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

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

Linear accelerators, like the Free-electron LASer in Hamburg (FLASH) or the European X-Ray Free Electron Laser (E-XFEL) take advantage of the digital Low Level Radio Frequency (LLRF) system to control the phase and amplitude of an electromagnetic field inside superconducting cavities. The real-time control LLRF system, processing data within a few microseconds, has to fulfil performance requirements and provide comprehensive monitoring and diagnostics. The AMC-based controller (DAMC-TCK7) board was developed as a general purpose high-performance low-latency data processing unit designed according to the PICMG MTCA.4 spec. The module provides the processing power, data memory, communication links, reference clock, trigger and interlock signals that are required in modern LLRF control systems. The module was originally designed as a cavity field stabilizing controller for standing-wave linear accelerators. However, the application of the board is much wider because it is a general purpose data processing module suitable for systems requiring low latency and high-speed digital signal processing. According to authors’ knowledge this is the first MTCA.4 module offering 12.5 Gbps links, unified Zone 3 connectivity and advanced Module Management Controller proposed by DESY. The DAMC-TCK7 card was used as a hardware template for the development of the other AMC modules of the XFEL accelerator’s LLRF system. This paper discusses the requirements for the digital real-time data processing module, presents the laboratory performance evaluation and verification in Cryo-Module Test Bench (CMTB) at DESY.

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High-speed data processing module for LLRF

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

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

The LCLS-II LLRF System

The field control of multiple superconducting RF cavities with a single Klystron, such as the proposed RF scheme for the ILC, requires high density (number of RF channels) signal processing hardware so that vector control may be implemented with minimum group delay. The MFC (Multichannel Field Control) module is a 33- channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs. A 32-bit, 400MHz floating point DSP provides additional computational and control capability for calibration and implementation of more complex control algorithms. Multiple high speed serial transceivers on the front panel and the backplane bus allow a flexible architecture for inter-module real time data exchanges. An interface CPLD supports the VXI bus protocol for communication to a SlotO CPU, with Ethernet connections for remote in system programming of the FPGA and DSP as well as data acquisition.

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Multichannel vector field control module for LLRF control of superconducting cavities

Fermilab has built a cryomodule comprised of eight 1.3 GHz superconducting RF cavities for use in its Advanced Superconducting Test Accelerator (ASTA) facility. This cryomodule (RFCA002) was intended to achieve the !" # $ l of demonstrating an average accelerating gradient of 31.5 MV/m, and is the first of its kind built in the United States. The module has been cooled down and operated without beam at ASTA in order to assess its performance. The results from these tests are presented here

Philip Varghese

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

The LCLS-II LLRF System

Multichannel vector field control module for LLRF control of superconducting cavities

Results from RF Tests of the First US-built High-gradient Superconducting Cryomodule