Dicyandiamide Sorption-Desorption Behavior on Soils and Peat Humus

The sorption-desorption behavior of dicyandiamide (DCD) is an importantchemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCDsorption-desorption on a phaeozem (Mollisol), a burozem (Alfisol), a soil with organicmatter-removed and peat humus using the batch-equilibration procedure, and identified soilproperties that influenced DCD sorption. The sorption on peat humus was higher than that on thephaeozem and the burozem, with much lower sorption observed on the soil with organic matter-removed,indicating that soil organic matter was the main carrier of DCD sorption. Due to its amphipathicproperty the DCD molecule sorption on the phaeozem and the burozem decreased as pH increased fromabout 2 to 5, but a further increase in pH led to a rise in DCD sorption. The DCD desorptionhysteretic effect for peat humus was greater than that for the phaeozem and the burozem using 0.01mol L^(-1) CaCl_2 as the background electrolyte, suggesting that the hydrophobic domains of organicmatter may play an important role in DCD sorption.

Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils

Effects of free iron oxyhydrates （Fed） and soil organic matter （SOM） on copper （Cu^2＋） sorption-desorption behavior by size fractions of aggregates from two typical paddy soils （Ferric-Accumulic Stagnic Anthrosol （Soil H） and Gleyic Stagnic Anthrosol （Soil W）） were investigated with and without treatments of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1：20, 25℃. For Soil H, Cu^2＋ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bnlk sample. However, Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu^2＋ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu^2＋ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction （only 9.5%） for Soil H. While removal of SOM with H2O2 tendend to increase the desorption rate, DCB- and H2O2-treatments caused decrease in Cu^2＋ retention capacity of size fractions, Particularly, there hardly remained Cu^2＋ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized status among the size fractions. Thus, enrichment and turnover of SOM in paddy soils may have great effects on metal retention and chemical mobility in paddy soils.

Phosphate Sorption-Desorption Characteristics in Two Inceptisols and an Alfisol of Chattisgarh, India

Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradientsin physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties. Fromthe P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were alsofitted both to the Langmuir and Freundlich Equations. The mean sorption maximum values for three different soil serieswere: Bastar > Geedam > Mosodi. The fraction of added phosphate sorbed for the 3 series followed this same trend asdid SPR; the phosphate sorption maximum and the maximum phosphate buffering capacity, which were estimated by theLangmuir isotherm; and the Freundlich constant 1/n. However, phosphate desorption, as well as the maximum recoverypercent did not follow this order. The phosphate affinity constant (K) was also different following the same progressionfor the 3 soil series as the Freundlich constant K’, which measured sorption strength. Meanwhile, an inverse order existedfor K and K’ versus the percent desorbed relative to the sorbed as well as the maximum recovery percent. In addition,significant correlation coefficients among sorption parameters of P and soil factors were found.

Phosphorus Sorption-desorption Characteristics of Ditch Sediments from Different Land Uses in a Small Headwater Catchment in the Central Sichuan Basin of China

Investigation of phosphorus (P) sorption-desorption characteristics of drainage ditch sediments is important for better understanding on sediment P transport behaviors in ditches. Surface ditch sediment samples were collected from headwater sub-catchment of forestland, sloping cropland, paddy field, and residential area in a representative catchment in the central Sichuan Basin. These sediment samples were used for determination of P sorption-desorption characteristics by a batch equilibrium technique. Results showed that the maximum P sorption capacities (Qm) in the sediments ranged from 159.7 to 263.7 mg/kg, while higher Qm were observed in the ditch sediments from the paddy fields. The Qm was significantly and positively correlated with oxalate-extractable Fe and Al oxides (r=0.97 and 0.98, p < 0.01), clay fraction (r = 0.78, p < 0.05) and organic matter (r = 0.95, p < 0.01). Sediment pH, clay and organic matter influenced the P sorption through amorphous Fe and Al oxides. CaCO3 content was negatively correlated with the Qm (r = -0.83, p < 0.05), implying that saturated CaCO3 (> 50 g/kg) would not increase P sorption capacity in the ditch sediments. The ditch sediments featured a linear desorption curve, suggesting that P release risk would be enhanced with the increase of the P adsorption. The P desorption rate was positively correlated with Olsen P (r = 0.94, p < 0.01), but negatively related to the fine particle-size fractions (r = -0.92, p < 0.01), the sum of the amorphous Fe and Al oxides (r = -0.67, p < 0.05) and the P sorption capacity (r = -0.59, p < 0.05). The ditch sediments from residential area had a higher P release risk than that from the other ditches of forestland, sloping cropland and paddy field. The P sorption index (PSI) derived from single-point measurement was significantly correlated with the P sorption capacity (r = 0.99, p < 0.01), and could be used for estimating Qm as 1.64 times PSI plus 24.0 (Qm = 1.64 PSI + 24.0) for similar sediments with highly calcareous soils and sediments. Ditch cleaning and sediment removal for the ditch in residential area were recommended in this area to reduce the P release risk.

Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance.In this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation doses.The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)irradiation.Significant J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film devices.Clear Shapiro steps are observed under 10 GHz microwave irradiation.The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

Evolution of helium bubbles in FeCoNiCr-based high-entropy alloys containing γ′ nanoprecipitates

A series of high-entropy alloys(HEAs) containing nanoprecipitates of varying sizes is successfully prepared by a non-consuming vacuum arc melting method.In order to study the irradiation evolution of helium bubbles in the FeCoNiCrbased HE As with γ' precipitates,these samples are irradiated by 100-keV helium ions with a fluence of 5 × 10^(20) ions/m^(2) at 293 K and 673 K,respectively.And the samples irradiated at room temperature are annealed at different temperatures to examine the diffusion behavior of helium bubbles.Transmission electron microscope(TEM) is employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles.Experimental results reveal that nanosized,spherical,dispersed,coherent,and ordered L1_(2)-type Ni_(3)Ti γ' precipitations are introduced into FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs by means of ageing treatments at temperatures between 1073 K and 1123 K.Under the ageing treatment conditions adopted in this work,γ' nanoparticles are precipitated in FeCoNiCr(Ni_(3)Ti)_(0.1) HE As,with average diameters of 15.80 nm,37.09 nm,and 62.50 nm,respectively.The average sizes of helium bubbles observed in samples after 673-K irradiation are 1.46 nm,1.65 nm,and 1.58 nm,respectively.The improvement in the irradiation resistance of FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs is evidenced by the diminution in bubbles size.Furthermore,the FeCoNiCr(Ni_(3)Ti)_(0.1) HEAs containing γ' precipitates of 15.8 nm exhibits the minimum size and density of helium bubbles,which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries.Subsequently,annealing experiments conducted after 293-K irradiation indicate that HEAs containing precipitated phases exhibits smaller apparent activation energy(E_(a)) for helium bubbles,resulting in larger helium bubble size.This study provides guidance for improving the irradiation resistance of L1_(2)-strengthened high-entropy alloy.

Genetic source,migration and accumulation of helium under deep thermal fluid activities:A case study of Ledong diapir area in Yinggehai Basin,South China Sea

Based on the geochemical parameters and analytical data,the heat conservation equation,mass balance law,Rayleigh fractionation model and other methods were used to quantify the in-situ yield and external flux of crust-derived helium,and the initial He concentration and thermal driving mechanism of mantle-derived helium,in the Ledong Diapir area,the Yinggehai Basin,in order to understand the genetic source,migration and accumulation mechanisms of helium under deep thermal fluid activities.The average content of mantle-derived He is only 0.0014%,the ^(3)He/^(4)He value is(0.002–2.190)×10^(−6),and the R/Ra value ranges from 0.01 to 1.52,indicating the contribution of mantle-derived He is 0.09%–19.84%,while the proportion of crust-derived helium can reach over 80%.Quantitative analysis indicates that the crust-derived helium is dominated by external input,followed by in-situ production,in the Ledong diapir area.The crust-derived helium exhibits an in-situ 4 He yield rate of(7.66–7.95)×10^(−13)cm^(3)/(a·g),an in-situ 4 He yield of(4.10–4.25)×10^(−4)cm^(3)/g,and an external 4 He influx of(5.84–9.06)×10^(−2)cm^(3)/g.These results may be related to atmospheric recharge into formation fluid and deep rock-water interactions.The ratio of initial mole volume of 3 He to enthalpy(W)is(0.004–0.018)×10^(−11) cm^(3)/J,and the heat contribution from the deep mantle(X_(M))accounts for 7.63%–36.18%,indicating that deep hot fluid activities drive the migration of mantle-derived 3 He.The primary helium migration depends on advection,while the secondary migration is controlled by hydrothermal degassing and gas-liquid separation.From deep to shallow layers,the CO_(2/3) He value rises from 1.34×10^(9)to 486×10^(9),indicating large amount of CO_(2)has escaped.Under the influence of deep thermal fluid,helium migration and accumulation mechanisms include:deep heat driven diffusion,advection release,vertical hydrothermal degassing,shallow lateral migration,accumulation in traps far from faults,partial pressure balance and sealing capability.

Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron

The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods.The results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile GBs.The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation mechanism.However,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at fractures.For bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation angle.Interestingly,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

Characteristics and main controlling factors of helium resources in the main petroliferous basins of the North China Craton

At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that's why their methane resource characteristics are essentially the same. The calculated ~4He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ~4He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins;there is almost no contribution of the mantle-derived CH_4, which suggests that the transport and uplift of mantle-derived ~3He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ~3He mixing in the basins. Combined with the results of regional volcanic and geophysical studies,it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ~3He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ~3He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

Global helium(He) shortage is a challenging problem;however, the types of helium source rock and the mechanisms of He generation and release therein remain still poorly understood. In this study, in order to evaluate the potential of granite as an effective helium source rock, we collected granitic samples from the North Qinling Orogen, Central China, in the south of the helium-rich Weihe Basin. The helium generation and release behaviors in granite were studied through analysis of U and Th concentrations, EMPA images, and He and Ar concentrations and isotopic ratios extracted by crushing and stepwise heating. The results indicate that Ar has a better retention and a lower mobility than He. 3 He/4 He ratios released by crushing and stepwise heating are 0.016–0.056 RA and 0.003–0.572 RA, respectively, where RA is the atmospheric 3 He/4 He of 1.4×10-6, reflecting a crustal and radiogenic source. Helium concentrations extracted by the two ways are 0.13–0.95 ucm3 STP/g and 7.82–115.62 ucm3 STP/g, respectively, suggesting that matrix-sited He accounts for more than 98% of total helium preserved in granite. In addition, the total generated He amounts in granites are calculated based on the measured U and Th concentrations in granitic samples. Dividing the preserved He quantities by the generated He amounts, it turned out that less than 10% of He produced since the formation of the granite is preserved in the rock over geological time, suggesting that more than 90% generated He can be transferred to the Weihe Basin. Temperature and fracture are the two critical factors controlling He release. Based on the relationship between He diffusivity of granites and temperature and the He closure temperatures of a variety of U-and Th-rich minerals(27–250°C), we estimate that He can be partially released out of granite at the depths <400 m and totally released at the depths >7800 m. Fractures provide effective transfer of free He from deep source rocks to shallow reservoirs. Finally, a model on granite as an effective helium source rock is established. We suggest exploring He resources in hydrocarbon basins with granitic basement(or adjacent to granite bodies), high geothermal field, and young active fractures.

Helium Isotope Geochemistry of Ultrahigh-Pressure Metamorphic Eclogites From the Dabie-Sulu Terrane in East China

: The 3He/4He ratios of most eclogites from the Dabie-Sulu terrane range from 0.056 to 0.67 Ra; the data points fall into the mixing part of the crust and the mantle in the 3He-4He diagram. The 3He/4He ratios of eclogites are obviously correlated with the types of their surrounding rocks. The helium isotope composition of the eclogites from the Bixiling complex possesses characters of mantle-derived rocks with the 3He/4He ratio being 5.6 Ra. The 4He concentration of the eclogites exhibits visible inverse correlation with the δ18O value of the quartz in the eclogites from the Sulu area. The δ18O values of the eclogites change synchronously with those of the country rocks. Those results suggest that protoliths of the eclogites were basic-ultrabasic rock bodies or veins intruding into the continental crust in the early stage; strong exchange and hybridization between the basic-ultrabasic rocks and continental rocks and the atmospheric water during the intrusion led to abrupt increase of the 3He/4He ratios, δ18O values and Nd(0) values of the intrusive bodies or veins, which show characters of continental rocks. This indicates that the eclogites are autochthonous.

