114890180
Improvement of Output Current Characteristics for Bira MCOR30 Correction Magnet Power Supply
The correction magnet power supplies installed at the Taiwan light source (TLS) are Bira Systems MCRO 30 power modules, a full-bridge configuration power stage converting the unregulated DC bulk power into a bi-polar current source. The MCOR 30 is theoretically regulated under a very fine control method, with this control method the Bira MCOR 30 should overcome the zero crossover distortion of a standard H-Bridge PWM schemes is used and result in a low frequency noise signature on the output when the magnet current is close to zero. The PWM control circuitry embedded in MCOR 30 theoretically but not really fulfills the purpose what the MCOR 30 want to achieve. With a home-made PWM control circuitry installed into MCOR 30, the width of real pulses can smoothly drop to zero, the MCOR 30 could output current not only with a low frequency noise signature but also with much higher bandwidth of frequency response and much lower Total Harmonic Distortion no matter what output current is demanded. INTRODUCTION The bipolar corrector magnet power supplies used in National synchronous radiation research center are BiRa systems MCOR 30 power modules[1]. The MCOR 30 is a modular product, designed to achieve high switching efficiency and small size, the maximum output about ± 50V / ± 30A, the output current with about 100Hz bandwidth should improve the overall speed of the electron beam orbit feedback system. The PWM control IC of MCOR 30 is a UC3856, in theory this PWM control IC is zero-crossing distortion, but in fact it is not, that results nonlinear behavior in low current output. In this paper, the IC LM555 presents a linear saw-tooth wave and combines an OP-AMP circuit to complete the fullbridge PWM control. The MCOR 30 could output current not only with a low frequency noise signature but also with much higher bandwidth of frequency response and much lower Total Harmonic Distortion no matter what output current is demanded. THE STRUCTURE OF CORRECTOR MAGNET POWER CONVERTER The MCOR 30 regulates the DC output current by controlling the pulse width modulation of an H-Bridge power MOSFET. This corrector magnet power converter could be roughly divided into four functional sections: Power regulation and filtering, Error amplifier, offset circuit, PWM control, Fault diagnosis, protection, monitoring and high precision current feedback system, as figure 1 shows. MCOR 30 is a full-bridge converter as figure 1 shows. The corrector power supply regulates the DC output current by controlling the pulse width of a half bridge power N-MOSFET array. For positive output current, Q1 and Q4 switch turn on and input DC source will charge energy and linear increase current to output load. When Q1 turn off the output current decay thought the Q4 and d3 turn on. For negative current is same to the mode [2].
73599484
High efficiency linear power supply with a preregulator controlled by keeping constant R/sub DS/ of MOSFET
In Synchrotron Radiation Research Center (SRRC) more than ninety linear power supplies with 100 ppm long-term stability are served for correction magnets. To increase the well-known efficiency problem of linear power supply, inside a customer-made bipolar linear power supply a homemade pre-regulator circuitry is in series in front of power stage. By using constant V/sub DS/ controlled pre-regulator, the power consumption of linear power supply itself could be reduced and the efficiency changes with respect to the output power. On the other hand, with constant R/sub DS/ controlled pre-regulator, the efficiency is even higher and is the ratio of load resistance and R/sub DS/. Design and performance of the pre-regulator circuitry are demonstrated.
110332574
Precision current monitor system for the power supplies at SRRC
At SRRC, a precision output current monitoring system is installed to monitor the output performance of all the booster/storage ring power supplies. Accurate DC current transformers (DCCTs) are attached to the output terminal of every power supply system. Each transformer's gain/offset are carefully calibrated against a high precision current source and approximated using high-order polynomial curve fitting. The output of each DCCT is connected to a multi-channel data logger for realtime data collection, the collected data are calibrated using the interpolated DCCT gain/offset value. A PC station is set up to serve as host to store the current output for real-time monitoring. This monitoring system provides a precise real-time database for rapid fault diagnosing whenever there is malfunction of the beam operation.
