Purpose In order to make BEPC-II to run at a higher energy,the Institute of High Energy Physics undertook an upgrading project.One of the important factors limiting the energy boost is the power and performance of the...Purpose In order to make BEPC-II to run at a higher energy,the Institute of High Energy Physics undertook an upgrading project.One of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies;therefore,these four magnet power supplies are developed for the BEPC-II upgrading.Methods The power supplies adopt topologies of thyristor rectifiers to realize a high-power output.In the control unit of each power supply,a digital current closed loop is adopted,and the key components in the feedback loop are thermostatically controlled.In order to improve the performances of the power supplies,analog voltage regulators are added to the inner control loops.Results These four power supplies have been tested and have already been officially used in BEPC-II,and their powers have reached the requirements of the upgrading.The test results of the current stability are described and shown in this paper,which testifies that the stabilities meet the design parameters.Conclusions A digital control is applied to each SCR rectifier control.The performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops,which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.展开更多
When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced ...When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.展开更多
The existing linear coupling theory and representation method are introduced briefly. The socalled local and global coupling is discussed in more detail. The vertical orbit distortion excited by a horizontal corrector...The existing linear coupling theory and representation method are introduced briefly. The socalled local and global coupling is discussed in more detail. The vertical orbit distortion excited by a horizontal corrector is represented with the coupling parameters at the corrector and the observation point. The formula is used to measure the coupling in BEPC II. In order to correct the coupling, vertical correctors are used to change the vertical orbit through sextupoles by a least square method. We also introduce and review other frequently used coupling measurement/tuning methods used in our machine.展开更多
In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonli...In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC II. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.展开更多
文摘Purpose In order to make BEPC-II to run at a higher energy,the Institute of High Energy Physics undertook an upgrading project.One of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies;therefore,these four magnet power supplies are developed for the BEPC-II upgrading.Methods The power supplies adopt topologies of thyristor rectifiers to realize a high-power output.In the control unit of each power supply,a digital current closed loop is adopted,and the key components in the feedback loop are thermostatically controlled.In order to improve the performances of the power supplies,analog voltage regulators are added to the inner control loops.Results These four power supplies have been tested and have already been officially used in BEPC-II,and their powers have reached the requirements of the upgrading.The test results of the current stability are described and shown in this paper,which testifies that the stabilities meet the design parameters.Conclusions A digital control is applied to each SCR rectifier control.The performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops,which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.
基金supported by the Beijing Electron Positron Collider Upgrade Project Funding Issues
文摘When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.
基金Supported by National Natural Science Foundation of China(10805051,10725525)
文摘The existing linear coupling theory and representation method are introduced briefly. The socalled local and global coupling is discussed in more detail. The vertical orbit distortion excited by a horizontal corrector is represented with the coupling parameters at the corrector and the observation point. The formula is used to measure the coupling in BEPC II. In order to correct the coupling, vertical correctors are used to change the vertical orbit through sextupoles by a least square method. We also introduce and review other frequently used coupling measurement/tuning methods used in our machine.
文摘In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC II. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.
