Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.

High voltage (HV) generators are used in multiple industrial and scientific facilities. Recent publications have demonstrated that triggering industrial thyristors (relatively slow switching devices) in overvoltage mode, also called impact ionization mode, significantly enhances their dU/dt and dI/dt characteristics. This novel triggering methodology necessitates the application of substantial overvoltage between the thyristor’s anode and cathode, delivered with a swift slew rate exceeding 1 kV/ns. The adoption of compact pulse generators constructed from commercially available off-the-shelf components (COTS) opens up avenues for deploying this technology across various domains, including the implementation of high-speed kicker generators in particle accelerators. In our methodology, we employed commercially available high-voltage SiC MOSFETs along with a custom-designed fast gate driver. This driver was conceptualized based on the recent development of gate boosting techniques, featuring a driving voltage exceeding 600 V. The gate driver for these MOSFETs comprises three key components: a level-shifter with NMOS and PMOS transistors, a compact Marx generator with two avalanche transistors, and a GaN HEMT in a high input and low output impedance configuration. The proposed gate-boosting driver achieves a slew rate exceeding 1 kV/ns for the driving pulse. Furthermore, we demonstrate that with this driver, a $1.7$ kV rated SiC MOSFET can produce an output pulse of $1.45$ kV and a maximum slew rate of ≈$2.5$ kV/ns. This gate-boosting driver aims to minimize commutation times, achieves a slew rate of over 1 kV/ns, and handle higher loads, making it ideal for impact ionization triggering of industrial thyristors.

In high-energy particle accelerators, kicker magnets are essential for injecting and extracting particle beams using fast-pulsed magnetic fields. A key challenge in their design is minimizing beam coupling impedance to maintain beam stability and reduce beam induced power losses while preserving the fast rise and fall times of the magnetic pulse. This paper presents innovative principles and mechanical approaches for reducing beam impedance in several kicker magnets operating under vacuum across the CERN complex. Kicker magnets use ferrite or laminated steel as a magnetic yoke, which is susceptible to beam-induced heating. The proposed techniques aim to screen the yoke, provide a low impedance path for the beam image current, and eliminate cavities that could generate resonances. Simultaneously, the screen must allow the passage of fast pulsed magnetic fields. Techniques include the insertion of ceramic chambers holding screen conductors, serigraphy of conductive paint, or thin metallization by sputtering. Bridges can eliminate cavities between adjacent magnets or vacuum vessels. The performance of these design strategies is evaluated through a combination of high-frequency simulations, laboratory impedance measurements, magnetic field assessments, and temperature monitoring of kicker magnets after installation in accelerators. The results demonstrate significant improvements up to 60-fold decrease, which are discussed in detail. This work establishes a foundation for further innovations in kicker magnet design, with the potential to enhance existing systems and guide the development for future accelerators such as FCC-ee, with shorter bunches, where the impedance is even more important.

In CERN’s beam transfer lines, high-voltage generators have traditionally relied on thyratron switches; however, thyratrons present operational challenges and are also becoming increasingly hard to source. To address this issue, there is a growing interest in adopting compact pulse generators made from commercially available off-the-shelf (COTS) components. Recent research has demonstrated that thyristors designed for rectifier applications, which are not specifically designed for fast rise times, can be activated in overvoltage mode—also referred to as impact-ionization mode. These devices achieve substantial improvements in their dU/dt and dI/dt characteristics. This activation method involves applying a substantial overvoltage between the thyristor’s anode and cathode, along with a fast slew rate exceeding 1 kV/ns. The adoption of compact pulse generators built from COTS components opens up new opportunities for deploying this technology across multiple domains, including high-speed kicker generators in particle accelerators. In our methodology, we incorporated commercially available high-voltage components—SiC MOSFETs—that were triggered using a fast gate driver, which was custom-designed. The generated output pulse was then amplified and sharpened in a four-stage Marx generator composed of small, $1.2$ kV rated D2PAK thyristors. This configuration yielded an output pulse with an amplitude of 11 kV and a 10–90% dU/dt of $13.3$ kV/ns. The present study details the design of the Marx generator and the resulting pulses, along with the challenges faced in high-voltage measurements.