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Thomson scattering is one of the most important diagnostic methods for measuring plasma electron temperature (T e) and electron density (n e). In the diagnostic system, the polychromator is often used to analyze the spectral broadening and intensity of the detected scattered light. The performance of the avalanche photodiode (APD) used in the polychromator is greatly affected by the ambient temperature. The change of ambient temperature will seriously affect the accuracy of Thomson scattering diagnosis. Through experimental analysis, when the ambient temperature increases, the gain of APD will be significantly reduced, resulting in a significant deviation in electron density measurement. Taking the system response at an ambient temperature of 24.1 °C as reference, the deviation of electron density measurement varies from 43% to −16%, with the ambient temperature from 16.6 °C to 29.9 °C. However, the change of ambient temperature has little impact on the measurement of electron temperature. Detailed test of the polychromator shows that the estimated deviation of the electron temperature is within 3%. Due to the change of ambient temperature, the response of the detectors in each channel of the polychromator is inconsistent, which will cause random errors. The influence on electronic temperature calculation is analyzed by numerical simulation. [ABSTRACT FROM AUTHOR]

Summary: Background: Acne vulgaris is widespread across the world. Mapping the latest magnitudes and temporal trends of acne vulgaris provides the essential foundation for targeted public policies at the national, regional and global levels. Objectives: In compliance with the framework of the Global Burden of Disease Study 2019, this study aimed to summarize the incidence, prevalence, DALYs and the corresponding secular trends of acne vulgaris by sex and age group in 204 countries from 1990 to 2019. Methods: The average annual percentage change was calculated to depict the temporal trends in age‐standardized rates (ASRs) of acne vulgaris burden by region, sex and age. Results: Globally, it was estimated that there were 117·4 million [95% uncertainty interval (UI) 103·0–133.7] incident cases of acne vulgaris, 231·2 million (95% UI 208·2–255·5) prevalent cases and 5·0 (95% UI 3·0–7·9) million DALYs, with an increase of approximately 48% compared with 1990. Moreover, the overall ASRs of acne vulgaris increased by approximately 0·55% annually over the past three decades. We observed large disparities in ASRs of acne vulgaris with changing trends in sex, location and age. The ASR of acne vulgaris among women was around 1·3 times that of men, but the sex difference was narrowed because of the pronounced increase among men. The ASRs of acne vulgaris were higher in high‐income regions, but the increasing trend was more pronounced in other regions. Conclusions: The burden rate of acne vulgaris continues to increase in almost all countries. Understanding the specific characteristics of acne vulgaris burden is essential to formulate more effective and targeted interventions for controlling acne burden. Whatis already known about this topic?Acne vulgaris is a common skin condition affecting around 9·4% of the global population.However, there is a sparsity of studies that have taken a truly global, regional and national approach. Whatdoes this study add?Following the Global Burden of Disease Study framework, this study summarizes the global magnitudes of acne vulgaris burden along with the temporal trend.A pronounced acne vulgaris burden rate was observed in Western Europe, high‐income Asia Pacific and East Asia.The burden rate of acne vulgaris continued to increase in almost all countries, except for the USA, Poland, Germany and New Zealand. Linked Comment:L. Naldi. Br J Dermatol 2022; 186:605. Plain language summary available online [ABSTRACT FROM AUTHOR]

• Analyzing the propagation characteristics of non-Gaussian beam. • Designing an in-vacuum collection optics with stable safety shutter structure. • Developing a new compact polychromator suitable for multi-point measurements. A vertical edge Thomson scattering diagnostic system on HL-2 M Tokamak has been developed recently. A Nd: YAG laser (1064 nm, 0.6–2.0 J, 30 Hz, 15 ns) is used as the probe beam. The laser beam propagates vertically through the plasma region and the scattered light is observed horizontally. The combination of a half-wave plate and a polarized beam splitter is used for stray light suppression. A group of in-vacuum collection lens is designed to image the 400 mm scattered region onto the rectangular fiber arrays. The laser beam waist and vertical spatial resolution are 2 mm and 10 mm, respectively. Scattered light is imaged on the 2.20 × 2.86 mm (10 × 13) fiber optic bundle. The development of collection optics with a special designed safety shutter ensures a reliable scattered signal, where the solid angle at central field of view (FOV) is 0.018 sr. A compact polychromator is developed to measure the scattered light. Relative calibration of the filter response (1060 nm, 1052 nm, 1029 nm and 982 nm) and absolute calibration by nitrogen Raman scattering have been completed. In the 2022 plasma campaign of HL-2M, the scattering signal is measured at E 0 = 1.2 J, confirming the capability of the system for pedestal measurement in the future H-mode campaign. [ABSTRACT FROM AUTHOR]