55506316
The Design and Fabrication of the Kicker Power Supply for TPS Project
The preliminary test results of the kicker power supply for TPS (Taiwan Photon Source) project will be presented in this report. The achieved capability of this test unit demonstrates that it fulfills the design requirement of providing half-sine pulsed current of 2.5 kA (peak), 5.2 μs (base-width), with jitter < 1 ns (peak-to-peak). Both units of using thyratron and IGBT switches are built with the same requirements. The technical considerations of both units for this particular application will be discussed. INTRODUCTION The Taiwan Photon Source (TPS) under construction consists of a 150 MeV electron linac, a 3 GeV full energy booster, and a 3 GeV storage ring. The storage ring is planned to operate top-up at 400 mA. The top-up filling process will take place periodically within about every 100 seconds. In order to fulfill this requirement, the injection kickers will be triggered repeatedly at the same repetition rate. This proposed topup operation mode requires stringent performance of the 4 injection kickers for good stability on pulse amplitude and jitter, and in particular, pulse-shape matching among these 4 kickers. Test units of the kicker pulser have been built to examine their feasibility. Pulsers using both thyratron and IGBT switches have been tested. The results show that both units fulfill the pulser requirements on amplitude and jitter stability. The system configuration and the test results are briefly described in this report. PERFORMANCE REQUIREMENTS The circumference of the TPS storage ring is 518.4 m [1]. Beam injection will be taken place at a 10 m long straight section. The proposed injection scheme demand a 5.2 μs (base-width) half-sine pulse for the injection kickers in order to perform four-turn injection process [2]. The estimated parameters had been applied to examine and evaluate the feasibility of building pulse power supply for kicker in house. The design of the prototype kicker magnet requires the driving peak current to be 2.5 kA. The suggested stability goals of both pulse amplitude and jitter for the test unit are given as 0.5% and 2 ns, respectively. Since top-up mode will be implemented in the future for routine user operation, performance on high reliability and small long term drift of the test unit are required. The stability will be examined and analyzed for this purpose. The estimated parameters for evaluating kicker pulser test unit are given in Table 1. Table 1: Parameters for evaluating kicker pulser test unit straight section (m) 10 magnet length (m) 0.6
210986666
TPS FAST CORRECTOR MAGNET POWER CONVERTER
M With the increasing demand of the current output accuracy on the TPS(Taiwan Photon Source) project, the MCOR 30 correction power supplies used in current TLS ring are no longer sufficient to meet the TPS requirement. Therefore, power supply group develops a high-precision low output current corrector magnet power supply with a DCCT as an output current feedback component for the future TPS ring. During the research and development experiment phase, we found the DCCT is more possible damaged than the other components. The implementation of the fast corrector magnet power converter is with keeping the architecture of the highprecision low output current power supply, but the DCCT output current feedback component is replaced with a current sensing Shunt resistor. This paper will discuss the design methods of utilizing several different types current sensing Shunt resistor to reduce the cost of power supply and the probability of damage, and improve frequency response of power supply.[1]
55337938
DESIGN AND MODELING OF THE STEP DOWN PIEZO TRANSFORMER
The energy conversion and the step down voltage waveform of the piezo transformer are required to achieve optimal working condition of the resonant frequency. To meet this requirement, a reliable and precise instrument is needed to scan the resonant point of the piezo transformer such that its output power performance can meet the required specification. In this paper, the design and model of a new step down piezo transformer deployed in NSRRC is described. This step down piezo transformer is capable of delivering energy conversion with high efficiency performance, which is better than traditional transformer, and the voltage transfer ratio is correct. Using the simulation circuit model to develop driver circuit of it is also included in the design of this new step down transformer. It has been tested and proven to be working well in power conversion with excellent efficiency and reliability.
