A high-power long lifetime beam dump for the Thomson scattering diagnostic system in the XuanLong-50 experiment.

The Energy iNNovation's XuanLong-50 is a spherical torus experiment with up to 10 s plasma operation duration. A 3 J/50 Hz pulsed laser is used in the Thomson scattering diagnostic system that is developed to measure the time evolutions of plasma electron temperature and density profiles. The expected laser pulse number is about 7.5 × 106/year with a power load of 150 W. To meet at least 1-year lifetime requirement, a Chevron type beam dump with polished molybdenum plates is designed and fabricated, which absorbs the laser beam energy in a 3D structure to reduce the laser fluence deposited on the material surface. To prevent the backscattered stray light from interfering with the Thomson scattering measurements, a 7.5 m beam path with folding mirrors is set between the beam dump and the plasma scattering volumes. Details of the beam dump design procedure including the laser beam profile control, multi-pulse laser damage threshold, heat dissipation, Zemax modeling, folding mirror selection, and beam path enclosure are presented together with the testing results.

A novel polychromator calibration method for Thomson scattering diagnostics.

Polychromators are most frequently used in Thomson scattering (TS) diagnostics to analyze the scattered light spectrum and intensity so that the plasma electron temperature (Te) and density (ne) can be derived. For Te measurements, the spectral response of the polychromator channels and the relative spectral responsivities need to be calibrated. The spectral response is calibrated with a bromine tungsten lamp and a monochromator in a conventional way. A novel method for calibrating the relative spectral responsivities of the polychromators is described in detail. A broadband pulsed Light Emission Diode (LED) is used, which has a spectral irradiance similar to that of the TS spectrum, and the LED can be driven in pulse mode with the pulse width similar to the TS signal pulse width of about 10-20 ns full width at half maximum. This new method allows for the calibration to be done after the polychromator is fully installed, and in situ system calibration can be easily performed, showing the advantages of accuracy, simplicity, efficiency, and flexibility. For ne measurements, absolute sensitivity calibration is done by Rayleigh scattering with argon gas. Formulas for calculating the plasma density from the calibration data and the polychromator signals from the off-laser wavelength channels are presented.

Thomson scattering diagnostic system for the XuanLong-50 experiment.

A 15-point Thomson scattering diagnostic system is developed for ENN's spherical torus experiment XuanLong-50 (EXL-50). A BeamTech laser with 3 J/pulse (1064 nm wavelength) at 50 Hz repetition rate is chosen for measurements during EXL-50 plasma operations. To enable measurements at low density (∼0.5 × 1018 m-3) plasma operations, the opto-mechanical subsystems are carefully designed to maximize the collection and transmission of the scattered light and to minimize the stray light level. In addition, the high bandwidth trans-impedance amplifiers and segmented high speed waveform digitizers allow for the application of muti-pulse averaging to further improve the signal-to-noise ratio. Details of the diagnostic system are described and initial experimental results are presented.

Time resolved absolute extreme ultraviolet radiation measurement on the ENN XuanLong-50 spherical tokamak.

A plasma radiation measurement system for a wide spectral range, based on compact Absolute eXtreme UltraViolet (AXUV) silicon photodiodes, has been implemented on the newly constructed ENN XuanLong-50 (EXL-50) spherical tokamak. The system consists of two 16-channel AXUV16ELG arrays and one AXUV63HS1 single-cell detector mounted on ceramic sockets. The two arrays, facing toward the EXL-50 slim central post from two locations inside a top and a side ConFlat 400 port, have 32 view chords covering the interested plasma region in a poloidal cross section at toroidal 330°. The single-cell detector, seated on a retractable feedthrough, could be arranged flexibly with the help of an ultra-high vacuum compatible gate valve. The design details together with considerations on the EXL-50 specific engineering realities and physics requirements are described. Preliminary results from the EXL-50 2020 experimental campaign are presented.

Toroidal soft x-ray array on the EXL-50 spherical tokamak.

A toroidal soft x-ray array system for spectrum and intensity measurements on the EXL-50 spherical tokamak is described. Silicon drift detectors and digital multichannel analyzers are adopted for all 21 channels of the array, and an average energy resolution of 147 eV at 5.89 keV has been achieved at count rates over 500 kcps. In total, 20 channels of the array are symmetrically observed in both co- and counter-current directions on the EXL-50 mid-plane with a spatial resolution of around 10 cm, and the remaining one serves as a background reference channel. Tungsten emissions from tungsten coating of the limiters on the central post are observed. The influence of hard x rays on measured soft x-ray spectra and system operation is discussed.

Tangential hard x-ray diagnostic array on the EXL-50 spherical tokamak.

