Using a laser vaporization/pulsed molecular beam source,photoionization time-of-flight mass spectra of bare aluminum clusters Aln(n up to larger than 70)and of carbon-,oxygen-,and hydrogen-adducted aluminum clusters-a...Using a laser vaporization/pulsed molecular beam source,photoionization time-of-flight mass spectra of bare aluminum clusters Aln(n up to larger than 70)and of carbon-,oxygen-,and hydrogen-adducted aluminum clusters-associated complexes are detected.The cause of the observed odd-even alternation in reactivity of Aln and the formation mechanism of the informative products are discussed.展开更多
Photoionization time of flight mass spectra of bare aluminum and aluminum-carbon mixed clusters as well as a variety of oxygen-and oxygen-carbon-adducted aluminum clusters are recorded and assigned.The discontinuities...Photoionization time of flight mass spectra of bare aluminum and aluminum-carbon mixed clusters as well as a variety of oxygen-and oxygen-carbon-adducted aluminum clusters are recorded and assigned.The discontinuities in the mass abundance spectra at AI_(7),AI_(13),AI_(23),AI_(7)C,AI_(13)C,and AI_(24)C are revealed.The findings are interpreted in terms of the electronic and geometric structures of these species.展开更多
This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led ...This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5 nm in radius and the laser intensity used was 3 × 10^17 W/cm^2.The measured maximum and average energies of deuterons produced in the laser-cluster interaction were 60 and 13.5 keV, respectively. Prom DD collisions of energetic deuterons, a yield of 2.5（±0.4） × 10^4 fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 × 10^5 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.展开更多
The interaction of intense femtosecond laser pulses with hydrogen clusters has been experimentally studied. The hydrogen clusters were produced from expansion of high-pressure hydrogen gas （backed up to 8×10^6Pa...The interaction of intense femtosecond laser pulses with hydrogen clusters has been experimentally studied. The hydrogen clusters were produced from expansion of high-pressure hydrogen gas （backed up to 8×10^6Pa） into vacuum through a conical nozzle cryogenically cooled by liquid nitrogen. The average size of hydrogen clusters was estimated by Rayleigh scattering measurement and the maximum proton energy of up to 4.2keV has been obtained from the Coulomb explosion of hydrogen clusters under 2 × 10^16W/cm^2 laser irradiation. Dependence of the maximum proton energy on cluster size and laser intensity was investigated, indicating the correlation between the laser intensity and the cluster size. The maximum proton energy is found to be directly proportional to the laser intensity, which is consistent with the theoretical prediction.展开更多
The effect of the laser spot size on the neutron yield of table-top nuclear fusion from explosions of a femtosecond intense laser pulse heated deuterium clusters is investigated by using a simplified model, in which t...The effect of the laser spot size on the neutron yield of table-top nuclear fusion from explosions of a femtosecond intense laser pulse heated deuterium clusters is investigated by using a simplified model, in which the cluster size distribution and the energy attenuation of the laser as it propagates through the cluster jet are taken into account. It has been found that there exists a proper laser spot size for the maximum fusion neutron yield for a given laser pulse and a specific deuterium gas cluster jet. The proper spot size, which is dependent on the laser parameters and the cluster jet parameters, has been calculated and compared with the available experimental data. A reasonable agreement between the calculated results and the published experimental results is found.展开更多
The simulations of three-dimensional particle dynamics show that when irradiated by an ultrashort intense laser pulse, the deuterated methane cluster expands and the majority of deuterons overrun the more slowly expan...The simulations of three-dimensional particle dynamics show that when irradiated by an ultrashort intense laser pulse, the deuterated methane cluster expands and the majority of deuterons overrun the more slowly expanding carbon ions, resulting in the creation of two separated subelusters. The enhanced deuteron kinetic energy and a narrow peak around the energy maximum in the deuteron energy distribution make a considerable contribution to the efficiency of nuclear fusion compared with the ease of homonuelear deuterium clusters. With the intense laser irradiation, the nuclear fusion yield increases with the increase of the cluster size, so that deuterated heteronuelear clusters with larger sizes are required to achieve a greater neutron yield.展开更多
基金Supported by the National Natural Science Foundation of China under Grants Nos.19574059 and 19634030by the Joint Laboratory for Quantum Optics,Chinese Academy of Sciences.