Degassing of primordial hydrogen and helium as the major energy source for internal terrestrial processes

Examples of the mightiest energy releases by great earthquakes and volcanic eruptions and hypotheses providing explanations for them are analyzed along with the results of some recently pub- lished researches and visualizations. The emerging conclusions are that the mechanism of the strong earthquake is a chemical explosion; that volcanic eruption is a special type of earthquake wherein the hypocenter rises to the earth-surface; and that there is an association between the seismic-volcanic processes and mantle ＂fluids＂ and the lack of energy for mantle plumes. A conceptual system of hypoth- eses is put forward to explain the conservation of energy during Earth＇s accretion, its quasi-stable release by primordial H- and He-degassing and of the crucial role of the energy of degassing-eomprising- reactions in endogenic processes. Specific mechanisms and chemical processes are proposed for the gas-liquid mantle plumes melting through the solid mantle using heat-energy released in reactions of their metamorphic and chemical transformation under gradual decrease of pressure and temperature; volcanic gases are put forward as energy carriers. 3He performance as a unique measuring transformer correlative to the internal heat flow was used for calculation of energy release by degassing; it equals to 5.12 × 1020 J/yr, an amount of energy five-fold greater than the entire energy loss involved in earthquake and volcanic activity. The hypotheses proposed are objectively testable.

Crustal Composition of China Continent Constrained from Heat Flow Data and Helium Isotope Ratio of Underground Fluid

Based on conservation of energy principle and heat flow data in China continent, the upper limit of 1.3 μW/m3 heat production is obtained for continental crust in China. Furthermore, using the data of heat flow and helium isotope ratio of underground fluid, the heat productions of different tectonic units in China continent are estimated in range of 0.58-1.12 μW/m3 with a median of 0.85 μW/m3. Accordingly, the contents of U, Th and K20 in China crust are in ranges of 0.83-1.76 μg/g, 3.16-6.69 μg/g, and 1.0%-2.12%, respectively. These results indicate that the abundance of radioactive elements in the crust of China continent is much higher than that of Archean crust; and this fact implies China＇s continental crust is much evolved in chemical composition. Meanwhile, significant lateral variation of crustal composition is also exhibited among different tectonic units in China continent. The crust of eastern China is much enriched in incompatible elements such as U, Th and K than that of western China; and the crust of orogenic belts is more enriched than that of platform regions. It can also be inferred that the crusts of eastern China and orogenic belts are much felsic than those of western China and platform regions, respectively, derived from the positive correlation between the heat production and SiO2 content of bulk crust. This deduction is consistent with the results derived from the crustal seismic velocity data in China. According to the facts of the lower seismic velocity of China than the average value of global crust, and the higher heat production of China continent compared with global crust composition models published by previous studies, it is deduced that the average composition models of global continent crust by Rudnick and Fountain （1995）, Rudnick and Gao （2003）, Weaver and Tarney （1984）, Shaw et al. （1986）, and Wedepohl （1995） overestimate the abundance of incompatible elements such as U, Th and K of continental crust.

Helium Retention and Desorption Behaviour of Reduced Activation Ferritic/Martenstic Steel

The reduced activation ferritic/martenstic steel CLF-1 prepared by the Southwestern Institute of Physics in China was irradiated by helium ions with an energy of 5 keV at room temperature using an electron cyclotron resonance （ECR） ion irradiation apparatus. After the irradiation, the helium retention and desorption were investigated using a technique of thermal desorption spectroscopy （TDS）. The experiment was conducted with both the normal and welded samples. Blisters were observed after the helium ion irradiation, and the surface density of blisters in the welded samples was lower than that in the non-welded samples. Three desorption peaks were observed in both the non-welded and welded samples. These desorption peaks corresponded to those of blister ruptures and the helium release from the inner bubbles and the defects. The amount of helium retained in the welded samples was approximately the same as that in the non- welded samples, which was much less than other reduced activation materials, such as vanadium alloy and SiC/SiC composites.

Helium Droplets： An Apparatus to Study Ultra Cold Chemistry

A new pulsed helium nano droplets machine has been constructed. The droplets were gener- ated by expansion of the pure helium through the cryogenic valve attached to a closed-cycle cryostat. The mean size of helium droplets can be controlled between 103 and 105 helium atoms by tuning the backing pressure （10-40 bar） and temperature （10-30 K）. Compared with the continuous-flow beam source, the density of droplet is at least one order of magni- tude higher, which offers the opportunity to combine the system with the commercial pulsed laser to study chemical reactions inside of the superfluid helium at ultra-low temperature. The performance for the system has been checked by studying the photodissociation of CH3I doped droplets at 252 nm with the velocity map imaging technique. The photofragments, CH3, were detected by （2＋1） resonance enhanced multiphoton ionization. The speed and angular distributions derived from resulting images show clear evidence of the relaxation effect by the surrounding helium atoms. The pulsed helium droplets depletion spectroscopy was also demonstrated. The depletion spectrum of benzene doped helium droplets indicates that less than 3% depletion can be observed with the newly constructed apparatus.