A tangential hard x-ray (HXR) diagnostic on the newly constructed ENN XuanLong-50 (EXL-50) spherical tokamak for fast electron emission studies is presented. The HXR detection system consists of a symmetrical CdZnTe semiconductor detector array with a spectral sensitivity range of 20-300 keV. 25 channels have been designed on the 270° horizontal vacuum port with 12 sight lines to observe the forward emission, 12 sight lines to observe the backward emission of fast electrons, and 1 for viewing the central. Currently, ten channels have been in operation in the EXL-50 experiments. The systems are designed to measure the x-ray spectra for the estimation of fast electron temperature and electron velocity distribution in the EXL-50 experiment, which will be useful for understanding the dynamics of fast electrons generated by electron cyclotron resonance heating, for plasma instability and transport studies and for the analysis of plasma heating efficiency.

[Effect of interpregnancy interval of childbearing aged women on birth weight of single live birth neonates].

Objective: To understand the effect of interpregnancy interval (IPI) of childbearing aged women on the birth weight of single live birth neonates in Shaanxi province. Methods: A questionnaire survey was conducted among the childbearing aged women selected through multistage stratified random sampling in Shaanxi during 20l0-2013, all the childbearing aged women had definite pregnancy outcomes. The interpregnancy interval of the childbearing aged women and the birth weight of the newborns were used as the independent variables and dependent variables respectively in multiple linear regression model and quantile regression model, and confounding factors were controlled. Results: A total of 13 063 women at childbearing age and their infants were investigated. The incidence of low birth weight and macrosomia was 3.54% and 7.62% respectively. Multiple linear regression analysis showed that there was no significant difference in birth weight among different IPI group and control group. Quantile regression analysis showed when birth weight was at 5 percentiles, the difference in birth weight between newborns whose mothers had short interpregnancy interval (<12 months) and those in control group was significant, when the birth weight was ≥90 percentiles, the birth weights of newborns whose mothers had long interpregnancy interval (60-119 months) were higher than those in control group, the difference was significant. As the increase of the percentiles of birth weight, the extent of changes gradually increased. Conclusion: The analysis indicated that both short (<12 months) and long (60-119 months) interpregnancy interval would had negative effects on birth weights of newborns. Therefore, planning for pregnancy is important for having a good perinatal outcome.

[Temperature that modifies the effect of air pollution on emergency room visits for circulatory and respiratory diseases in Beijing, China].

Objective: To analyze the temperature modification effect on emergency room visits for circulatory and respiratory diseases caused by air pollution, in Beijing. Methods: Data on both circulatory and respiratory diseases in 2010 and 2011 were collected, Both meteorological and air pollutants related data were obtained from the National Scientific Data Sharing Platform for Population and Health. By using the stratified time-series models, we analyzed the effects of air pollution on emergency room visits for circulatory and respiratory diseases under different temperature zones, from 2010 to 2011, in Beijing. Results: Low temperature (daily average temperature<-4.9 ℃) seemed to have obviously enhanced the effect of air pollution index (API) on emergency room visits for circulatory diseases, Under 10 units of API, the relative risks and confidence interval appeared as 1.067 (1.054-1.080). However, high (daily average temperature between 24.4 ℃ and 28.5 ℃) and extra-high temperature (daily average temperature >28.5 ℃) could enhance the effect of API on emergency room visits for respiratory diseases, Under 10 units of API, the relative risks and confidence interval were 1.021 (1.015-1.028) and 1.006 (1.003-1.008), respectively. Conclusion: Temperature seemed to have modified the association between air pollution and both circulatory and respiratory diseases.

[Epidemiological study on adverse pregnancy outcomes in Shaanxi province].

Objective: To understand the incidence and epidemiological characteristics of adverse pregnancy outcome in Shaanxi province. Methods: General information of the study was derived from the prevalence and risk factors of birth defects in Shaanxi province in 2010-2013. Descriptive epidemiological method was used to analyze the data of adverse pregnancy outcome. Results: The overall incidence of adverse pregnancy outcome was 25.45% during 2010-2013 (26.84% in 2010, 26.11% in 2011, 24.96% in 2012 and 24.80% in 2013, respectively). Fetal macrosomia and low birth weight accounted for 31.91% and 23.42%, spontaneous abortion and premature delivery accounted for 18.94% and 16.65%, while birth defects and embryo death in the palace accounted for 7.38% and 1.70%, respectively. There were significant differences in distribution of adverse pregnancy outcome among different age groups (P<0.001) and different years (P<0.05). Age was positively associated with risk on adverse pregnancy outcomes (P<0.001). The incidence of adverse pregnancy outcome were high in Liquan (37.49%), Wugong (35.50%) and Qianxian counties (35.13%). Conclusions: The overall incidence of adverse pregnancy outcome was 25.45% in Shaanxi. Fetal macrosomia, low birth weight and spontaneous abortion were the three major types of adverse pregnancy outcome, while age and area were related factors. Targeted strategies should be taken to reduce the incidence of adverse pregnancy outcome in Shaanxi.

