No abstract available

[en] As the ceramic window of the waveguide transmission system of a medical electron-accelerator cracked and F₁₂ gas leaked into its vacuum system, some verdigris was found to contaminate the internal surface of the accelerating tube. The X-ray diffraction analysis indicates that the verdigris consists of CuCl·3[Cu(OH)₂[ predominately and CuCl. The causes of forming verdigris are discussed. It seems that any kinds of isolation gas leaked into the vacuum system can be ionized and then corrode the copper surface. Various possible reasons for causing cracks on the ceramic window are cited and some preventive measures are suggested

No abstract available

[en] A travelling wave reaonant-ring was constructed for RF window high power test of NSRL 200 MeV linac. The principle of the resonant-ring was described. A power gain of 4.5 and a peak power of 60 MW were achieved in the ring. The power test method and procedure were given out, and the electron multiple effect was discussed. The RF window passed test under the conditions of a peak power of 30 MW, an average power of 3.7 kW and a pulse length of 2.5 μs. (authors)

[en] By using the computer image processing technology and RF phase auto-shifting system, the ESS (Energy Stabilization System) was applied to 200 MeV Linac. the ESS adjusts beam energy automatically in a range of +-4 MeV. After adjustment beam energy stability is improved to +-6%

[en] The authors have derived the global band gaps for general two-dimensional (2D) photonic crystal microwave accelerating structures formed by square or triangular arrays of metal posts. A coordinate-space, finite-difference code was used to calculate the complete dispersion curves for the lattices. The fundamental and higher frequency global photonic band gaps were determined numerically. The structure formed by triangular arrays of metal posts with a missing rod at the center has advantages of higher-order-modes (HOM) suppression and main mode restriction under the condition of a/b<0.2. The relationship between the RF properties and the geometrical parameters have been studied for the 9.37 GHz photonic crystal accelerating structure. The Rs, Q, Rs/Q of the new structure may be comparable to the disk-loaded accelerating structure. (authors)

[en] An X-band detuned accelerator structure was designed using the Mafia code and the parameters were calculated efficiently through the Lagrange interpolation method, then the characteristics and wakefield of this structure were obtained in the end. The results indicate that this structure not only has high quality factor and high shunt impedance, but also can suppress the wakefield to decrease significantly to a low level comparing with the constant impedance accelerator structure, so that the probability of beam break-up is reduced to a great extent

[en] Corrosion and leak happened at brazing of a beam current monitor (BCM) under the radiation environment of linac and transport line. Corrosion products were analyzed with a rotating anode X-ray diffractometer, and Fe₂F₅·7H₂O, CuF₂·2H₂O and CuF₂ were identified. They are believed to be the compounds of gas and metal ions at brazing with F^- from Teflon that is decomposed by radiation

No abstract available

[en] By introducing photonic crystal (or PBG) structure to the traditional disk-loaded accelerating tube, wakefields in the accelerating structure can be effectively damped. Machining methods of a 2D metallic PBG cavity were investigated and X-band PBG cavities with high quality factor were successfully fabricated. Suppression brought by the absorbers placed at the periphery of these PBG accelerating cavities is significant to the high order modes, but has very little effect on the accelerating mode TM₀₁-like. Design and fabrication of a 4-cell traveling wave accelerating structure operating at the frequency of 11.42 GHz were accomplished and the cold test results were in agreement with the numerical simulations. (authors)