Experimental results of a magnetic field modification to the radio frequency driver of a negative ion source

A magnetic field produced by a current flowing through the plasma grid(PG) is one of the solutions to reduce the collisional loss of negative ions in a negative ion source, which reduces the electron temperature in front of the PG. However, the magnetic field diffused into the driver has some influence on the plasma outflowing. In order to investigate the effect of changing this magnetic field on the outflowing of plasma from the driver, a circular ring(absorber) of high permeability iron has been introduced at the driver exit, which can reduce the magnetic field around it and improve plasma outflowing. With the application of the absorber, the electron density is increased by about 35%, and the extraction current measured from the extraction grid is increased from 1.02 A to 1.29 A. The results of the extraction experiment with cesium injection show that both the extraction grid(EG) current and H-current are increased when the absorber is introduced.

The application and efficacy of stent place for Budd-Chiari syndrome

Objective To evaluate the application value and efficacy on stent place for Budd-Chiari syndrome(BCS). Methods From January 1990 to May 2017, 2228 patients with BCS were admitted to our institution. The mean age was 43.3 years. Stents were placed in inferior vena cava(IVC), hepatic vein(HV), or both after balloon dilation. During follow-up period, the patency of stent was evaluated by ultrasound regularly and the clinic sign was surveyed by letter, telephone or clinic visit. The restenosis of stent were treated with balloon dilatation and thrombolysis to restore the its function. Results IVC type was diagnosed in 1492 cases, HV type in 510 cases, and mixed type in 226 cases. Eighteen patients aborted treatment because of economic reasons, advanced liver cancer, severe scoliosis, or both bilateral iliac veins and total IVC occlusion. Among the other 2210 cases who underwent endovascular therapy, stents were implanted into IVC in 339 cases, HV in 97 cases, mixed type in 64 cases. The rate of restenosis in IVC stent was 11.50%(39/339). After repeat angioplasty, the long-term patency rate reached to 98.12%. The incidence of HV occlusion caused by IVC stent was 12.09%(n = 41). Restenosis occurred in 47 cases(48.45%) after HV stent placement. However, the 5-year patency rate was 91.75%(89/97) after repeat dilatation and stent re-implantation. The incidence of IVC obstruction caused by HV was 3.33%(3 cases). Conclusion IVC stent placement appears to be an effective treatment for the cases of IVC segmental occlusion, and at the same time, the stent has the dual role of compression and fixation of thrombus and support of lumen. The HV and accessory hepatic vein obstruction could happen when the IVC stent crossed these veins ostium. The incidence of the stent restenosis in the HV was higher than that in the IVC.

Review of Budd-Chiari Syndrome

This study aims to report the Budd-Chiari syndrome clinical research status and progress that has occurred in over nearly 30 years in China, and emphasize the value of imaging in facilitating the diagnosis of Budd-Chiari syndrome based on more than 2500 cases. Findings on ultrasonography, computed tomography, magnetic resonance imaging, and digital subtraction angiography images are used to propose new Budd-Chiari syndrome types and subtypes. The new subtype classification presented here has important value for guiding interventional treatment.This study also proposes a new concept of anatomical and functional obstruction of hepatic vein that stresses the compensatory value of accessory hepatic vein and azygos vein and describes the risk of manipulation of the communication branch of inferior vena cava obstruction in interventional therapy.

First results of negative ion extraction with Cs for CRAFT prototype negative beam source

In order to understand the physics and pre-study the engineering issues for radio frequency(RF)negative beam source,a prototype source with a single driver and three-electrode accelerator was developed.Recently,the beam source was tested on the RF source test facility with RF plasma generation,negative ion production and extraction.A magnetic filter system and a Cs injection system were employed to enhance the negative ion production.As a result,a long pulse of 105 s negative ion beam with current density of 153 A m-2 was repeatedly extracted successfully.The source pressure is 0.6 Pa and the ratio of co-extracted electron and negative ion current is around0.3.The details of design and experimental results of beam source were shown in this letter.

Achievement of 1000 s plasma generation of RF source for neutral beam injector

A radio frequency(RF) ion source was developed for neutral beam injector in Institute of Plasma Physics, Chinese Academy of Sciences(ASIPP). A cylindrical driver based RF plasma source was tested and optimized for long pulse operation. Recently, the plasma source achieved 1000 s stable plasma discharge with RF power of 35 k W and source pressure of 0.7 Pa for the first time.The heat loading on each of driver components such as the Faraday shield(FS), RF coil and expansion chamber was measured by the water flow calorimeter system. The experiment results showed that FS is the component with highest heat loading and the heat loading on FS was about 65.8% of total heat loading on source. The details of the long pulse operation of RF plasma source are presented in this paper.

Machine learning assisted prediction of charge transfer properties in organic solar cells by using morphology-related descriptors

Charge transfer and transport properties are crucial in the photophysical process of exciton dissociation and recombination at the donor/acceptor(D/A)interface.Herein,machine learning(ML)is applied to predict the charge transfer state energy(ECT)and identify the relationship between ECT and intermolecular packing structures sampled from molecular dynamics(MD)simulations on fullerene-and non-fullerene-based systems with different D/A ratios(RDA),oligomer sizes,and D/A pairs.The gradient boosting regression(GBR)exhibits satisfactory performance(r=0.96)in predicting ECT withπ-packing related features,aggregation extent,backbone of donor,and energy levels of frontier molecular orbitals.The charge transport property affected byπ-packing with different RDA has also been investigated by space-charge-limited current(SCLC)measurement and MD simulations.The SCLC results indicate an improved hole transport of non-fullerene system PM6/Y6 with RDA of 1.2:1 in comparison with the 1:1 counterpart,which is mainly attributed to the bridge role of donor unit in Y6.The reduced energetic disorder is correlated with the improved miscibility of polymer with RDA increased from 1:1 to 1.2:1.The morphology-related features are also applicable to other complicated systems,such as perovskite solar cells,to bridge the gap between device performance and microscopic packing structures.