[Incidence of fetal macrosomia among single live birth neonates and influencing factors in Xi' an, 2010-2013].

OBJECTIVE: To analyze the incidence and influencing factors on fetal macrosomia among single live birth neonates in Xi' an. METHODS: A questionnaire survey was conducted among women at the childbearing age who were selected through multi stage stratified random sampling in Xi 'an during 2010-2013. All the childbearing aged women involved, were in pregnancy or having definite pregnancy outcomes. RESULTS: A total of 4 970 women at childbearing age and their infants were investigated. The overall incidence of fetal macrosomia weight among the single live birth neonates under study, was 9.7% during 2010-2013 (8.9% in 2010, 8.1% in 2011, 10.0% in 2012 and 10.1% in 2013, respectively). The incidence rates of fetal macrosomia appeared 10.5% in the central district and, 8.6% in the rural-urban area of Xi'an. There were statistically significant differences (P<0.05) seen between the two areas. RESULTS of logistic regression analysis suggested that factors as: having male newborn (OR=1.717, 95%CI: 1.402-2.102), drinking during pregnancy (OR=2.174, 95%CI: 1.042-4.533), gestational diabetes (OR=1.680, 95%CI: 1.100-2.568) gestational age≥42 (compared with 37-41, OR=2.565, 95% CI: 1.306-5.039), being multipara (OR=1.874, 95% CI: 1.492-2.354) were risk factors for the fetal macrosomia. CONCLUSION: The incidence of fetal macrosomia in Xi' an was higher than the national figures. The incidence of fetal macrosomia was higher in the central district than in rural-urban area. Having male neonate, postmature birth, gestational diabetes, being multipara, drinking during pregnancy were the risk factors related to fetal macrosomia.

[Effect of folic acid supplementation in childbearing aged women during pregnancy on neonate birth weight in Shaanxi province].

OBJECTIVE: To investigate the effect of folic acid supplementation in childbearing aged women during pregnancy on the birth weight of newborns in Shaanxi province. METHODS: A questionnaire survey was conducted among the childbearing aged women selected through multistage stratified random sampling in Shaanxi during 2010-2013, all of these childbearing aged women were in pregnancy or had definite pregnancy outcomes. The birth weight of newborns and folic acid supplementation during pregnancy were used as the dependent variables and independent variables respectively in multiple linear regression model and quantile regression model and confounding factors were controlled. RESULTS: Multiple linear regression analysis showed that the birth weight of newborns whose mothers had folic acid supplementation during pregnancy were significantly higher than those whose mothers had no folic acid supplementation during pregnancy, an average increase of 29.56 g(B=29.56, t=4.69 and P<0.01). Quantile regression analysis showed from very low to higher percentiles(q=0-0.55, q=0.65, q=0.75-0.80), the birth weights of newborns whose mothers supplemented folic acid were higher than those whose mother did not supplement folic acid, the difference was significant, but the increase varied. As the increase of the percentiles of birth weight, the body weight increase declined gradually in those whose mothers had folic acid supplementation compared with those whose mothers had no folic acid supplementation. CONCLUSION: Folic acid supplementation during pregnancy can increase the birth weight of newborns, the influence was greater in newborns with lower body weight than in newborns with higher body weight.

[Effect of air pollution on pregnancy outcome of women at reproductive age in Xi'an, 2010-2013].

Objective: To compare the differences in the incidence of adverse pregnancy outcome in different area, and confirm if the incidence of adverse pregnancy outcomes is closely associated with air pollution. Methods: A cross-sectional study was conducted in the central urban area and the rural-urban area of Xi'an through a questionnaire survey conducted among the local reproductive women selected through multistage stratified random sampling during 2010-2013, all the reproductive women surveyed were in pregnancy or had definite pregnancy outcomes. Results: The annual average of SO2 concentration in the central urban area was 38-54 µg/m3, higher than that in the rural-urban area (29-43 µg/m3). The annual average NO2 concentration in the central urban area was 29-87 µg/m3, higher than that in the rural-urban area (22-42 µg/m3). The incidence of birth defects was higher in the central urban area than in the rural-urban area (2.1% vs. 1.0%), the difference was significant (P<0.05). After adjusting for confounding factors, logistic regression analysis showed the incidence of birth defects in the central urban area was still significantly higher than that in the rural-urban area, the difference was significant (P<0.05). Conclusion: The incidence of adverse pregnancy was closely associated with the level of air pollution.