Design and commissioning of a wideband RF system for CSNS-Ⅱ rapid-cycling synchrotron

The China Spallation Neutron Source(CSNS) upgrade project(CSNS-Ⅱ) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect in rapid-cycling synchrotrons owing to the increased beam intensity. To satisfy the requirements of dual-harmonic acceleration, a new radiofrequency(RF) system based on a magnetic alloy-loaded cavity is proposed. This paper presents design considerations and experimental results regarding the performance evaluation of the proposed RF system through high-power tests and beam commissioning. The test results demonstrate that the RF system satisfies the desired specifications and affords significant benefits for CSNS-Ⅱ.

Study of the gas sources of the Ordovician gas reservoir in the Central-Eastern Ordos Basin

The source of the natural gas in the Lower Paleozoic Ordovician strata in the Ordos Basin,China is a controversial issue.In the present study,the genesis and distribution characteristics of the Ordovician natural gas were qualitatively investigated based on the composition of the natural gas and the hydrocarbon isotopic composition.Then,the kinetics of the carbon isotope were analyzed to determine the proportions of the gas in the Ordovician gas reservoir contributed from the Carboniferous-Permian and Ordovician strata.The results show the following.Compared to the Upper Paleozoic natural gas,the Ordovician natural gas has a large dryness coefficient.In core areas where gypsum-salt rocks are developed,the gypsum-salt rocks completely isolate the gas sources.The weathering crust of the reservoir in the fifth member of the Majiagou Formation(Ma_(5)^(1+2))originates primarily from the Upper Paleozoic coal-measure source rocks,while the Ma_(5)^(5)and the pre-salt natural gas are mainly derived from the Ordovician source rocks.In the areas where the gypsum-salt rocks are relatively well-developed,the gypsum-salt rocks isolate the gas source to some extent,the pre-salt gas reservoir is mainly derived from the Lower Paleozoic source rocks,and this contribution gradually increases with increasing depth.In the areas where the gypsum-salt rocks are not developed,the proportion of the contribution of the Upper and Lower Paleozoic source rocks to the gas source of the Ordovician gas reservoir is mainly controlled by the volume of gas generated and the other accumulation conditions,and it does not reflect the isolation effect of the gypsum-salt rocks on the gas source.The Ordovician natural gas accumulation models in the central-eastern Ordos Basin can be divided into four types according to the differences in the gas sources.

Influence of sulfate on the generation of bitumen components from kerogen decomposition during catagenesis

High-quality source rocks in saline lacustrine or marine sedimentary environments often show early peak petroleum generation and enhanced hydrocarbon yields,which have conventionally been attributed to organosulfur-enhanced thermal decomposition of kero gen.However,there is increasing awareness that the coexisting inorganic salts,particularly sulfates,might also contribute to the acceleration of petroleum generation.In this study,we investigated the influence of sulfates on the thermal decomposition of kerogen sampled from the Pingliang Formation in the Ordos Basin.Our results demonstrate that the kerogen samples mixed with sulfate generate more hydrocarbons with a lower peak production temperature than their sulfate-free counterparts.Detailed chemical analysis revealed that the presence of sulfates significantly facilitated the generation of resins and asphaltenes at temperatures below 350℃,corresponding in our simulations to the early stage of petroleum generation(Easy%R_o <1.0%).We hypothesize that sulfates can promote the fragmentation of kerogen via direct thermochemical oxidation into a complex mixture of bitumen components that consist mostly of compounds typically encountered in the classical resin and asphaltene fractions.The findings reveal a new reaction paradigm between sulfates and organic macromolecules that could offer useful guidance in the exploration for low-maturity oils.

Development of a large nanocrystalline soft magnetic alloy core with highμ'_(p)Qf products for CSNS-Ⅱ

A waterproof nanocrystalline soft magnetic alloy core with a size of O.D.850 mm×I.D.316 mm×H.25 mm for radio frequency acceleration was successfully developed by winding 18μm 1k107b MA ribbons.Theμ'_(p)Qf products reached 7.5,10,and 12 GHz at 1,3,and 5 MHz,respectively.Theμ'_(p)Qf products of the MA core(O.D.250 mm×I.D.100 mm×H.25 mm)manufactured using a 13μm MA ribbon further increased by 30%.Detailed improvements on the MA core manufacture process are discussed herein.Continuous high-power tests on the new MA cores demonstrated its good performance of waterproofness,particularly its stability of highμ'_(p)Qf products.The MA core with highμ'pQf product and large size can operate under a high average RF power,high electric field,and in deionized water,which will be used in the China Spallation Neutron Source PhaseⅡ(CSNS-Ⅱ).

First branchial cleft cyst accompanied by external auditory canal atresia and middle ear malformation:A case report

BACKGROUND We report a rare case of first branchial cleft anomaly(FBCA)accompanied by bony atresia of the external auditory canal,middle ear malformation,and location malformation of the facial nerve according to the intraoperative findings.CASE SUMMARY A 19-year-old male patient presented to our department with a mass behind the right earlobe and recurrent postauricular swelling and pain since childhood,he also had severe hearing loss in the right ear since birth.The patient underwent surgery including mass removal,mastoidectomy,and simultaneous meatoplasty and ossiculoplasty under microscopy.No facial palsy or recurrence was noted during postoperative follow-up.CONCLUSION FBCAs are rare,and to our knowledge,this is the first report of FBCA accompanied by external auditory canal bony atresia,middle ear malformation,and location malformation of the facial nerve.An effective postauricular approach under microscopy facilitated complete lesion removal and simultaneous otologic reconstruction.

