Jin Xiaolin

Laser-driven proton acceleration using a conical nanobrush target

A conical nanobrush target is proposed to improve the total proton energy-conversion efficiency in proton beam acceleration and investigated by two-dimensional particle-in-cell (2D-PIC) simulations. Results indicate a significant enhancement of the number and energies of hot electrons through the target rear side of the conical nanobrush target. Compared with the plain target, the field increases several times. We observe enhancements of the average proton energy and total laser-proton energy conversion efficiency of 105%. This enhancement is attributed to both nanobrush and conical configurations. The proton beam is well collimated with a divergence angle less than 28{sup Degree-Sign }. The proposed target may serve as a new method for increasing laser to proton energy-conversion efficiency.

Tests of HFCS-I on calculation of attenuation characteristics of high-frequency circuits

Using HFCS-I and MAFIA, a cubic resonator and a typical helical slow-wave structure are simulated and the quality factor of the cubic resonator and the attenuation constant of the helical slow-wave structure are stressed. The results from HFCS-I and MAFIA simulation are compared in detail and they are found to be in quite agreement. Therefore, the capability of HFCS-I on calculation of high-frequency parameters, especially the attenuation characteristics of high-frequency circuits is proved.

A 2D Electron Optics System Code for Millimeter Wave Traveling-Wave Tubes

To improve the performance of the electron optics system for millimeter wave traveling-wave tubes, we developed a two-dimensional electron optics system design tool. It includes UESTCGun, UESTCPPM and UESTCMDC to model and simulate electron guns, periodic permanent magnetic focusing systems and multi-stage depressed collectors respectively. The physics models and implements of UESTCGun code, UESTCPPM code and UESTCMDC code will be presented.