The Integrable Optics Test Accelerator (IOTA) is a storage ring for advanced beam physics research currently being built and commissioned at Fermilab. It will operate with protons and electrons using injectors with momenta of 70 and 150 MeV/c, respectively. The research program includes the study of nonlinear focusing integrable optical beam lattices based on special magnets and electron lenses, beam dynamics of space-charge effects and their compensation, optical stochastic cooling, and several other experiments. In this article, we present the design and main parameters of the facility, outline progress to date and provide the timeline of the construction, commissioning and research. The physical principles, design, and hardware implementation plans for the major IOTA experiments are also discussed.

https://iopscience.iop.org/article/10.1088/1748-0221/12/03/T03002/pdf

IOTA (Integrable Optics Test Accelerator): Facility and Experimental Beam Physics Program

In this paper, we describe the key features of the recently completed technical design for the International Linear Collider (ILC), a 200–500 GeV linear electron–positron collider (expandable to 1 TeV) that is based on 1.3 GHz superconducting radio-frequency (SCRF) technology. The machine parameters and detector characteristics have been chosen to complement the Large Hadron Collider physics, including the discovery of the Higgs boson, and to further exploit this new particle physics energy frontier with a precision instrument. The linear collider design is the result of nearly 20 years of R&D, resulting in a mature conceptual design for the ILC project that reflects an international consensus. We summarize the physics goals and capability of the ILC, the enabling R&D and resulting accelerator design, as well as the concepts for two complementary detectors. The ILC is technically ready to be proposed and built as a next generation lepton collider, perhaps to be built in stages beginning as a Higgs factory.

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The International Linear Collider

The LCLS-II is an upgrade of the Linac Coherent Light Source (LCLS) X-ray FEL based on a 4 GeV superconducting RF linac. The LCLS-II is designed to produce hundreds of watts of X-rays from 200 eV up to 5 keV. The linac uses 1.3 GHz 9-cell cavities processed using the N2-doping technique, and will be the first large-scale CW SCRF linac with a Q of roughly 3 x 10 at a gradient of 16 MV/m. The injector, which will be commissioned in spring 2018, is based on the normal-conducting CW RF APEX gun developed at LBNL. The LCLS-II will have two undulators: The soft X-ray undulator is a 39 mm period hybrid PM with an adjustable vertical gap to cover the range from 200 eV to 1.5 keV, and the hard X-ray undulator is a novel adjustable horizontal gap hybrid PM undulator with 26 mm period to generate vertically polarized X-rays from 1 to 5 keV. The talk will review the performance goals as well as some notable aspects of hardware fabrication. INITIATION, COST & SCHEDULE The Linac Coherent Light Source (LCLS) produced first X-rays in 2009, and quickly proved to be an effective research tool [1]. In July 2013, the Department of Energy Office of Science (DOE-SC) received a report [2] from its Basic Energy Sciences Advisory Committee recommending the construction of an X-ray FEL user facility with pulse repetition rate up to 1 MHz, beyond the capabilities of the 120 Hz SLAC linac. A collaboration of physicists and engineers from US accelerator laboratories (ANL, Cornell University, FNAL, JLAB, LBNL and SLAC) met for the first time in October 2013 to plan the construction of a free-electron laser employing a superconducting linac at SLAC. DOE-SC approved the conceptual design [3] of LCLS-II in August 2014. Construction began in March 2016, with the goal of completing the project no later than June 2022. The project budget is $1,045M, inclusive of materials, labor, civil construction and commissioning.

The LCLS-II: A High Power Upgrade to the LCLS

This article attempts to give a historical account and review of technological developments and innovations in radio frequency (RF) systems for particle accelerators. The evolution from electrostatic field to the use of RF voltage suggested by R. Wideroe made it possible to overcome the shortcomings of electrostatic accelerators, which limited the maximum achievable electric field due to voltage breakdown. After an introduction, we will provide reviews of technological developments of RF systems for particle accelerators.

History and Technology Developments of Radio Frequency (RF) Systems for Particle Accelerators

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices ie magnetrons The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs compared to current RF power system technology An operating CW system at 245 GHz has been experimentally developed Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load Amplitude dynamic range of 30 dB, amplitude stability of 03% rms, and phase stability of 026 degrees rms has been demonstrated

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Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.

https://iopscience.iop.org/article/10.1088/1748-0221/10/03/P03007/pdf

A 1.7 GHz waveguide Schottky detector system has been designed and built for each of the Fermilab Tevatron and recycler accelerators. The waveguide detector is designed to measure the betatron sideband and longitudinal Schottky signals of the accelerators at a frequency high enough to avoid coherent effects. Two detectors are used for each machine, one for horizontal and one for vertical betatron signals. Each detector is bi-directional providing both proton and antiproton signals. This paper describes the details of the waveguide design and construction as well as the design of the electronic system of the detector. Sensitivity calculations and bandwidth models are included. The electronic system utilizes down conversion to frequencies less than 10 MHz, so that the signals may be analyzed by standard instrumentation, such as a vector signal analyzer. The electronic system includes electronic gates to measure single or multiple bunches of protons or antiprotons with the RF as a source for tracking up and down energy ramps. The electronic system also includes a continuous beam emittance monitor

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A 1.7 GHz waveguide schottky detector system

The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW superconducting (SCRF) linac. The SCRF linac consists of 35 ILC style cryomodules (eight cavities each) for a total of 280 cavities. Expected cavity gradients are 16 MV/m with a loaded QL of ~ 4x107. The RF system will have 3.8 kW solid state amplifiers driving single cavities. To ensure optimum field stability a single source single cavity control system has been chosen. It consists of a precision four channel cavity receiver and RF stations (Forward, Reflected and Drive signals). In order to regulate the resonant frequency variations of the cavities due to He pressure, the tuning of each cavity is controlled by a Piezo actuator and a slow stepper motor. In addition the system (LLRF-amplifier-cavity) is being modeled and cavity microphonic testing has started. This paper describes the LLRF system under consideration, including recent modeling and cavity tests.

https://inspirehep.net/files/7061c63e01ca718db637f18f5f0cac45

Ed Cullerton

Papers

Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron

Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron

A 1.7 GHz waveguide schottky detector system

The LCLS-II LLRF System

PIP-II Injector Test Warm Front End: Commissioning Update