60 Matching Results

Search Results

Advanced search parameters have been applied.

The resistively matched transition for measuring the coupling impedance of RHIC devices

Description: A resistive match has been developed as part of the measurement setup to determine the longitudinal coupling impedance of RHIC devices. Even though various calibration techniques have been implemented the broadband resistive match provides a smooth transition from the 50 {Omega} impedance of the HP8753C Network Analyzer to the 188 {Omega} characteristic impedance of the setup and can allow for valid measurements with a simple through reference calibration. The match has been tested for accuracy using both a narrowband quarterwave cavity and a broadband prototype bellow. In both cases an analytical approximation could be used together with a computer model to check the measured results. The errors in the calibrated measurement method have been tested to be less than 10% for frequencies up to 2 GHz.
Date: August 1, 1994
Creator: Ratti, A.
Partner: UNT Libraries Government Documents Department

Bench measurements of coupling impedance of AGS Booster components

Description: Quantifying instability thresholds for modern synchrotrons and storage rings requires some knowledge of the accelerator's coupling impedance. To this end, the wire technique has been implemented to measure the longitudinal coupling impedance of AGS Booster devices. The techniques are being refined to allow measurement of RHIC devices at higher frequencies. All the measurements are performed using an HP 8753 Network Analyzer controlled via GPIB by a Macintosh computer. The computer provides an environment for automated data acquisition, data analysis, and report generation. Resistive matches between the 50{omega} analyzer cables and the 300{omega} pipe-and-wire structure allow the use of a simple response calibration in the measurement of S21 to 400MHz. Results from ferrite loaded rf cavities, position monitors and kickers are presented. 4 refs., 4 figs.
Date: January 1, 1991
Creator: Ratti, A. & Shea, T.J.
Partner: UNT Libraries Government Documents Department

Frequency spectrum generated by AGS Booster power swing, heavy ion cycle

Description: LILCO is studying the effects of the AGS Booster power swing on its power grid. The study is being conducted by GE systems Development and Engineering, Schenectady, New York. In notes, dates November 10, 1987, prepared for a GE-LILCO Progress Review Meeting, the author notes LILCO system resonances that are excited by the heavy ion cycle. The data used by GE for their study, is the power flow required for continuous operation of the Booster, namely a continuous 13MW Power swing and a period of one second. The data used by GE came from BNL reports, used to analyze the power line flicker generated by this pulsating load. It is a worse case study and does not represent the Booster cycle. The Booster must be synchronized with the AGS, which is operated with a period of 3 seconds, when accelerating heavy ions. Thus the Booster duty cycle is 1/3 with a peak power swing of 13MW. The time of one second used to cycle the Booster magnets is arbitrary and can be increased to a maximum of three seconds. The peak power swing and the power spectrum are modified by the Booster duty cycle and period. The spectrum is critical for the GE study of the LILCO grid.
Date: July 17, 1992
Creator: Meth, M. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Calculation of Booster power requirements and power line flicker for 1. 5 GeV proton operation

Description: The Booster power requirements and power line flicker has been previously calculated for the 1 GEV proton cycle. Since then the maximum proton energy has been increased to 1.5 GEV, and the cycle period increased from 100 to 133 millisec. the design manual lists the peak magnet current as 2220A (previous value of 1672A). The maximum stored energy is increased by a factor of 1.763 and the power swing is increased by a factor of 1.32; increasing the flicker approximately by this factor. The required magnet voltage has been calculated and is given for the dipole and quadrupole strings. The total power at the AC bus bar isgiven. To calculate the reactive power, the dipole excitation is assumed to consist of 5--1000 volt supplies in series and sequentially switched. The quadrupole supply consist of 5--175 volt supplies in series and sequentially switched.
Date: July 17, 1992
Creator: Meth, A. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Calculation of Booster power requirements and power line flicker for 1.5 GeV proton operation