An extremely rare pedunculated lipoma of the hypopharynx: A case report

BACKGROUND Hypopharyngeal lipoma is a rare disease that can lead to asphyxiation after aspiration.Sclerotic lipoma in the hypopharynx is an extremely rare histological type.Hypopharyngeal lipoma should be resected in time after diagnosis.CASE SUMMARY An 86-year-old female patient presented to our department with a long pedunculated mass protruding from her mouth.Until this time,the patient had no dyspnea,dysphagia,or throat discomfort.Physical examination showed stable vital signs and clear consciousness.The pedicel was derived from the posterior wall of the hypopharynx.The tumor was smooth,hyperemic and dark red,about 10 cm long,and 4 cm wide.In order to prevent airway obstruction,the hypopharyngeal tumor was excised in emergent operation.The pharyngeal cavity was exposed by a mouth gag during the operation.A disposable plasma knife was used to completely remove the tumor along the base of the new organism,and no active bleeding occurred.The postoperative pathological results were sclerotic lipoma.CONCLUSION Lipoma in the pharynx is relatively rare.Patients with this condition must be referred immediately to Ear-Nose-Throat specialists and complete surgical excision should be performed as soon as possible to prevent serious complications,such as airway obstruction and death.

Positron emission computed tomography/single photon emission computed tomography in Parkinson disease

Parkinson disease(PD)is the second-most common neurodegenerative disorder.Its main pathological mechanism is the selective degeneration and deletion of dopaminergic neurons in the dense part of the substantia nigra and the damage of dopaminergic neurons caused by the abnormal deposition of a Lewy body,leading to a decreased dopamine level.Positron emission computed tomography(PET)/single photon emission computed tomography(SPECT)is a molecular imaging technology that can directly or indirectly reflect changes in molecular levels by using a specific tracer.With the research and development on the tracers of related enzymes for labeling dopamine transporter and dopamine receptor and for being involved in dopamine formation,this imaging technology has been applied to all aspects of PD research.It not only contributes to clinical work but also provides an important theoretical basis for exploring the pathological mechanism of PD at a molecular level.Therefore,this review discusses the application value of PET/SPECT in PD in terms of early diagnosis,disease severity evaluation,clinical manifestations,differential diagnosis,and pathological mechanism.

Higher harmonic voltage analysis of magnetic-alloy cavity for CSNS/RCS upgrade project

Background A rapid cycling synchrotron(RCS)in China Spallation Neutron Source(CSNS)would be upgraded,and the proton beam power will reach 200-500 kW.Three RF cavities loaded by magnetic-alloy(MA)material will be added in RCS tunnel to form a dual-harmonic RF system with eight ferrite-loaded cavities in RCS.The bandwidth of the MA cavity is wide because of its intrinsic Q value of less than 1.Higher harmonics can be excited in MA cavities,because the RF power is directly fed into the MA cavity from the final stage of the RF power amplifier.The distortion of voltage in the cavity gap caused by higher harmonics may deteriorate the beam quality.The influence of the higher harmonics to beam needs to be evaluated and the amplitude of higher harmonics should to be suppressed.Methods We built a mathematical model with two functions based on the RF bucket acceptance and bunch factor to evalu-ate this influence.Groups of harmful amplitudes and phases of higher harmonics were found according to the mathematical model by using multi-objective particle swarm optimization(MOPSO).Conclusion The dual-harmonic RF system with higher harmonics in CSNS/RCS and a suitable harmonic suppression for MA cavities was discussed according to the results of MOPSO and the beam dynamics simulations.

Design of rapid tuning system for a ferrite-loaded cavity

Introduction A high power,broadband and rapid frequency sweeping RF system was developed to satisfy the demand of China Spallation Neutron Source(CSNS)/Rapid Cycling Synchrotron(RCS).Material and methods The cavity tuning is the key issue which has a great impact on the performance of the whole RF system.To satisfy the requirements of cavity dynamic tuning caused by the nonlinear characteristics of ferrite,some new technologies were developed and applied.Conclusion In this paper,the overall design of the tuning system is introduced.The ensuing discussion focuses on the com-parison between different types of bias supplies,the control algorithm of low-level RF(LLRF)system.The commissioning results with beam power of 100 kW are also shown and discussed.

Treatment of mallet fractures with a transverse two-hole mini plate

To the Editor:Mallet fracture is a very common hand injury.Although non-surgical treatment for some small fragment cases without distal interphalangeal joint(DIPJ)subluxation is acceptable,many authors have considered restoring the joint surface with accurate reduction to be important to prevent secondary osteoarthritis,loss of movement,and poor cosmetic outcomes.[1]To obtain an accurate reduction,several reduction and fixation techniques(such as extension block pinning,hook plate fixation,umbrella handle like K-wire fixation,and so on)have been developed.[2-4] But when the fracture fragment is small or comminuted,stable fixation is quite difficult to achieve based on the current techniques.To develop a more universal method to deal with different types of mallet fractures with fewer complications,a transverse two-hole mini plate was used.