switch

A V/N switch for a multi-pulse generator has been designed, constructed and tested. The switch, using a spark gap to isolate triggered pulse and a multi-stage triggered electrode to cause the breakdown more quickly, can work at 600 kV with the time jitter less than 2 ns and the rising time less than 20 ns. Compared to other types of pulsed high-voltage switch, the N/V switch can operated stably by using triggered pulse with a relatively lower voltage and at lower cost. However, under specific circumstance, performance of the switch deteriorates, which is also discussed in this paper.

High-voltage characterization for the prototype induction cells

Two linear induction prototype cells expected to work at 250kV, 3kA, with accelerating voltage flattop (±1%) ≥70ns, have been tested to determine their high-voltage characteristics. Each cell is composed of a ferrite core immersed in oil, a gap with curved stainless steel electrodes, a solenoid magnet, and a insulator. The experiments were carried out with full-scale cells. The high voltage pulses were applied to two cells using a 100ns, 12Ω pulse Blumlein. The tests were performed at various high-voltage levels ranging from − 250kV to −350kV. No breakdown was observed during the test at vacuum level (7–10) ·10−4 Pa. The cell schematic, the experimental set up, and the measured voltage waveforms are presented in this paper.