Description: The Booster power requirements and power line flicker has been previously calculated for the 1 GEV proton cycle. Since then the maximum proton energy has been increased to 1.5 GEV, and the cycle period increased from 100 to 133 millisec. the design manual lists the peak magnet current as 2220A (previous value of 1672A). The maximum stored energy is increased by a factor of 1.763 and the power swing is increased by a factor of 1.32; increasing the flicker approximately by this factor. The required magnet voltage has been calculated and is given for the dipole and quadrupole strings. The total power at the AC bus bar isgiven. To calculate the reactive power, the dipole excitation is assumed to consist of 5--1000 volt supplies in series and sequentially switched. The quadrupole supply consist of 5--175 volt supplies in series and sequentially switched.
Date: July 17, 1992
Creator: Meth, A. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Frequency spectrum generated by AGS Booster power swing, heavy ion cycle

Description: LILCO is studying the effects of the AGS Booster power swing on its power grid. The study is being conducted by GE systems Development and Engineering, Schenectady, New York. In notes, dates November 10, 1987, prepared for a GE-LILCO Progress Review Meeting, the author notes LILCO system resonances that are excited by the heavy ion cycle. The data used by GE for their study, is the power flow required for continuous operation of the Booster, namely a continuous 13MW Power swing and a period of one second. The data used by GE came from BNL reports, used to analyze the power line flicker generated by this pulsating load. It is a worse case study and does not represent the Booster cycle. The Booster must be synchronized with the AGS, which is operated with a period of 3 seconds, when accelerating heavy ions. Thus the Booster duty cycle is 1/3 with a peak power swing of 13MW. The time of one second used to cycle the Booster magnets is arbitrary and can be increased to a maximum of three seconds. The peak power swing and the power spectrum are modified by the Booster duty cycle and period. The spectrum is critical for the GE study of the LILCO grid.
Date: July 17, 1992
Creator: Meth, M. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Equivalent circuit analysis of the RHIC injection kicker

Description: The RHIC injection kicker is built as a traveling wave structure in order to assure the required 95 nsec risetime in the deflection strength. The kicker is constructed from 14 cells, each 7.5 cm long, with alternating ferrite and high-permittivity dielectric sections. The cell structure permits an analysis of the electrical properties of the kicker using lumped L, C, and R circuit elements. Their values are obtained directly from impedance measurements of the full-length kicker, the inductance and shunt capacitance values by measuring the input impedance at 1 MHz with the output shorted and open, respectively. A lossy series resonance circuit in each cell is found to reproduce the measured input impedance of the terminated kicker up to {approximately}100 MHz. The validity of the equivalent circuit was confirmed by comparing the measured output current pulse shape time with that computed by the P-Spice program.
Date: July 1, 1997
Creator: Hahn, H. & Ratti, A.
Partner: UNT Libraries Government Documents Department

The coupling impedance of the RHIC injection kicker system

Description: In this paper, results from impedance measurements on the RHIC injection kickers are reported. The kicker is configured as a {open_quotes}C{close_quotes} cross section magnet with interleaved ferrite and high-permittivity dielectric sections to achieve a travelling wave structure. The impedance was measured using the wire method in which a resistive match provides a smooth transition from the network analyzer to the reference line in the set-up. Accurate results are obtained by interpreting the forward scattering coefficient via the log-formula. The four kickers with their ceramic beam tubes contribute a Z/n = 0.22 {Omega}/ring in the interesting frequency range from 0.1 to 1 GHz, and less above. At frequencies above {approximately}100 MHZ, the impedance is ferrite dominated and not affected by the kicker terminations. Below 100 MHz, the Blumlein pulser with the {approximately}75 m feeding cables is visible in the impedance but makes no significant contribution to the results. The measurements show that the kicker coupling impedance is tolerable without the need for impedance reducing measures.
Date: July 1, 1997
Creator: Hahn, H. & Ratti, A.
Partner: UNT Libraries Government Documents Department

The RHIC accelerating cavity prototype tuner

Description: The RHIC Accelerating System runs at 26.7 MHz and is required to have an operating range of 85 kHz during the acceleration cycle. Since it also must provide sufficient range to cover manufacturing errors and temperature variation, a requirement of 300 kHz has been specified. A mechanical approach acting on the cavity accelerating gap has been chosen for financial reasons over a ferrite approach. A prototype has been constructed and fully tested on the existing test cavity, using the tuning loop feedback circuitry developed for this task. Results from both the loop response and the power tests of the prototype indicate that this design will successfully meet the performance requirements for the RHIC Accelerating Cavity.
Date: May 1, 1995
Creator: Ratti, A.; Brennan, J.M.; Brodowski, J.; Onillon, E. & Rose, J.
Partner: UNT Libraries Government Documents Department

