One of the most fascinating ignition schemes for the inertial fusion energy that might be feasible is fast ignition. Its targets are ignited on the outside surface so there is no need to low density and high temperatu...One of the most fascinating ignition schemes for the inertial fusion energy that might be feasible is fast ignition. Its targets are ignited on the outside surface so there is no need to low density and high temperature center is required by central hot spot ignition. Fast ignition concept is noteworthy for a simple but fundamental reason： In principle it requires less total energy input to achieve ignition. In this paper, fuel energy and fuel energy gain of nearly pure deuterium capsule are calculated. This capsule is ignited by a deuterium-tritium seed, which would reduce the tritium inventory to a few percentages. The variations of fuel energy gain versus fuel density have been studied and submitted. On the basis of different physical parameters the following results of the investigation are presented and discussed. The energy gain curves for different tritium concentrations are found and limiting gain curves are derived. Finally, tritium-poor fast ignitor is compared to equimolar deuterium-tritium fast ignitor.展开更多
In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact ...In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact size.However,it is still challenging to simultaneously enhance their quality and yield for practical applications such as fast ion ignition of inertial confinement fusion.Compared with other mechanisms of laser-driven ion acceleration,the hole-boring radiation pressure acceleration has a special advantage in generating high-fluence ion beams suitable for the creation of high energy density state of matters.In this paper,we present a review on some theoretical and numerical studies of the hole-boring radiation pressure acceleration.First we discuss the typical field structure associated with this mechanism,its intrinsic feature of oscillations,and the underling physics.Then we will review some recently proposed schemes to enhance the beam quality and the efficiency in the hole-boring radiation pressure acceleration,such as matching laser intensity profile with target density profile,and using two-ion-species targets.Based on this,we propose an integrated scheme for efficient high-quality hole-boring radiation pressure acceleration,in which the longitudinal density profile of a composite target as well as the laser transverse intensity profile are tailored according to the matching condition.展开更多
A fundamental difference of very high intensity laser interaction with plasmas from solid targets appears with lasing at picosecond （ps） pulse durations in contrast to pulses of nanosec-onds （ns）. This can be seen...A fundamental difference of very high intensity laser interaction with plasmas from solid targets appears with lasing at picosecond （ps） pulse durations in contrast to pulses of nanosec-onds （ns）. This can be seen from the more than 10,000 times higher acceleration with ps pulse du-rations than with thermal pressure determined interaction. A ps pulse duration produces instantly acting high-efficiency nonlinear （ponderomotive） electrodynamic force dominated acceleration in contrast to heating with longer pulses. The ps pulses accelerate high-density plasma blocks. This can be used by a new scheme of side-on driven laser fusion with generating a flame ignition in uncompressed fusion fuel of solid density resulting in a reaction velocity of more than 2000 km/s for DT.展开更多
Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil insid...Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil inside the cone has been considered.Proton acceleration is driven by a 10^(20) W·cm^(-2) and 1 ps laser pulse focused on the hydrogen foil.Simulations show an important surface current at the cone walls which generates a magnetic field.This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip.As a result,a tens of kT B z field is set up at the cone tip,which is strong enough to deflect the protons and increase the beam divergence substantially.We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence.展开更多
In the double-cone ignition scheme of inertial confinement fusion,the head-on collision of two compressed fuel jets from the cone-tips forms an isochoric plasma,which is then heated suddenly by a MeV relativistic elec...In the double-cone ignition scheme of inertial confinement fusion,the head-on collision of two compressed fuel jets from the cone-tips forms an isochoric plasma,which is then heated suddenly by a MeV relativistic electron beam produced by ultra-intense picosecond laser pulses.This fast-heating process was studied experimentally at the ShenguangⅡupgrade laser facility.By observing temporal-resolved X-ray emission and the spatial-resolved X-ray spectrum,the colliding process and heating process are carefully studied.The colliding plasma was imaged to have dimensions of approximately86μm in the implosion direction and approximately 120μm in the heating direction.By comparing the simulated plasma X-ray spectrum with experimental data,the electron temperature of the heated plasma was found to rapidly increase to 600±50 eV,almost doubling the temperature achieved before the heating laser incidence.展开更多
In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we empl...In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma.It is found that the wavelength of 0.53 μm and the intensity of about 1020W/cm^2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances.展开更多
