We present a valence orbital method of calculating high-order harmonic generation from a diatomic molecule with arbitrary orientation by using a space rotation operator. We evaluate the effects of each valence orbital...We present a valence orbital method of calculating high-order harmonic generation from a diatomic molecule with arbitrary orientation by using a space rotation operator. We evaluate the effects of each valence orbital on harmonic emissions from N2 and O2 molecules in detail separately. The calculation results confirm the different properties of harmonic yields from N2 and O2 molecules which are well consistent with available experimental data. We observe that due to the orientation dependence of ／sigma and ／pi orbitals, the bonding orbital （π2pz）^2 of N2 determines the maximum of harmonic emission when the molecular axis of N2 is aligned parallel to the laser vector, and the magnitude of the high harmonic signal gradually weakens with the orientation angle of molecular axis increasing. But for O2 molecule the antibonding orbitals （π2pz）^1 and （π2pz）^1 contribute to the maximum of harmonic yield when O2 is aligned at 45° and bonding orbitals （π2pz）^2 and （π2pz）^2 slightly influence the orientation angle of maximum of harmonic radiation not exactly at 45°.展开更多
Recently,it has been realized that in some systems internal space rotation can induce energy amplification for scattered waves,similar to rotation in real space.In particularly,it has been shown that energy extraction...Recently,it has been realized that in some systems internal space rotation can induce energy amplification for scattered waves,similar to rotation in real space.In particularly,it has been shown that energy extraction is possible for a Q-ball,a stationary non-topological soliton that is coherently rotating in its field space.In this paper,we generalize the analysis to the case of boson stars,and show that the same energy extraction mechanism still works for boson stars.展开更多
The betatron matching of a rotationally asymmetric beam in space charge dominated low-energy beam transports （LEBTs） where solenoids are used for the transverse matching has been studied. For better understanding, t...The betatron matching of a rotationally asymmetric beam in space charge dominated low-energy beam transports （LEBTs） where solenoids are used for the transverse matching has been studied. For better understanding, the coupling elements of a beam matrix are interpreted in special forms that are products of a term defined by the Larmor rotation angle and another by the difference between the beam matrix elements in the two transverse planes. The coupling form originally derived from the rotationally symmetric field in solenoids still holds when taking into account the rotationally asymmetric space charge forces that are due to the unequal emittance in the two transverse planes. It is shown in this paper that when an LEBT mainly comprising solenoids transports a beam having unequal emittance in the two transverse planes and the linear space charge force is taken into account, the initial Twiss parameters can be modified to obtain the minimum and equal emittance at the LEBT exit. The TRACE3D calculations also prove the principle. However, when quadrupoles that are also rotationally asymmetric are involved in between solenoids, the coupling between the two transverse planes becomes more complicated and the emittance increase is usually unavoidable. A matching example using the CSNS （China Spallation Neutron Source） LEBT conditions is also presented.展开更多
The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou （HIRFL）. Such a heavy ion beam can be produ...The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou （HIRFL）. Such a heavy ion beam can be produced by non-adiabatic compression, and it is implemented by fast rotation in the longitudinal phase space. In this paper, the possible beam parameters during longitudinal bunch compression are studied by using the envelope model. The result shows that a shortest heavy ion bunch 23Su2S＋ of 29 ns with energy of 200 MeV/u can be obtained, which can satisfy high energy density physics research.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10774033, 60878018 and 10674036)the Program of Excellent Team in Harbin Institute of Technologythe Program for New Century Excellent Talents in University(NCET),China (Grant No. NCET-04-0319)
文摘We present a valence orbital method of calculating high-order harmonic generation from a diatomic molecule with arbitrary orientation by using a space rotation operator. We evaluate the effects of each valence orbital on harmonic emissions from N2 and O2 molecules in detail separately. The calculation results confirm the different properties of harmonic yields from N2 and O2 molecules which are well consistent with available experimental data. We observe that due to the orientation dependence of ／sigma and ／pi orbitals, the bonding orbital （π2pz）^2 of N2 determines the maximum of harmonic emission when the molecular axis of N2 is aligned parallel to the laser vector, and the magnitude of the high harmonic signal gradually weakens with the orientation angle of molecular axis increasing. But for O2 molecule the antibonding orbitals （π2pz）^1 and （π2pz）^1 contribute to the maximum of harmonic yield when O2 is aligned at 45° and bonding orbitals （π2pz）^2 and （π2pz）^2 slightly influence the orientation angle of maximum of harmonic radiation not exactly at 45°.
基金support by the Fundamental Research Funds for the Central Universities(Grant No.WK2030000036)the National Natural Science Foundation of China(Grant Nos.12075233and 12247103)+2 种基金the National Key R&D Program of China(Grant No.2022YFC220010)funded by STFC Consolidated(Grant No.ST/T000732/1)support from the National Natural Science Foundation of China(Grant No.123B1030)。
文摘Recently,it has been realized that in some systems internal space rotation can induce energy amplification for scattered waves,similar to rotation in real space.In particularly,it has been shown that energy extraction is possible for a Q-ball,a stationary non-topological soliton that is coherently rotating in its field space.In this paper,we generalize the analysis to the case of boson stars,and show that the same energy extraction mechanism still works for boson stars.
基金Supported by CAS Knowledge Innovation Program-'CSNS R&D Studies'National Natural Science Foundation of China(10775153)
文摘The betatron matching of a rotationally asymmetric beam in space charge dominated low-energy beam transports （LEBTs） where solenoids are used for the transverse matching has been studied. For better understanding, the coupling elements of a beam matrix are interpreted in special forms that are products of a term defined by the Larmor rotation angle and another by the difference between the beam matrix elements in the two transverse planes. The coupling form originally derived from the rotationally symmetric field in solenoids still holds when taking into account the rotationally asymmetric space charge forces that are due to the unequal emittance in the two transverse planes. It is shown in this paper that when an LEBT mainly comprising solenoids transports a beam having unequal emittance in the two transverse planes and the linear space charge force is taken into account, the initial Twiss parameters can be modified to obtain the minimum and equal emittance at the LEBT exit. The TRACE3D calculations also prove the principle. However, when quadrupoles that are also rotationally asymmetric are involved in between solenoids, the coupling between the two transverse planes becomes more complicated and the emittance increase is usually unavoidable. A matching example using the CSNS （China Spallation Neutron Source） LEBT conditions is also presented.
基金Supported by National Natural Science Foundation of China (10905082)
文摘The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou （HIRFL）. Such a heavy ion beam can be produced by non-adiabatic compression, and it is implemented by fast rotation in the longitudinal phase space. In this paper, the possible beam parameters during longitudinal bunch compression are studied by using the envelope model. The result shows that a shortest heavy ion bunch 23Su2S＋ of 29 ns with energy of 200 MeV/u can be obtained, which can satisfy high energy density physics research.