Longitudinal impedance of capacitive pick-up electrodes: Calculations and comparison with measurements

Description: In order to obtain high sensitivity over a broad frequency range, split cylinder capacitive pick-up electrodes have been adopted as the beam position monitors (BPMs) for the AGS booster. Numerical simulation and prototype measurements have been employed to find the coupling impedance of a BPM. The impedance was calculated using the MAFIA computer codes, and measurements were made using a coaxial wire. We found that the measured impedance depended strongly on external electronics, which could not be modeled using the computer code. Additionally, the calculated impedance is a function of beam velocity, which was not studied in the measurements. Only by using both could a reliable bound on the shunt impedance be obtained. We find that the longitudinal impedance of the BPMs is negligible for normal operating conditions in the booster.
Date: September 1, 1992
Creator: Blaskiewicz, M.; Luccio, A.; Ratti, A. & Shea, T. J.
Partner: UNT Libraries Government Documents Department

Longitudinal impedance of capacitive pick-up electrodes: Calculations and comparison with measurements

Description: In order to obtain high sensitivity over a broad frequency range, split cylinder capacitive pick-up electrodes have been adopted as the beam position monitors (BPMs) for the AGS booster. Numerical simulation and prototype measurements have been employed to find the coupling impedance of a BPM. The impedance was calculated using the MAFIA computer codes, and measurements were made using a coaxial wire. We found that the measured impedance depended strongly on external electronics, which could not be modeled using the computer code. Additionally, the calculated impedance is a function of beam velocity, which was not studied in the measurements. Only by using both could a reliable bound on the shunt impedance be obtained. We find that the longitudinal impedance of the BPMs is negligible for normal operating conditions in the booster.
Date: January 1, 1992
Creator: Blaskiewicz, M.; Luccio, A.; Ratti, A. & Shea, T. J.
Partner: UNT Libraries Government Documents Department

Conceptual design of the 26.7 MHz RF system for RHIC

Description: The 26.7 MHz (harmonic No. h=342) RF system will be used to capture the injected bunched beam from the AGS and accelerate it to a kinetic energy of up to 250 GeV for protons; 100 GeV/u for gold ions. All ions except protons cross transition, and are finally transferred to a storage RF system working at 196 MHz. Each RHIC ring will be provided with two single-ended capacitively loaded quarter-wave cavities; each of these can be dynamically tuned by 100 kHz to compensate for the change in speed of the beam, and can deliver at least 200 kV voltage. A 100 kW tetrode amplifier with local RF feedback is directly coupled to the cavity to minimize phase delay. Prototypes of cavity and amplifier have been built and first test results are presented.
Date: June 1, 1993
Creator: Rose, J.; Deng, D. P.; McKenzie-Wilson, R.; Pirkl, W. & Ratti, A.
Partner: UNT Libraries Government Documents Department

Workshop on the RHIC performance

Description: The most recent conceptual design manual for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven was published in May 1986 (BNL 51932). The purpose of this workshop was to review the design specifications in this RHIC reference manual, and to discuss in detail possible improvements in machine performance by addressing four main areas. These areas are beam-beam interactions, stochastic cooling, rf and bunch instabilities. The contents of this proceedings are as follows. Following an overview of the workshop, in which the motivation and goals are discussed in detail, transcripts of the first day talks are given. Many of these transcripts are copies of the original transparencies presented at the meeting. The following four sections contain contributed papers, that resulted from discussions at the workshop within each of the four working groups. In addition, there is a group summary for each of the four working groups at the beginning of each section. Finally, a list of participants is given.
Date: July 1, 1988
Creator: Khiari, F.; Milutinovic, J.; Ratti, A. & Rhoades-Brown, M.J. (eds.)
Partner: UNT Libraries Government Documents Department

Simulations of the LHC high luminosity monitors at beam energies from 3.5 TeV to 7.0 TeV

