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.

An analysis and preliminary experiment of the discharge characteristics of RF ion source with electromagnetic shielding

Combined with two-dimensional(2D)and three-dimensional(3D)finite element analysis and preliminary experimental tests,the effects of size and placement of the electromagnetic shield of the radio-frequency(RF)ion source with two drivers on plasma parameters and RF power transfer efficiency are analyzed.It is found that the same input direction of the current is better for the RF ion source with multiple drivers.The electromagnetic shield(EMS)should be placed symmetrically around the drivers,which is beneficial for the plasma to distribute uniformly and symmetrically in both drivers.Furthermore,the bigger the EMS shield radius is the better generating a higher electron density.These results will be of guiding significance to the design of electromagnetic shielding for RF ion sources with a multi-driver.

Redo inferior pubectomy for failed anastomotic urethroplasty in pelvic fracture urethral injury

Objectives:To assess the effect of redo inferior pubectomy on the management of complicated pelvic fracture urethral injury(PFUI)in patients with a history of failed anastomotic urethroplasty.Materials and methods:We retrospectively reviewed all patients receiving redo anastomotic urethroplasty with redo inferior pubectomy for failed PFUI between January 2010 and December 2021.Patients with incomplete data and those who were lost to follow-up were excluded.Successful urethroplasty was defined as the restoration of a uniform urethral caliber without stenosis or leakage and further intervention.Functional results,including erectile function and urinary continence,were evaluated.Descriptive statistical analyses were then performed.Results:Thirty-one patients were included in this study.Among them,concomitant urethrorectal fistula occurred in 2 patients,and concomitant enlarged bladder neck occurred in 1.The stenosis site was the bulbomembranous urethra in 2 patients and the prostatomembranous urethra in 29.The mean length of urethral stenosis in all patients was 3.1 cm(range,2.0-5.0 cm).After a mean follow-up of 34.6 months,the final success rate was 96.8%.The incidence of erectile dysfunction reached 77.4%(24/31).Normal continence was achieved in 27(87.1%)patients.One patient developed urinary incontinence of gradeⅡrequiring urinary pads because of an enlarged bladder neck.According to the Clavien-Dindo classification,postoperative complications of grade I occurred in 7 patients and gradeⅡin 4.Conclusions:Repeat anastomotic urethroplasty with repeat inferior pubectomy provides reliable success rates for failed PFUI.In complicated cases,it should be known and mastered.