X-ray drive asymmetry is one of the main seeds of low-mode implosion asymmetry that blocks further improvement of the nuclear per-formance of“high-foot”experiments on the National Ignition Facility[Miller et al.,Nuc...X-ray drive asymmetry is one of the main seeds of low-mode implosion asymmetry that blocks further improvement of the nuclear per-formance of“high-foot”experiments on the National Ignition Facility[Miller et al.,Nucl.Fusion 44,S228(2004)].More particularly,the P2 asymmetry of Au's M-band flux can also severely influence the implosion performance of ignition capsules[Li et al.,Phys.Plasmas 23,072705(2016)].Here we study the smoothing effect of mid-and/or high-Z dopants in ablator on Au's M-band flux asymmetries,by modeling and comparing the implosion processes of a Ge-doped ignition capsule and a Si-doped one driven by X-ray sources with P2 M-band flux asymmetry.As the results,(1)mid-or high-Z dopants absorb hard X-rays(M-band flux)and re-emit isotropically,which helps to smooth the asymmetric M-band flux arriving at the ablation front,therefore reducing the P2 asymmetries of the imploding shell and hot spot;(2)the smoothing effect of Ge-dopant is more remarkable than Si-dopant because its opacity in Au's M-band is higher than the latter's;and(3)placing the doped layer at a larger radius in ablator is more efficient.Applying this effect may not be a main measure to reduce the low-mode implosion asymmetry,but might be of significance in some critical situations such as inertial confinement fusion(ICF)experiments very near the performance cliffs of asymmetric X-ray drives.展开更多
A preliminary experiment triggering a plasma current quench by laser ablation of high-Z impurities has been performed in the HL-1M tokamak. The injection of impurities with higher electric charges into tokamak plasmas...A preliminary experiment triggering a plasma current quench by laser ablation of high-Z impurities has been performed in the HL-1M tokamak. The injection of impurities with higher electric charges into tokamak plasmas can increase the radiation cooling of the plasma. Resistive, highly radiating plasma formed prior to the thermal quench can dissipate both the thermal and magnetic energies, which is possibly a simple and potential approach to reducing significantly the plasma thermal energy and magnetic energy before a disruption thereby a safe plasma termination is obtained.展开更多
An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are i...An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are investigated numerically. It is found that the positron yield is mainly affected by the number of electrons of energies up to several hundreds of MeV. Using near-critical density targets for electron acceleration, the number of high energy electrons can be increased dramatically. Through start-to-end simulations, it is shown that up to 6.78×10106.78×1010 positrons can be generated with state-of-the-art Joule-class femtosecond laser systems.展开更多
This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point o...This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point of Closest Approach） algorithm reconstructing muon track gives 3D radiography images of the target material. Z-discrimination capability, effects of the placement of high-Z materials, shielding materials inside the cargo, and spatial resolution of position sensitive detector for muon radiography are carefully studied. Our results show that a detector position resolution of 50 μm is good enough for shielded materials detection.展开更多
Radiotherapy(RT)based on X-ray irradiation is a widely applied cancer treatment strategy in the clinic.However,treating cancer based on RT alone usually results in insufficient radiation energy deposition,which inevit...Radiotherapy(RT)based on X-ray irradiation is a widely applied cancer treatment strategy in the clinic.However,treating cancer based on RT alone usually results in insufficient radiation energy deposition,which inevitably has serious side effects on healthy parts of the body.Interestingly,high atomic number(high-Z)metal nanocrystals as X-ray sensitizers can reduce the radiation dose effectively due to their high X-ray absorption,which has attracted increased attention in recent years.High-Z metal nanocrystals produce Auger and photoelectrons electrons under X-ray irradiation,which could generate large amounts of reactive oxygen species,and induce cellular damages.The sensitization effect of high-Z metal nanocrystals is closely related with their composition,morphologies,and size,which would strongly impact their performances in the application of cancer imaging and therapy.In this review,we summarize diverse types of X-ray sensitizers such as bismuth,hafnium,gold,and gadolinium for cancer RT and imaging applications.In addition,current challenges and the outlook of RT based on high-Z metal nanocrystals are also discussed.展开更多
Radiotherapy is a mainstay treatment for malignant tumors in clinical practice.However,enhancing radiation damage to tumor cells meanwhile sparing normal tissues is still a great challenge in radiotherapy.Nanomaterial...Radiotherapy is a mainstay treatment for malignant tumors in clinical practice.However,enhancing radiation damage to tumor cells meanwhile sparing normal tissues is still a great challenge in radiotherapy.Nanomaterials with high atomic number(Z)values are promising radiosensitizers by promoting the radiation energy deposition in irradiated tumor cells,thus enhancing the therapeutic ratio of radiotherapy.In this review,we described the mechanisms of high-Z element based-radiosensitizers and systematically summarized the recent progress on high-Z metal-based nanomaterials,including high-Z metal-based nanoparticles,high-Z metal-based nanoscale metal-organic frameworks and high-Z metal-doping nanomaterials.Finally,further potential and challenges in this field were discussed.展开更多
基金This work is partly supported by the National Natural Science Foundation of China under Grant Nos.11575034,11275031,11475033the Fundamental Research Program of CAEP(Contract No.2013A0102002).
