Investigating deuteron–deuteron(DD)fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics.In this study,we experimentally investigated such ...Investigating deuteron–deuteron(DD)fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics.In this study,we experimentally investigated such reactions,using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility.This work focused on the application of range-filter(RF)spectrometers,assembled from a 70 lm aluminum filter and two CR-39 nuclear track detectors,to measure the yields of primary DD-protons.Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers,an approximate primary DD-proton yield of(8.5±1.7)×10^6 was obtained,consistent with the yields from similar laser facilities worldwide.This indicates that the RF spectrometer is an effective way to measure primary DD-protons.However,due to the low yields of D^3He-protons and its small track diameter,CR-39 detectors were unable to distinguish it from the background spots.Using other accurate detectors may help to measure these rare events.展开更多
In inertial confinement fusion experiments,fuel quality is determined mainly by the thermal environment of the capsule in the layering procedure.Owing to the absence of a radial thermal gradient,formed deuterium–deut...In inertial confinement fusion experiments,fuel quality is determined mainly by the thermal environment of the capsule in the layering procedure.Owing to the absence of a radial thermal gradient,formed deuterium–deuterium(DD)ice shells in the capsule are thermally instable.To obtain a solid DD layer with good quality and long lifetime,stringent demands must be placed on the thermal performance of cryogenic targets.In DD cryogenic target preparation,two issues arise,even after the capsule’s temperature uniformity has been improved by the use of thick aluminized films.The first is the inconsistent ice shape,which is related to the capsule’s thermal field.In this article,some typical fabrication details are investigated,including adhesive penetration during assembly,the presence of the fill tube,the optical properties of the hohlraum and film surfaces,the jacket–hohlraum connection,deviations in capsule location,and asymmetrical contact at the arm–jacket interfaces.Detailed comparisons of the thermal effects of these factors provide guidance for target optimization.The second issue is the instability of seeding crystals in the fill tube due to unsteadiness of the direction of the thermal gradient in the fill tube assembly.An additional thermal controller is proposed,analyzed,and optimized to provide robust controllability of tube temperature.The analysis results and optimization methods presented in this article should not only help in dealing with thermal issues associated with DD cryogenic targets,but also provide important references for engineering design of other cryogenic targets.展开更多
Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to te...Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to test the accessibility to the future fusion plant.To self-consistently simulate burning plasmas with profile changes in pellet injection scenarios and to estimate the corresponding burning fraction,a one-dimensional multi-species radial transport model is developed in the BOUT++framework.Several pellet-fueling scenarios are then tested in the model.The results show that the increased fueling depth improves the burning fraction by particle confinement improvement and fusion power increase.Nevertheless,by increasing the depth,the pellet cooling-down may significantly lower the temperature in the core region.Taking the density perturbation into consideration,the reasonable parameters of the fueling scenario in these simulations are estimated as pellet radius r_(p)=3 mm,injection rate=4 Hz,and pellet injection velocity=1000–2000 m s^(-1) without drift or 450 m s^(-1) with high-field-side drift.展开更多
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB160203)the National Natural Science Foundation of China(Nos.11875311 and 11421505).
文摘Investigating deuteron–deuteron(DD)fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics.In this study,we experimentally investigated such reactions,using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility.This work focused on the application of range-filter(RF)spectrometers,assembled from a 70 lm aluminum filter and two CR-39 nuclear track detectors,to measure the yields of primary DD-protons.Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers,an approximate primary DD-proton yield of(8.5±1.7)×10^6 was obtained,consistent with the yields from similar laser facilities worldwide.This indicates that the RF spectrometer is an effective way to measure primary DD-protons.However,due to the low yields of D^3He-protons and its small track diameter,CR-39 detectors were unable to distinguish it from the background spots.Using other accurate detectors may help to measure these rare events.
基金supported by the Science Challenge Project(Grant No.TZ2018006)the National Natural Science Foundation of China(Grant Nos.11804318 and 61803354)+1 种基金the Key Laboratory Foundation of Ultra-Precision Manufacturing(Grant No.ZD18007)the Young Talent Foundation(Grant No.RCFCZ3-2019-5)。
文摘In inertial confinement fusion experiments,fuel quality is determined mainly by the thermal environment of the capsule in the layering procedure.Owing to the absence of a radial thermal gradient,formed deuterium–deuterium(DD)ice shells in the capsule are thermally instable.To obtain a solid DD layer with good quality and long lifetime,stringent demands must be placed on the thermal performance of cryogenic targets.In DD cryogenic target preparation,two issues arise,even after the capsule’s temperature uniformity has been improved by the use of thick aluminized films.The first is the inconsistent ice shape,which is related to the capsule’s thermal field.In this article,some typical fabrication details are investigated,including adhesive penetration during assembly,the presence of the fill tube,the optical properties of the hohlraum and film surfaces,the jacket–hohlraum connection,deviations in capsule location,and asymmetrical contact at the arm–jacket interfaces.Detailed comparisons of the thermal effects of these factors provide guidance for target optimization.The second issue is the instability of seeding crystals in the fill tube due to unsteadiness of the direction of the thermal gradient in the fill tube assembly.An additional thermal controller is proposed,analyzed,and optimized to provide robust controllability of tube temperature.The analysis results and optimization methods presented in this article should not only help in dealing with thermal issues associated with DD cryogenic targets,but also provide important references for engineering design of other cryogenic targets.
基金supported by National Natural Science Foundation of China(Nos.11975087 and 41674165)the National Key Research and Development Program of China(Nos.2017YFE0300501 and 2018YFE030310)。
文摘Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to test the accessibility to the future fusion plant.To self-consistently simulate burning plasmas with profile changes in pellet injection scenarios and to estimate the corresponding burning fraction,a one-dimensional multi-species radial transport model is developed in the BOUT++framework.Several pellet-fueling scenarios are then tested in the model.The results show that the increased fueling depth improves the burning fraction by particle confinement improvement and fusion power increase.Nevertheless,by increasing the depth,the pellet cooling-down may significantly lower the temperature in the core region.Taking the density perturbation into consideration,the reasonable parameters of the fueling scenario in these simulations are estimated as pellet radius r_(p)=3 mm,injection rate=4 Hz,and pellet injection velocity=1000–2000 m s^(-1) without drift or 450 m s^(-1) with high-field-side drift.