The transport process of a relativistic electron beam(REB)in high-density and degenerate plasmas holds significant importance for fast ignition.In this study,we have formulated a comprehensive theoretical model to add...The transport process of a relativistic electron beam(REB)in high-density and degenerate plasmas holds significant importance for fast ignition.In this study,we have formulated a comprehensive theoretical model to address this issue,incorporating quantum degeneracy,charged particle collisions and the effects of electromagnetic(EB)fields.We model the fuel as a uniform density region and particularly focus on the effect of quantum degeneracy during the transport of the REB,which leads to the rapid growth of a self-generated EB field and a subsequently significant self-organized pinching of the REB.Through our newly developed hybrid particle-in-cell simulations,we have observed a two-fold enhancement of the heating efficiency of the REB compared with previous intuitive expectation.This finding provides a promising theoretical framework for exploring the degeneracy effect and the enhanced self-generated EB field in the dense plasma for fast ignition,and is also linked to a wide array of ultra-intense laser-based applications.展开更多
Energetic materials are solids that release a large amount of energy in combustion. The evaluation depends on both combustion heat and ignition temperature. Conventional non-metallic materials have low ignition temper...Energetic materials are solids that release a large amount of energy in combustion. The evaluation depends on both combustion heat and ignition temperature. Conventional non-metallic materials have low ignition temperature but small combustion heat,whereas metals have large combustion heat but high ignition temperatures. We show that many metallic glasses, combining the merits of both metals and non-metals, have large combustion heat, approximately twice that of the non-metals, and low ignition temperature that is several hundreds of Kelvin lower than that of the metals. The ease in igniting metallic glass results from the low thermal conductivity of the materials and the storage of energy in their liquid-like atomic structure. Metallic glass ribbons outweigh metallic nanoparticles due to their high production efficiency, low cost and nontoxicity. The findings suggest that metallic glasses are alternative energetic materials.展开更多
The laser-induced relativistic shock waves are described. The shock waves can be created directly by a high irradiance laser or indirectly by a laser acceleration of a foil that collides with a second static foil. A s...The laser-induced relativistic shock waves are described. The shock waves can be created directly by a high irradiance laser or indirectly by a laser acceleration of a foil that collides with a second static foil. A special case of interest is the creation of laser-induced fusion where the created alpha particles create a detonation wave. A novel application is suggested with the shock wave or the detonation wave to ignite a pre-compressed target. In particular, the deuterium–tritium fusion is considered. It is suggested that the collision of two laser accelerated foils might serve as a novel relativistic accelerator for bulk material collisions.展开更多
文摘One of the most fascinating ignition schemes for the inertial fusion energy that might be feasible is fast ignition. Its targets are ignited on the outside surface so there is no need to low density and high temperature center is required by central hot spot ignition. Fast ignition concept is noteworthy for a simple but fundamental reason： In principle it requires less total energy input to achieve ignition. In this paper, fuel energy and fuel energy gain of nearly pure deuterium capsule are calculated. This capsule is ignited by a deuterium-tritium seed, which would reduce the tritium inventory to a few percentages. The variations of fuel energy gain versus fuel density have been studied and submitted. On the basis of different physical parameters the following results of the investigation are presented and discussed. The energy gain curves for different tritium concentrations are found and limiting gain curves are derived. Finally, tritium-poor fast ignitor is compared to equimolar deuterium-tritium fast ignitor.
基金This work was supported in part by the National Basic Research Program of China(Grant No.2013CBA01504)the National Natural Science Foundation of China(Grant Nos.11675108,11421064,11405108 and 11374210).
文摘In contrast to ion beams produced by conventional accelerators,ion beams accelerated by ultrashort intense laser pulses have advantages of ultrashort bunch duration and ultrahigh density,which are achieved in compact size.However,it is still challenging to simultaneously enhance their quality and yield for practical applications such as fast ion ignition of inertial confinement fusion.Compared with other mechanisms of laser-driven ion acceleration,the hole-boring radiation pressure acceleration has a special advantage in generating high-fluence ion beams suitable for the creation of high energy density state of matters.In this paper,we present a review on some theoretical and numerical studies of the hole-boring radiation pressure acceleration.First we discuss the typical field structure associated with this mechanism,its intrinsic feature of oscillations,and the underling physics.Then we will review some recently proposed schemes to enhance the beam quality and the efficiency in the hole-boring radiation pressure acceleration,such as matching laser intensity profile with target density profile,and using two-ion-species targets.Based on this,we propose an integrated scheme for efficient high-quality hole-boring radiation pressure acceleration,in which the longitudinal density profile of a composite target as well as the laser transverse intensity profile are tailored according to the matching condition.
文摘A fundamental difference of very high intensity laser interaction with plasmas from solid targets appears with lasing at picosecond （ps） pulse durations in contrast to pulses of nanosec-onds （ns）. This can be seen from the more than 10,000 times higher acceleration with ps pulse du-rations than with thermal pressure determined interaction. A ps pulse duration produces instantly acting high-efficiency nonlinear （ponderomotive） electrodynamic force dominated acceleration in contrast to heating with longer pulses. The ps pulses accelerate high-density plasma blocks. This can be used by a new scheme of side-on driven laser fusion with generating a flame ignition in uncompressed fusion fuel of solid density resulting in a reaction velocity of more than 2000 km/s for DT.
