Engineering topics
Publications and source records attributed to Pinayev, Igor.
Electron-ion collider will employ transverse deflecting (crabbing) cavities to increase luminosity. There will be multiple cavities which will create localized crab bump in the interaction region. For proper compensation of the crossing angle each crab cavity should individually calibrated and phased.
The design of the electron-ion collider (EIC) at Brookhaven National Laboratory is well underway, aiming at a peak electron-proton luminosity of 10e+34 cm^-1·sec^-1. This high luminosity, the wide center-of-mass energy range from 29 to 141 GeV (e-p) and the high level of polarization require innovative solutions to maximize the performance of the machine, which makes the EIC one of the most challenging accelerator projects to date. The complexity of the EIC will be discussed, and the project status and plans will be presented.
Optical diagnostics is widely used for measurement of the electron beam parameters such as bunch length, beam size, and emittance. Using undulator radiation extends these measurements to the beam energy and energy spread. In this paper, we will study the applicability of synchrotron radiation for protons.
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will reuse most of the existing superconducting magnets from the RHIC storage ring. However, the existing stripline beam position monitors (BPM) used for RHIC will not be compatible with the planned EIC hadron beam parameters that include higher intensity, shorter bunches, and some operational scenarios with large radial offsets of the beam in the vacuum chamber. To address these challenges, the existing RHIC stripline BPMs will be shielded, and a new BPM design using button pick-ups and integrated in a new vacuum interconnect/bellows assembly that will be installed adjacent to the existing BPMs. A thermal analysis of the new arc BPM housing and button pick-up design has been conducted to assess the effects caused by beam induced resistive wall heating and signal propagation through the button pick-up cables for several operational scenarios. This report will describe the analysis results to quantify the heat transfer and temperature distribution that can be expected on the new HSR cryogenic arc BPM housings, button pick-ups, and cryo-signal cables.
The essence of the ERL operation implies that at least two beams (accelerated and decelerated) are co-propagating in the same vacuum vessel and each beam has its own trajectory. The existing beam position monitors measure only “average” trajectory but not that of an individual beam, unless the time separation between bunches is so large that one can resolve individual bunches. It was proposed to use phase information of the pick-up signal to extract information on the orbit “difference”. We are planning to conduct experiments at RHIC to test the proposed idea. The approach and experiment set-up are described in the paper.
Growing demand on the beam orbit stability requires higher loop gain inside the operational bandwidth. However, increasing the gain leads to the increase of the unity gain frequency and problems with systems stability due to the additional phase shifts caused by the trims (power supplies, eddy currents in vacuum chambers, etc.) and filtering of beam position data. Conventionally employed systems have 20 dB/decade slope near the unity gain providing 90 degrees phase shift which is sufficient for stability. Increase of the slope to 40 dB/decade by adding additional pole into the signal chain increases the phase shift to 180 degrees and makes system unstable. Utilizing one or more lag compensators allows to increase the gain while keeping phase margin acceptable. The paper provides more details on the proposed solution as well as simulations of how the transients will be modified.
Solenoids are frequently used for focusing low-energy beams. In this paper, we show how they can serve as multipurpose diagnostics tools to measure various beam parameters, including energy, emittance, the second moments of the transverse distribution, and the beam position and angle with respect to the solenoid’s axis. The energy measurement is based on rotation of the plane of the transverse motion, as opposed to generating dispersion with a dipole. Measurement of the beam trajectory with respect to the solenoid axis is done by analyzing the beam orbit downstream of the solenoid while varying its current. The second moments are calculated by analyzing the beam image on a profile monitor while accounting for the beam rotation caused by the solenoid. We describe in detail the corresponding procedures and the experimental results of these measurements.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The storage ring current monitor is expected to be utilized for the following functions: measurement of the current circulating in the storage ring; measurement of the beam lifetime; measurement of the injection efficiency; provide the level of the circulating current for the equipment protection system; provide amount of charge required for the next injection cycle in the top-up mode operation. The current will be monitored with a parametric current transformer (DCCT) integrated into the vacuum system of the storage ring. The electronic module will convert the current reading into the corresponding voltage which will be measured with a digital voltmeter (DVM). The digitized data will be processed by the control system.
Initial testing was performed by P. Cameron. Ten assemblies were tested for the electrical resistance, stray capacitance, trapped mode frequency, dimensional tests, voltage standing wave ratio (VSWR), pin insertion/withdrawal force, and vacuum leak check. After satisfactory results the production run started. The acceptance tests are described below.
Processors for the beam position monitors (BPMs) will be provided by BSA.
The NSLS-II storage ring will provide a light source with unprecedented brightness. To utilize fully ultra-low emittance of electron beam we need to keep orbit in the storage ring with high precision. This paper presents mathematical modeling of different geometries of beam position monitor buttons, including button diameter and horizontal separation of button centers. The results of modeling are used for the optimization of BPM sensitivity to beam displacement and estimation of signal levels.
Model, Skew Quadrupole Components, Vertical Dispersion, Skew Beam Response Matrix Elements, Control of Vertical Beam Size, and References are reported here.
Stability requirements High stability BPM will be used for stabilization of transverse position of the electron beam circulating in the storage ring. To provide required stability overall error in the beam position should not exceed 0.15 microns for the vertical plane and 2 microns in the horizontal plane. Assuming electronic noise of the BPM receivers 0.1 microns we can find that vertical position of the BPM should be stable within 0.1 microns, while allowable horizontal mechanical motion is defined by the required error. For the longitudinal position we assume that electron beam travels 1 milliradians angle with respect to the axis. In this case longitudinal motion will translate into the observed transverse position δx, y = α x,y δs and tolerances will be defined by the requirements vertical plane. For 0.01 microns error longitudinal displacement should not exceed 10 μm. These requirements are for r.m.s. motion over 8 hours time period (note that end station located at 25 m from the source will move by 1.5 microns r.m.s. due to the ground motion).
Modeling of orbit feedback with realistic parameters of elements (including 360 microseconds delay) showed feasibility of robust solution with good dynamic response.