Description: We have constructed two pairs of fast ionization chambers (BRAN) for measurement and optimization of luminosity at IR1 and IR5 of the LHC. These devices are capable of monitoring the performance of the LHC at low luminosity 10{sup 28} cm{sup -2}s{sup -1} during beam commissioning all the way up to the expected full luminosity of 10{sup 34} cm{sup -2}s{sup -1} at 7.0 TeV. The ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. To predict and improve the understanding of the BRAN performance, we created a detailed FLUKA model of the detector and its surroundings. In this paper, we describe the model and the results of our simulations including the detector's estimated response to pp collisions at beam energies of 3.5, 5.0, and 7.0 TeV per beam. In addition, these simulations show the sensitivity of the BRAN to the crossing angle of the two LHC beams. It is shown that the BRAN sensitivity to the crossing angle is proportional to the measurement of crossing angle by the LHC beam position monitors.
Date: March 28, 2011
Creator: Matis, H.S.; Miyamoto, R.; Humphreys, P.; Ratti, A.; Turner, W.C. & Stiller, J.
Partner: UNT Libraries Government Documents Department

RHIC 28 MHZ ACCELERATING CAVITY SYSTEM.

Description: The 28 MHz accelerating system consists of a quarter wave cavity driven by an inductively coupled 100kW tetrode amplifer and 1kW solid state driver amplifer. 40dB of rf feedback closed around the cavity and amplifers reduces small perturbations within the loop by a factor of 100, and reduces the time required to shift the phase at transition by a factor of 10, limited by the saturation of the drive chain. The cavity is tuned over a 200kHz range by a mechanical tuner which varies the gap capacitance. Broadband HOM damping is provided by two orthogonal loop coupled high pass filters. Design parameters and commissioning results are presented.
Date: June 18, 2001
Creator: ROSE,J.; BRENNAN,J.M.; CAMPBELL,A.; KWIATKOWSKI,S.; RATTI,A. & PIRKL,W.
Partner: UNT Libraries Government Documents Department

Simulation of the LHC BRAN luminosity monitor for high luminosity interaction regions

Description: The BRAN (Beam RAte of Neutrals) detector monitors the collision rates in the high luminosity interaction regions of LHC (ATLAS and CMS). This Argon gas ionization detector measures the forward neutral particles from collisions at the interaction point. To predict and improve the understanding of the detector's performance, we produced a detailed model of the detector and its surroundings in Fluka. In this paper, we present the model and results of our simulations including the detectors estimated response to interactions for beam energies of 3.5, 5, and 7 TeV.
Date: May 23, 2010
Creator: Miyamoto, R.; Matis, H.; Ratti, A.; Stiller, J. & White, S.M.
Partner: UNT Libraries Government Documents Department

Rf systems for RHIC

Description: The RHIC rf systems must capture the injected beam, accelerate it through transition to top energy, shorten the bunches prior to rebucketing, and store the beam for 10 hours in the presence of strong intra-beam scattering. These different functions are met by three independent systems. An accelerating system at 26.7 Mhz (h = 342), a storage system at 196.1 MHz (h = 2508), and a wideband system for the damping of injection efforts.
Date: May 1, 1995
Creator: Rose, J.; Brodowski, J.; Connolly, R.; Deng, D.P.; Kwiatkowski, S.; Pirkl, W. et al.
Partner: UNT Libraries Government Documents Department

Design of the 26.7 MHz rf cavity for RHIC

Description: The accelerating system for RHIC operates at 26.7 MHz (h = 342) and must capture the injected beam, accelerate it to top energy, and shorten the bunches prior to rebucketing into the storage (h = 2508) system. These different functions set the design parameters of the cavity. The frequency of 26.7 MHz has been chosen in order to provide large enough buckets to capture the injected beam from the AGS and a large linear region for debunching during a bunch rotation at top energy. Provision of the large linear region also dictates the voltage requirement of 400 kV per cavity. The cavity must be tuned {approximately}90 kHz to compensate for the change in speed of the gold beam.
Date: May 1, 1995
Creator: Rose, J.; Brodowski, J.; Deng, D.P.; Kwiatkowski, S.; Pirkl, W. & Ratti, A.
Partner: UNT Libraries Government Documents Department