Process Modeling and Dynamic Simulation for EAST Helium Refrigerator

In this paper,the process modeling and dynamic simulation for the EAST helium refrigerator has been completed.The cryogenic process model is described and the main components are customized in detail.The process model is controlled by the PLC simulator,and the realtime communication between the process model and the controllers is achieved by a customized interface.Validation of the process model has been confirmed based on EAST experimental data during the cool down process of 300-80 K.Simulation results indicate that this process simulator is able to reproduce dynamic behaviors of the EAST helium refrigerator very well for the operation of long pulsed plasma discharge.The cryogenic process simulator based on control architecture is available for operation optimization and control design of EAST cryogenic systems to cope with the long pulsed heat loads in the future.

Process Modeling and Control Simulation for a 500W@4.5K Helium Refrigerator

In order to investigate dynamic behaviors of a 500W@ 4.5K helium refrigerator,the process simulator has been completed. The cryogenic process model is described and main components are customized. The realtime communication between the process model and the control system has been achieved. Compared with the preliminary experimental data,the errors of temperatures during the process of 300 K-80 K are less than 10%.The process model is validated to predict the cool-down process very well. The controller parameters are tuned in simulation and applied to the actual refrigerator suitably. Based on the dynamic simulation,the operation of Joule-Thomson( JT) by pass valve has been optimized. And the cool- down process from 300 K to 4. 5 K has been simulated under the control programs. Simulation results indicate that this dynamic simulator based on actual control architecture is available to process control and operation optimization for the helium refrigerators.

ADS Injector-I 2 K superfluid helium cryogenic system

The Accelerator Driven Sub-critical(ADS)system is a strategic plan to solve the nuclear waste problem for nuclear power plants in China.High-energy particle accelerators and colliders contain long strings of superconducting devices,superconducting radio frequency cavities,and magnets,which may require cooling by 2 K superfluid helium(HeliumⅡ).2 K superfluid helium cryogenic system has become a research hot spot in the field of superconducting accelerators.In this study,the ADS Injector-I 2 K cryogenic system is examined in detail.The cryogenic system scheme design,key equipment,and technology design,such as the 2 K Joule–Thomson(J–T)heat exchanger and cryomodules CM1+CM2 design,are examined,in addition to the commissioning and operation of the cryogenic system.The ADS Injector-I 2 K cryogenic system is the first 100 W superfluid helium system designed and built independently in China.The ADS proton beam reached 10 Me V at 10 m A in July 2016 and 10 Me V at 2 m A in continuous mode in January 2017 and has been operated reliably for over 15,000 h,proving that the design of ADS Injector-I 2 K cryogenic system,the key equipment,and technology research are reasonable,reliable,and meet the requirements.The research into key technologies provides valuable engineering experience that can be helpful for future projects such as CI-ADS(China Initiative Accelerator-Driven System),SHINE(Shanghai High Repetition Rate XFEL and Extreme Light Facility),PAPS(Platform of Advanced Photon Source Technology),and CEPC(Circular Electron-Positron Collider),thereby developing national expertise in the field of superfluid helium cryogenic systems.

Helium,Argon,and Xenon Isotopic Compositions of Ore-forming Fluids in Jinding-Baiyangping Polymetallic Deposits,Yunnan,Southwest China

The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore-forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore-forming fluid is 2.7×10?6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24–3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust-mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding-Baiyangping ore belt.

Thermal-Hydraulic System Study of the Helium Cooled Pebble Bed (HCPB) Test Blanket Module (TBM) for ITER Using System Code RELAP5

The HCPB concept has been a European DEMO reference concept for nearly one decade. Detailed thermal-hydraulic study on the control behavior of the whole system is one of the important parts of this development. The thermal-hydraulic effect of the TBM-combined cooling circuit during a cyclic operation in ITER has been studied using the system code RELAP5. The RELAP5 is based on an one-dimensional, transient two-fluid model for the flow of a two-phase steam-water mixture that can contain noncondensable components like Helium. The RELAP5models are modified to take the cyclic operation of the circulator, heat, exchanger, bypass, valves etc in to account. A sequence of operational phases is investigated, starting from the cold state through the heating phase that brings the system to a stand-by condition, followed by typical power cycles applied in ITER. The results show that the implemented control mechanisms keep the inlet temperature to the TBM and the total mass flow rate at the required values through all phases.