Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scannin...Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.展开更多
The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory(NSRL)is a diffraction-limited storage ring(DLSR),which plans to use a full energy linac as the injector.To ensure inject...The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory(NSRL)is a diffraction-limited storage ring(DLSR),which plans to use a full energy linac as the injector.To ensure injection efficiency,the injection beam needs to have low emittance.Therefore,a photocathode radio frequency(RF)gun was developed in the HALF R&D project.The gun is designed to deliver high-quality electron bunches with a typically 0.5 nC charge and~4.5 MeV energy with low emittance.The initial system commission with an electron beam was completed at the end of 2020,and a stable 1.2–1.4 mm.mrad emittance with a bunch charge of 500 pC was demonstrated.In this paper,we report the experimental results and experience obtained during the commission,including the RF gun,drive laser system,and beam diagnostics.展开更多
The measurement of mass,or equivalently the binding energy,of exotic nuclei has reached the limits of nuclear existence,which are characterized by tiny production cross-sections and short half-lives.The isochronousmod...The measurement of mass,or equivalently the binding energy,of exotic nuclei has reached the limits of nuclear existence,which are characterized by tiny production cross-sections and short half-lives.The isochronousmode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility project in China(HIAF-SRing)offers the capacity for such measurements.However,many factors limit the revolution time resolution of the isochronous mode of the large acceptance HIAF-SRing.Nonlinear field errors as well as fringe fields of the wide aperture dipoles and quadrupoles strongly excite the higher-order aberrations,which negatively affect the revolution time resolution.Moreover,the transverse emittance of the beam is inversely proportional to the revolution time resolution.Their influence is investigated here,and a possible correction scheme with sextupoles and octupoles is shown.With higher-order corrections,a mass resolution of R(FWHM)=1×10^(6),corresponding to a relative revolution time ofσ(T)/T~4.9×10^(-7),is with the isochronous settingγt=1.43 within the momentum acceptance of±0.2%.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12341501 and 11905074)。
文摘Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.
基金supported by Hefei Advanced Light Facility R&D project and the National Natural Science Foundation of China (No.11775216)
文摘The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory(NSRL)is a diffraction-limited storage ring(DLSR),which plans to use a full energy linac as the injector.To ensure injection efficiency,the injection beam needs to have low emittance.Therefore,a photocathode radio frequency(RF)gun was developed in the HALF R&D project.The gun is designed to deliver high-quality electron bunches with a typically 0.5 nC charge and~4.5 MeV energy with low emittance.The initial system commission with an electron beam was completed at the end of 2020,and a stable 1.2–1.4 mm.mrad emittance with a bunch charge of 500 pC was demonstrated.In this paper,we report the experimental results and experience obtained during the commission,including the RF gun,drive laser system,and beam diagnostics.
基金the the National Nature Science Foundation of China(12105333,12135017,12121005,11975280,12205340,12322507,12305126,12305151)。
文摘The measurement of mass,or equivalently the binding energy,of exotic nuclei has reached the limits of nuclear existence,which are characterized by tiny production cross-sections and short half-lives.The isochronousmode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility project in China(HIAF-SRing)offers the capacity for such measurements.However,many factors limit the revolution time resolution of the isochronous mode of the large acceptance HIAF-SRing.Nonlinear field errors as well as fringe fields of the wide aperture dipoles and quadrupoles strongly excite the higher-order aberrations,which negatively affect the revolution time resolution.Moreover,the transverse emittance of the beam is inversely proportional to the revolution time resolution.Their influence is investigated here,and a possible correction scheme with sextupoles and octupoles is shown.With higher-order corrections,a mass resolution of R(FWHM)=1×10^(6),corresponding to a relative revolution time ofσ(T)/T~4.9×10^(-7),is with the isochronous settingγt=1.43 within the momentum acceptance of±0.2%.
