The multi-charged sulfur ions of Sq^＋ （q ≤ 6） have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 10^10- 10^12W.cm^-2. S^6＋ is the ...The multi-charged sulfur ions of Sq^＋ （q ≤ 6） have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 10^10- 10^12W.cm^-2. S^6＋ is the dominant multicharged species at 1064 nm, while S^4＋, S^3＋ and S^2＋ ions are the main multi-charged species at 532 nm. A three-step model （i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing） is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to λ2,λA being the laser wavelength.展开更多
We study the effect of intense laser radiation on the surface of silicate glass prior irradiated by gamma radiation. Experimental results show that the gamma radiation with dose 5 × 104 R leads to the degradation...We study the effect of intense laser radiation on the surface of silicate glass prior irradiated by gamma radiation. Experimental results show that the gamma radiation with dose 5 × 104 R leads to the degradation of the surface resistance of this optical dielectric to electromagnetic radiation. Depending on the dose of the radiation the laser radiation can result in either surface erosion or its pronounced cracking. It is also found that the efficiency of the degradation process is determined not only by the radiation dose, but also by the presence of different impurities in the glass.展开更多
Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to gene...Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to generate milliampere multi-charged helium He2＋ ion beam with a 2.45 GHz electron cyclotron resonance ion source （ECRIS） was tested recently. A design using a specfic permanent magnet 2.45 GHz ECRIS （PMECRIS） source （ERCIS） is reported and the He2~ beam production ability is described. With this source, we produced a total helium beam of 40 mA at 40 kV with 180 W of net microwave power and a gas flow of less than 0.5 seem. At steady state the He2＋ beam intensity is 4.4 rnA, that being the fraction of multi-charged he- lium ion beam is at approximately 11%.展开更多
As is known, GaP is a kind of semiconductors with a wide, indirect gap and is one ofthe dominant materials for fabrication of green luminescence emission diode. It is inevita-ble to form iron impurities in growing the...As is known, GaP is a kind of semiconductors with a wide, indirect gap and is one ofthe dominant materials for fabrication of green luminescence emission diode. It is inevita-ble to form iron impurities in growing the single crystal of GaP. This causes difficulties inimproving the efficiency of the luminesence devices. Undoubtedly, it is very important展开更多
Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-stat...Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-states of Ar(q>8)were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter.To investigate possible enhancements with broadband microwave radiation,a'white'Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of～200MHz.The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region.However,the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned off the flat-B region.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 20573111） and partly supported by the Center for Computational Science, Hefei Institutes of Physical Sciences, China （Grant No 0331405002）.
文摘The multi-charged sulfur ions of Sq^＋ （q ≤ 6） have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 10^10- 10^12W.cm^-2. S^6＋ is the dominant multicharged species at 1064 nm, while S^4＋, S^3＋ and S^2＋ ions are the main multi-charged species at 532 nm. A three-step model （i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing） is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to λ2,λA being the laser wavelength.
文摘We study the effect of intense laser radiation on the surface of silicate glass prior irradiated by gamma radiation. Experimental results show that the gamma radiation with dose 5 × 104 R leads to the degradation of the surface resistance of this optical dielectric to electromagnetic radiation. Depending on the dose of the radiation the laser radiation can result in either surface erosion or its pronounced cracking. It is also found that the efficiency of the degradation process is determined not only by the radiation dose, but also by the presence of different impurities in the glass.
基金supported by the National Natural Science Foundation of China(Grant Nos.11075008 and 11175009)
文摘Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to generate milliampere multi-charged helium He2＋ ion beam with a 2.45 GHz electron cyclotron resonance ion source （ECRIS） was tested recently. A design using a specfic permanent magnet 2.45 GHz ECRIS （PMECRIS） source （ERCIS） is reported and the He2~ beam production ability is described. With this source, we produced a total helium beam of 40 mA at 40 kV with 180 W of net microwave power and a gas flow of less than 0.5 seem. At steady state the He2＋ beam intensity is 4.4 rnA, that being the fraction of multi-charged he- lium ion beam is at approximately 11%.
文摘As is known, GaP is a kind of semiconductors with a wide, indirect gap and is one ofthe dominant materials for fabrication of green luminescence emission diode. It is inevita-ble to form iron impurities in growing the single crystal of GaP. This causes difficulties inimproving the efficiency of the luminesence devices. Undoubtedly, it is very important
基金Supported by the U.S.Department of Energy under contract DE-AC05-00OR22725 with UT-Battelle,LLC
文摘Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-states of Ar(q>8)were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter.To investigate possible enhancements with broadband microwave radiation,a'white'Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of～200MHz.The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region.However,the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned off the flat-B region.