文摘Using a laser vaporization/pulsed molecular beam source,photoionization time-of-flight mass spectra of bare aluminum clusters Aln(n up to larger than 70)and of carbon-,oxygen-,and hydrogen-adducted aluminum clusters-associated complexes are detected.The cause of the observed odd-even alternation in reactivity of Aln and the formation mechanism of the informative products are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19574059 and 19634030,and in part by the Joint Laboratory for Quantum Optics,Chinese Academy of Sciences.
文摘Photoionization time of flight mass spectra of bare aluminum and aluminum-carbon mixed clusters as well as a variety of oxygen-and oxygen-carbon-adducted aluminum clusters are recorded and assigned.The discontinuities in the mass abundance spectra at AI_(7),AI_(13),AI_(23),AI_(7)C,AI_(13)C,and AI_(24)C are revealed.The findings are interpreted in terms of the electronic and geometric structures of these species.
基金supported by the National Basic Research Program of China (Grant No 2006CB806000)the National Natural Science Foundation of China (Grant No 10535070)
文摘This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5 nm in radius and the laser intensity used was 3 × 10^17 W/cm^2.The measured maximum and average energies of deuterons produced in the laser-cluster interaction were 60 and 13.5 keV, respectively. Prom DD collisions of energetic deuterons, a yield of 2.5（±0.4） × 10^4 fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 × 10^5 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.
文摘The interaction of intense femtosecond laser pulses with hydrogen clusters has been experimentally studied. The hydrogen clusters were produced from expansion of high-pressure hydrogen gas （backed up to 8×10^6Pa） into vacuum through a conical nozzle cryogenically cooled by liquid nitrogen. The average size of hydrogen clusters was estimated by Rayleigh scattering measurement and the maximum proton energy of up to 4.2keV has been obtained from the Coulomb explosion of hydrogen clusters under 2 × 10^16W/cm^2 laser irradiation. Dependence of the maximum proton energy on cluster size and laser intensity was investigated, indicating the correlation between the laser intensity and the cluster size. The maximum proton energy is found to be directly proportional to the laser intensity, which is consistent with the theoretical prediction.
基金Project supported by the National Basic Research Program of China (Grant No 2006CB806000)the National Natural Science Foundation of China (Grant No 10535070)
文摘The effect of the laser spot size on the neutron yield of table-top nuclear fusion from explosions of a femtosecond intense laser pulse heated deuterium clusters is investigated by using a simplified model, in which the cluster size distribution and the energy attenuation of the laser as it propagates through the cluster jet are taken into account. It has been found that there exists a proper laser spot size for the maximum fusion neutron yield for a given laser pulse and a specific deuterium gas cluster jet. The proper spot size, which is dependent on the laser parameters and the cluster jet parameters, has been calculated and compared with the available experimental data. A reasonable agreement between the calculated results and the published experimental results is found.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10535070 and 10674145)the National Basic Research Program of China (Grant No 2006CB806000)the Shanghai Supercomputer Center (SSC)
文摘The simulations of three-dimensional particle dynamics show that when irradiated by an ultrashort intense laser pulse, the deuterated methane cluster expands and the majority of deuterons overrun the more slowly expanding carbon ions, resulting in the creation of two separated subelusters. The enhanced deuteron kinetic energy and a narrow peak around the energy maximum in the deuteron energy distribution make a considerable contribution to the efficiency of nuclear fusion compared with the ease of homonuelear deuterium clusters. With the intense laser irradiation, the nuclear fusion yield increases with the increase of the cluster size, so that deuterated heteronuelear clusters with larger sizes are required to achieve a greater neutron yield.