91176234
DESIGN AND FABRICATION OF A 5-CELL HIGH CURRENT SUPERCONDUCTING CAVITY
Superconducting Energy Recovery Linacs have various applications, such as hard X-ray, electron-ion colliders and electron cooler of ions. The key component for accelerating such high current beams is the superconducting radio frequency cavity. The design of a 1.3 GHz 5-cell high current superconducting cavity has been carried out under the cooperation between Peking University and Argonne National Laboratory. Radio frequency property and damping of the higher order modes of this cavity have been discussed and the final design is presented. Room temperature RF measurements are also described in the paper.
117464950
Study on the multi-pass, multi-bunch beam breakup for 9-cell TESLA cavities in ERL *
Generally, Energy Recovery Linac (ERL) needs special designed high current superconducting RF cavities. In this paper, the threshold current of BBU for compact ERL facilities with 9-cell Tesla type cavities are investigated. The results show that it is feasible to adopt 9-cell Tesla cavity for compact ERL test facilities with just a few cavities and beam current around tens mA.
118620211
Relativistic Correction to Color Octet J/psi Production at Hadron Colliders
The relativistic corrections to the color-octet $J/\psi$ hadroproduction at the Tevatron and LHC are calculated up to $\mathcal{O}(v^2)$ in nonrelativistic QCD factorization frame. The short distance coefficients are obtained by matching full QCD with NRQCD results for the partonic subprocess $g+g\to J/\psi ({}^1S_0^{[8]},{}^3S_1^{[8]}, {}^3P_J^{[8]})+g$, $q+\bar{q}\to J/\psi ({}^1S_0^{[8]},{}^3S_1^{[8]}, {}^3P_J^{[8]})+g$ and $g+q({\bar{q}})\to J/\psi ({}^1S_0^{[8]},{}^3S_1^{[8]}, {}^3P_J^{[8]})+q({\bar{q}})$. The short distance coefficient ratios of relativistic correction to leading order for color-octet states ${^1}S_{0}^{[8]}$, ${^3}S_{1}^{[8]}$, and ${^3}P_{J}^{[8]}$ at large $p_T$ are approximately -5/6, -11/6, and -31/30, respectively, for each subprocess, and it is 1/6 for color-singlet state ${^3}S_{1}^{[1]}$. If the higher order long distance matrix elements are estimated through velocity scaling rule with adopting $v^2=0.23$ and the lower order long distance matrix elements are fixed, the leading order cross sections of color-octet states are reduced by about a factor of $20\sim40%$ at large $p_T$ at both the Tevatron and the LHC. Comparing with QCD radiative corrections to color-octet states, relativistic correction is ignored along with $p_T$ increasing. Using long distance matrix elements extracted from the fit to $J/\psi$ production at the Tevatron, we can find the unpolarization cross sections of $J/\psi$ production at the LHC taking into account both QCD and relativistic corrections are changed by about $20\sim50%$ of that considering only QCD corrections. These results indicate that relativistic corrections may play an important role in $J/\psi$ production at the Tevatron and the LHC.
15778530
Search for excited charmonium states in e+ e- annihilation at s**(1/2) = 10.6-GeV
We suggest searching for excited charmonium states in e + e - annihilation via double charmonium production at √s = 10.6 GeV with B factories, based on a more complete leading order calculation including both QCD and QED contributions for various processes. In particular, for the C = + states, the x c0 (nP) (n = 2, 3) and η c (mS) (m = 3, 4) may have appreciable potentials to be observed, while for the C = - states, the η c h c production and especially the X c1 h c production might provide opportunities for observing the h c with higher statistics in the future. A brief discussion for the X(3940) observed in the double charmonium production is included.
124456966
The NLO Calculations of Heavy Quarkonium Production at B Factories
We calculated the next to leading order quantum chromodynamics corrections of J/ψ production at B factories. The next to leading order corrections are very important for heavy quarkonium production at B factories. The next to leading order cross sections can be compared with the B factories data. Some detail of the next to leading order calculations within the non-relativistic quantum chromodynamics factorization framework are given here.