文摘X-ray drive asymmetry is one of the main seeds of low-mode implosion asymmetry that blocks further improvement of the nuclear per-formance of“high-foot”experiments on the National Ignition Facility[Miller et al.,Nucl.Fusion 44,S228(2004)].More particularly,the P2 asymmetry of Au's M-band flux can also severely influence the implosion performance of ignition capsules[Li et al.,Phys.Plasmas 23,072705(2016)].Here we study the smoothing effect of mid-and/or high-Z dopants in ablator on Au's M-band flux asymmetries,by modeling and comparing the implosion processes of a Ge-doped ignition capsule and a Si-doped one driven by X-ray sources with P2 M-band flux asymmetry.As the results,(1)mid-or high-Z dopants absorb hard X-rays(M-band flux)and re-emit isotropically,which helps to smooth the asymmetric M-band flux arriving at the ablation front,therefore reducing the P2 asymmetries of the imploding shell and hot spot;(2)the smoothing effect of Ge-dopant is more remarkable than Si-dopant because its opacity in Au's M-band is higher than the latter's;and(3)placing the doped layer at a larger radius in ablator is more efficient.Applying this effect may not be a main measure to reduce the low-mode implosion asymmetry,but might be of significance in some critical situations such as inertial confinement fusion(ICF)experiments very near the performance cliffs of asymmetric X-ray drives.
基金Project supported by IAEA International Science Foundation （Grant No IS 105123）.
文摘A preliminary experiment triggering a plasma current quench by laser ablation of high-Z impurities has been performed in the HL-1M tokamak. The injection of impurities with higher electric charges into tokamak plasmas can increase the radiation cooling of the plasma. Resistive, highly radiating plasma formed prior to the thermal quench can dissipate both the thermal and magnetic energies, which is possibly a simple and potential approach to reducing significantly the plasma thermal energy and magnetic energy before a disruption thereby a safe plasma termination is obtained.
基金Supported by the National Basic Research Program of China under Grant No 2013CBA01502the National Natural Science Foundation of China under Grant Nos 11575011 and 11535001+1 种基金the National Grand Instrument Project under Grant No2012YQ030142the UK EPSRC under Grant Nos EP/G054950/1,EP/G056803/1,EP/G055165/1 and EP/M022463/1
文摘An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are investigated numerically. It is found that the positron yield is mainly affected by the number of electrons of energies up to several hundreds of MeV. Using near-critical density targets for electron acceleration, the number of high energy electrons can be increased dramatically. Through start-to-end simulations, it is shown that up to 6.78×10106.78×1010 positrons can be generated with state-of-the-art Joule-class femtosecond laser systems.
基金Supported by National Natural Science Foundation of China (10575046,10775062)Program for New Century Excellent Talents in University
文摘This paper studies the possibility of using the scattering of cosmic muons to identify threatening high-Z materials. Various scenarios of threat material detection are simulated with the Geant4 toolkit. PoCA （Point of Closest Approach） algorithm reconstructing muon track gives 3D radiography images of the target material. Z-discrimination capability, effects of the placement of high-Z materials, shielding materials inside the cargo, and spatial resolution of position sensitive detector for muon radiography are carefully studied. Our results show that a detector position resolution of 50 μm is good enough for shielded materials detection.
基金We gratefully acknowledge support by the National Natural Science Foundation of China(Nos.21674116 and 21874024)the joint research projects of Health and Education Commission of Fujian Province(No.2019-WJ-20).
文摘Radiotherapy(RT)based on X-ray irradiation is a widely applied cancer treatment strategy in the clinic.However,treating cancer based on RT alone usually results in insufficient radiation energy deposition,which inevitably has serious side effects on healthy parts of the body.Interestingly,high atomic number(high-Z)metal nanocrystals as X-ray sensitizers can reduce the radiation dose effectively due to their high X-ray absorption,which has attracted increased attention in recent years.High-Z metal nanocrystals produce Auger and photoelectrons electrons under X-ray irradiation,which could generate large amounts of reactive oxygen species,and induce cellular damages.The sensitization effect of high-Z metal nanocrystals is closely related with their composition,morphologies,and size,which would strongly impact their performances in the application of cancer imaging and therapy.In this review,we summarize diverse types of X-ray sensitizers such as bismuth,hafnium,gold,and gadolinium for cancer RT and imaging applications.In addition,current challenges and the outlook of RT based on high-Z metal nanocrystals are also discussed.
基金supported by the National Natural Science Foundation of China(Nos.82172762,21904119,31900991,82073395)the Innovation Talent Support Program of Henan Province(No.21HASTIT043)+1 种基金the Postdoctoral Science Foundation of China(Nos.2020TQ0288,2021M690140)the Postdoctoral Innovative Talent Support Program of Henan Province(No.ZYYCYU202012179).
文摘Radiotherapy is a mainstay treatment for malignant tumors in clinical practice.However,enhancing radiation damage to tumor cells meanwhile sparing normal tissues is still a great challenge in radiotherapy.Nanomaterials with high atomic number(Z)values are promising radiosensitizers by promoting the radiation energy deposition in irradiated tumor cells,thus enhancing the therapeutic ratio of radiotherapy.In this review,we described the mechanisms of high-Z element based-radiosensitizers and systematically summarized the recent progress on high-Z metal-based nanomaterials,including high-Z metal-based nanoparticles,high-Z metal-based nanoscale metal-organic frameworks and high-Z metal-doping nanomaterials.Finally,further potential and challenges in this field were discussed.