基金This work has been partially supported by the grant numberENE2014-54960-R of the Spanish Ministry of Economy andCompetitivenessthe COST Action MP1208 and the Co-ordinated Research Project of IAEA F13016.
文摘Proton generation,transport and interaction with hollow cone targets are investigated by means of two-dimensional PIC simulations.A scaled-down hollow cone with gold walls,a carbon tip and a curved hydrogen foil inside the cone has been considered.Proton acceleration is driven by a 10^(20) W·cm^(-2) and 1 ps laser pulse focused on the hydrogen foil.Simulations show an important surface current at the cone walls which generates a magnetic field.This magnetic field is dragged by the quasi-neutral plasma formed by fast protons and co-moving electrons when they propagate towards the cone tip.As a result,a tens of kT B z field is set up at the cone tip,which is strong enough to deflect the protons and increase the beam divergence substantially.We propose using heavy materials at the cone tip and increasing the laser intensity in order to mitigate magnetic field generation and proton beam divergence.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25010100,XDA25010300 and XDA25030100)in part by the National Natural Science Foundation of China(Grants No.11827807)。
文摘In the double-cone ignition scheme of inertial confinement fusion,the head-on collision of two compressed fuel jets from the cone-tips forms an isochoric plasma,which is then heated suddenly by a MeV relativistic electron beam produced by ultra-intense picosecond laser pulses.This fast-heating process was studied experimentally at the ShenguangⅡupgrade laser facility.By observing temporal-resolved X-ray emission and the spatial-resolved X-ray spectrum,the colliding process and heating process are carefully studied.The colliding plasma was imaged to have dimensions of approximately86μm in the implosion direction and approximately 120μm in the heating direction.By comparing the simulated plasma X-ray spectrum with experimental data,the electron temperature of the heated plasma was found to rapidly increase to 600±50 eV,almost doubling the temperature achieved before the heating laser incidence.
基金Supported by the Research Council of University of Guilan
文摘In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma.It is found that the wavelength of 0.53 μm and the intensity of about 1020W/cm^2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25010100 and XDA25050500)the National Natural Science Foundation of China(Grant No.12075204)+1 种基金the Shanghai Municipal Science and Technology Key Project(Grant No.22JC1401500)Dong Wu acknowledges the sponsorship of the Yangyang Development Fund。
文摘The transport process of a relativistic electron beam(REB)in high-density and degenerate plasmas holds significant importance for fast ignition.In this study,we have formulated a comprehensive theoretical model to address this issue,incorporating quantum degeneracy,charged particle collisions and the effects of electromagnetic(EB)fields.We model the fuel as a uniform density region and particularly focus on the effect of quantum degeneracy during the transport of the REB,which leads to the rapid growth of a self-generated EB field and a subsequently significant self-organized pinching of the REB.Through our newly developed hybrid particle-in-cell simulations,we have observed a two-fold enhancement of the heating efficiency of the REB compared with previous intuitive expectation.This finding provides a promising theoretical framework for exploring the degeneracy effect and the enhanced self-generated EB field in the dense plasma for fast ignition,and is also linked to a wide array of ultra-intense laser-based applications.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB30000000)the National Key Research and Development Plan (Grant No. 2018YFA0703603)+1 种基金the National Natural Science Foundation of China (Grant Nos. 11790291, 61999102, 61888102, 51871234, and 51971238)the Natural Science Foundation of Guangdong Province (Grant No. 2019B030302010)
文摘Energetic materials are solids that release a large amount of energy in combustion. The evaluation depends on both combustion heat and ignition temperature. Conventional non-metallic materials have low ignition temperature but small combustion heat,whereas metals have large combustion heat but high ignition temperatures. We show that many metallic glasses, combining the merits of both metals and non-metals, have large combustion heat, approximately twice that of the non-metals, and low ignition temperature that is several hundreds of Kelvin lower than that of the metals. The ease in igniting metallic glass results from the low thermal conductivity of the materials and the storage of energy in their liquid-like atomic structure. Metallic glass ribbons outweigh metallic nanoparticles due to their high production efficiency, low cost and nontoxicity. The findings suggest that metallic glasses are alternative energetic materials.
文摘The laser-induced relativistic shock waves are described. The shock waves can be created directly by a high irradiance laser or indirectly by a laser acceleration of a foil that collides with a second static foil. A special case of interest is the creation of laser-induced fusion where the created alpha particles create a detonation wave. A novel application is suggested with the shock wave or the detonation wave to ignite a pre-compressed target. In particular, the deuterium–tritium fusion is considered. It is suggested that the collision of two laser accelerated foils might serve as a novel relativistic accelerator for bulk material collisions.
