Crosstalk Effect in the LEReC Booster Cavity (original) (raw)

Correction of Crosstalk Effect in the LEReC Booster Cavity

2019

The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7e-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler (FPC), pickup coupler (PU) and higher order mode (HOM) coupler close to each other. The direct coupling between FPC and PU induced crosstalk effect in this cavity. This effect is simulated and measured, and it is further corrected using low level RF (LLRF) to meet the energy spread requirement.

Correction of crosstalk effect in the Low Energy RHIC electron Cooler Booster Cavity

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

The Low Energy Relativistic Heavy Ion Collider (RHIC) electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with rms dp/p less than 5e-4. The superconducting radiofrequency (SRF) Booster Cavity is the major accelerating component in LEReC. It is a 0.4 cell cavity operating at 2 K, providing a maximum energy gain of 2.2 MeV. It is modified from an experimental Energy Recovery Linac (ERL) photocathode gun, and thus has fundamental power couplers (FPCs), pickup (PU) couplers (field probes) and HOM coupler close to each other on the same side of the cavity. Direct capacitive coupling between the FPC and PU, called the crosstalk effect, combined with microphonic detuning, can induce closed loop voltage fluctuations that exceed the total energy spread requirement of LEReC. The crosstalk effect in this cavity is modelled, simulated, and measured, and A correction method is proposed and demonstrated to suppress the voltage fluctuation so that energy spread requirement can be met.

First Results from Commissioning of Low Energy RHIC Electron Cooler (LEReC)

2019

The brand new non-magnetized bunched beam electron cooler (LEReC) [1] has been built to provide luminosity improvement for Beam Energy Scan II (BES-II) physics program at the Relativistic Heavy Ion Collider (RHIC) BES-II [2]. The LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. This high-current high-power accelerator was successfully commissioned in period of March -September 2018. Beam quality suitable for cooling has been demonstrated. In this paper we discuss beam commissioning results and experience learned during commissioning.

Design and Measurement of the 1.4 GHz Cavity for LEReC Linac

2021

The Low Energy RHIC electron Cooler (LEReC) is the first electron cooler based on rf acceleration of electron bunches. To further improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, a normal conducting RF cavity at 1.4 GHz was designed and fabricated for the LINAC that will provide longer electron bunches for the LEReC. It is a single-cell cavity with an effective cavity length shorter than half of the 1.4 GHz wavelength. This cavity was fabricated and tested on-site at BNL to verify RF properties, i.e. the resonance frequency, FPC coupling strength, tuner system performance, and high power tests. In this paper, we report the RF test results for this cavity.

DEVELOPMENT OF A PROTOTYPE 15 MeV ELECTRON LINAC

epaper.kek.jp

A successful development of a 6 MeV electron radiotherapy machine at SAMEER, India was reported earlier. Now a 15 MeV electron linac prototype is designed, developed and tested at our site. We have measured a beam current of 80 mA at the X-ray target attached to the linac. Energy gained by electrons in a cavity chain of about 1.2 m length is measured to be more than 15 MeV using a 6 MW klystron power source. An RF window capable of handling 12kW average power is attached to the linac tube and it is cooled by water. The final linac parameters measured were at par with the designed values. A high voltage modulator and control console for the linac are designed and developed in house. This paper will describe key aspects of the design and development process of the complete system. Also future applications are planned like-dual energy dual mode linac for radiotherapy, cargo scanning system and compact Compton X-ray source using this technology is briefed in this paper.

HOM Consideration of 704 MHz and 2.1 GHz Cavities for LEReC Linac

2016

To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. The Linac of LEReC is designed to deliver 2 MV to 5 MV electron beam, with rms dp/p less than 5·10⁻⁴. The HOM in this Linac is carefully studied to ensure this specification.

Large linac-based electron cooling device

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167), 1998

The electron beam for electron cooling is traditionally obtained by direct electrostatic acceleration. But for the higher electron energies (above 5 MV), the difficulties in implementing sharply increase and set natural limits for such method in use.

Electron Beam Generation and Transport for the RHIC Electron Cooler

Proceedings of the 2005 Particle Accelerator Conference, 2005

An electron cooler, based on an Energy Recovery Linac (Em) is under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. This will be the first electron cooler operating at high energy with bunched beams. A better understanding of the cooling process and more accwate measurements of Intra Beam Scattering in RHIC have imposed increased requirements on the electron accelerator: Besides a doubling of the bunch charge to 20 nC, the strength of the cooling solenoid was increased five-fold to 5 Tesla. The magnetic field on the cathode should be increased to 500 Gauss to match the magnetization required in the cooling solenoid. This paper reports the measures taken to minimize the electron beam emittance in the cooling section.

Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac

2015

To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energey RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for bunch stretching and energy spread correction. In this paper we report the design of these two cavities.

State-of-the-art electron guns and injector designs for energy recovery linacs (ERL)

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006

A key technology issue of energy recovery linac (ERL) high-power free-electron laser (FEL) and fourth generation light sources is the demonstration of reliable, high-brightness, highpower injector operation. Ongoing programs that target up to 0.5 Ampere injector performance at emittance values consistent with the requirements of these applications, are described. There are three approaches that could deliver the specified performance. These are DC photocathode guns with superconducting RF (SRF) booster cryomodules, high-current normal-conducting RF (NCRF) photoinjectors that may also use SRF boosters, and SRF photocathode guns and boosters. The achieved performance at existing ERL facilities, the status of ongoing source development programs, and the proposed parameters of the injectors for planned ERL facilities are described and compared. As examples, we concentrate on three high-current injectors being developed by Advanced Energy Systems (AES) with collaborators at the Thomas Jefferson National Accelerator Facility (JLAB), Los Alamos (LANL) and Brookhaven (BNL) National Laboratories. PACS: 29.17.+w, 29.27.AC, 41.85.Ja, 85.60.Ha Radio Frequency (SRF), Energy Recovery Linac (ERL).