Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.

Trends of HIV Viral Load in Patients under Combined Antiretroviral Treatment in Bangui, Central African Republic

Background: The success of antiretroviral therapy requires better virological monitoring. We described the virological profile of patients on combined antiretroviral therapy (cART) for HIV/AIDS in Bangui, Central African Republic (CAR). Methods: In this prospective cohort study of patients who had been on combined antiretroviral therapy treatment (cART) for at least 12 months in Bangui, only one HIV plasma viral load per patient was realized at the Institut Pasteur of Bangui, between April 4th and November 28th, 2017. Sociodemographic and biological data were collected. Blood samples were taken for viral load. The biocentric generic human immunodeficiency virus (HIV) load test was used to quantify a ribonucleic acid (RNA) HIV-1. Data were analyzed with Stata software version 14. Chi-squared test was used to analyse viral load according to sex and age. The level of significance was set at P ≤ 0.05. Results: A total of 3569 patients were recruited, with a mean age of 40 years (median, 42 years;range, 1 - 84), patients aged 40 - 49 predominating (34.2%). The sex ratio was 0.4. No virus was detectable in plasma from 49.2% of patients, while 42.4% had virological failure (viral load, ≥1000 copies/mL) according to WHO criteria. The risk for virological failure decreased with age (P = 0.001) and was higher among females than males (P = 0.001). Conclusions: The rate of virological failure among patients on cART is very high in the CAR, despite the availability of and access to monitoring of HIV plasma viral load in Bangui. Therefore, adherence to treatment should be evaluated and reinforced in Bangui, CAR.