Subjects: Physics >> Nuclear Physics submitted time 2023-06-09 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: To implement the Tsinghua Thomson Scattering X-ray Source (TTX) upgrade plan and the Very Compact Inverse Compton Scattering Gamma-ray Source (VIGAS) program, a new 1.5-m traveling-wave accelerating structure was designed to replace the old 3-m SLAC-type structure with the aim of increasing the accelerating gradient from 15 to 30 MV/m. The new type of structure works in the 3π/4 mode with a comparatively low group velocity varying from 0.007c to 0.003c to increase the accelerating gradient at a given power. An elliptical iris was employed to reduce the surface field enhancement. The filling process of the low-group-velocity structure was analyzed using a circuit model. After fabrication, the structure was precisely tuned using the non-contact tuning method, followed by detailed low-power radiofrequency measurements. The structure was first installed and utilized at a beamline for the Terahertz experiment at Tsinghua University. After 120 h of conditioning, it is now operating at a gradient of 24.2 MV/m and a 20.7-MW input power, with the klystron operating at its full power. It is expected to generate an accelerating gradient of 30 MV/m when the klystron power is upgraded to 31 MW in the near future.
Subjects: Physics >> Nuclear Physics submitted time 2024-01-18
Abstract: Very high-energy electrons (VHEE) are potential candidates for FLASH radiotherapy for deep-seated tumors. We proposed a compact VHEE facility based on an X-band high-gradient high-power technique. In this study, we investigated and realized the first X-band backward traveling wave (BTW) accelerating structure as the buncher for a VHEE facility. A method for calculating the parameters of single cells from the field distribution was introduced to simplify the design of the BTW structure. Time-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state. A prototype of the BTW structure with a thermionic-cathode diode electron gun was designed, fabricated, and tested at high power at the Tsinghua X-band High-power test stand. The structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: A test system is developed for the BESIII ETOF/MRPC beam tests of data acquisition, environment monitoring and automatic control. The software framework is based on the CAMAC bus, VME bus and Serial Port, which are responsible for communications with the detectors. The monitor system works well in the beam test.