Fault locating for traveling-wave accelerators based on transmission line theory

Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power beams.Compared with commonly used schemes involving dedicated devices or complicated techniques,a convenient approach for breakdown locating based on transmission line(TL)theory offers advantages in the typical constant-gradient TW-accelerating structure.To deliver such an approach,an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fun-damental theory of the TL transient response in the time domain.An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations.Furthermore,to validate the proposed fault-locating method in practical applications,an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology.In addition,further considerations and discussion for extending the applications of the proposed method have been given.This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supple-ment to existing methods,facilitating solution to construction problems at an affordable cost.

Comparative brain pharmacokinetic study of Jiaotai Pills in normal and insomnic rats using brain microdialysis combinated with LC–MS/MS

Objective：To compare the brain pharmacokinetics of five protoberberine-type alkaloids（i.e.berberine,palmatine,coptisine,epiberberine,and jatrorrhizine）,which were the main bioactive constituents of Jiaotai Pills（JTP）,in normal and insomnic rats orally administrated with JTP.Methods：The detection was conducted by a fully validated liquid chromatography-tandem mass spectrometry combinated with brain microdialysis method.Brain microdialysis probes were inserted into the hippocampus of rats.JTP extracts were administrated intragastrically and then brain microdialysates were collected at 30 min time intervals for 10 h.The separation of the five protoberberine-type alkaloids was carried out on a BDS Hypersilusing a mobile phase consisting of acetonitrile and water（containing 5 mmol ammonium acetate adjusted to p H 5.0）within 4 min.The quantification was performed by multiple reaction monitoring with the transitions of m/z 336.0-320.1 for berberine,m/z 352.0-336.1for palmatine,m/z 338.0-322.1 for jatrorrhizine,m/z 336.0-320.1 for epiberberine,m/z 320.0-292.1 for coptisine and m/z 356.4-192.1 for IS.Results：The lower limit of quantification for five protoberberine-type alkaloids was 0.05 ng/m L.Linearity,accuracy,precision,stability and matrix effect of five analytes were all satisfactory.Five protoberberinetype alkaloids were quickly distributed in the brain.Moreover,significant differences in the principal pharmacokinetic parameters such as AUC andthe analytes were observed between two groups.Conclusion：The LC-MS/MS method combinated with microdialysis is useful in the brain pharmacokinetic study of five protoberberine-type alkaloids.The results indicated that the rates of analytes absorption in insomnic rats were significantly higher than those in normal rats.Besides,the protoberberine-type alkaloids could bring a direct effect on the neuron in the hippocampus.