The CXFEL project at ASU will produce coherent soft x-ray radiation at a university-scale facility. Unlike conventional XFELs, the CXFEL will use an optical undulator in addition to nanobunching the electron beam instead of a static magnetic undulator. This reduces the undulator period from cm-scale to micron scale and lowers the requirements on the electron beam energy. CXFEL’s overtaking geometry design reduces the effective undulator period to 7.86 μm to produce 1 keV photons. This is accomplished by crossing the laser and electron beam at a 30 degree overtaking angle, and using a tilted laser pulse front to maintain temporal overlap between the electron beam and laser pulse. The inverse Compton scattering interaction between a microbunched electron beam and an optical undulator falls out of the range of most accelerator codes. We employ MITHRA, a FEL full-wave FDTD solver software package which includes inverse Compton scattering to simulate the FEL lasing process. We have adapted the code to the CXFEL instrument design to simulate the radiation/electron beam interactions and report results of studies including scaling of key parameters.

The automation upgrade of the photoinjector for the Compact X-Ray Light Source (CXLS) at Arizona State University is described. As the accelerator vault of the CXLS is only 10 meters long, the photoinjector drive laser is located in an enclosure inside the vault. Since ionizing radiation is present in this room during operations, it necessitates remote control of all devices used to optimize the laser spot. This includes multiple shutters, Galil motors, picomotors, a mirror flipper, LEDs, and remote lens controllers. To actuate these devices, a GUI was created with the use of MATLAB AppDesigner which communicates with the hardware through EPICS (Experimental Physics and Industrial Control System). Challenges with this GUI are described, along with the team’s efforts to finalize the control software. After these upgrades, the photoinjector laser characteristics can be adjusted remotely during operation and changes to the drive laser’s position, shape, and intensity can be made without interrupting beam time.

The Compact X-ray Light Source (CXLS) requires the acceleration of electron bunches to relativistic energies, which collide with focused IR laser pulses to produce X-rays which are then transported to the experiment hutch. A class 4 UV laser is used at the photocathode to liberate the electrons that are generated via the photoelectric effect. During electron acceleration bremsstrahlung radiation (gamma and neutron) is generated through electron interactions with solid matter. In the experiment hutch the X-rays then interact with the sample under test in pump-probe configuration where the pump laser is another class 4 laser with a wide spectral range from deep UV to THz. Interlock systems have been designed and deployed to protect users of the facility from exposure to these ionizing and laser radiation hazards. We present the design architecture of CXLS interlock systems. In this description we make clear what systems are independent, and which are interdependent and what administrative override modes are made available and why. We also provide an overview of our monthly interlock system testing protocols and conclude with comments on overall system performance.

The CXFEL project at ASU will produce coherent soft x-ray radiation at a university-scale facility. Unlike conventional XFELs, the CXFEL will use an optical undulator in addition to nanobunching the electron beam instead of a static magnetic undulator. This reduces the undulator period from cm-scale to micron scale and lowers the requirements on the electron beam energy. CXFEL’s overtaking geometry design reduces the effective undulator period to 7.86 μm to produce 1 keV photons. This is accomplished by crossing the laser and electron beam at a 30 degree overtaking angle, and using a tilted laser pulse front to maintain temporal overlap between the electron beam and laser pulse. The inverse Compton scattering interaction between a microbunched electron beam and an optical undulator falls out of the range of most accelerator codes. We employ MITHRA, a FEL full-wave FDTD solver software package which includes inverse Compton scattering to simulate the FEL lasing process. We have adapted the code to the CXFEL instrument design to simulate the radiation/electron beam interactions and report results of studies including scaling of key parameters.

The CXFEL is designed to produce attosecond-femtosecond pulses of soft X-rays in the range 300-2500 eV using nanobunched electron beams and a very high power laser undulator. The project includes 5 X-ray endstations with applications in biology, quantum materials, and AMO science. The CXFEL Project overall includes both the CXFEL and the nonlasing hard X-ray CXLS that is described elsewhere in these proceedings. The CXFEL has recently completed a 3-year design phase and received NSF funding in March 2023 for construction over the next 5 years. Both CXFEL and CXLS instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.

The Compact X-ray Light Source (CXLS) is a compact source of femtosecond pulses of x-rays that is now commissioning in the hard x-ray energy range 4-20 keV. It collides the beams from recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency, and recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 200 mJ. These instruments are designed to drive a user program in time-resolved x-ray studies such as SAXS/WAXS, XES and XAS, femtosecond crystallography as well as imaging. The different technical systems also act as prototypes for the more advanced CXFEL discussed elsewhere in these proceedings. We present the performance of the CXLS technical components and initial x-ray results.

Single objective Bayesian optimization is used in the simulation of the compact X-ray light source (CXLS) at Arizona State University, an inverse Compton based X-ray source, to optimize the 6D electron distribution prior to final focusing at the interaction point. For inverse Compton X-ray sources, a small 6D emittance as well as a small pulse (both transversely and longitudinally) are essential for producing bright X-ray pulses. Using IMPACT-T on a 200 pC initial charge with an RF photoinjector operating in blow-out mode, we vary parameters, such as transverse laser diameter on the cathode, RF gun phase, solenoid strength, as well as linac amplitude and phase, to balance minimizing the 6D emittance and spatial profiles. We test objective functions that are combinations of beam parameters, such as energy spread before final focus, pulse duration, and normalized emittance.

The Inverse Compton Scattering Interaction Point (ICS-IP) vacuum chamber provides a UHV environment where the electron and IR laser beams are overlapped in space and time to generate hard X-rays between 4 and 20 keV. The chamber has over two dozen motorized stages that position YAG screens with ~10 nm precision utilizing the EPICS framework for instrumentation interface. Using agile programming methods, MATLAB GUIs were created to control all the motors inside the chamber. Each YAG screen has a linear array of holes ranging between 10 microns and 2 mm that are imaged by cameras mounted on top of the chamber. Programmable focus lenses and IR mirrors are positioned to focus the IR laser at the interaction point. An X-ray optic is mounted onto a six degree of freedom nano-positioner enabling capture and collimation of X-rays coming from the IP. The X-ray optic can also be extracted from the beam path to transport the freely diverging X-rays to the experiment hutch for imaging experiments. We present the systems integration of the chamber, diagnostics elements, and control software and comment on its performance during instrument commissioning.

The automation upgrade of the photoinjector for the Compact X-Ray Light Source (CXLS) at Arizona State University is described. As the accelerator vault of the CXLS is only 10 meters long, the photoinjector drive laser is located in an enclosure inside the vault. Since ionizing radiation is present in this room during operations, it necessitates remote control of all devices used to optimize the laser spot. This includes multiple shutters, Galil motors, picomotors, a mirror flipper, LEDs, and remote lens controllers. To actuate these devices, a GUI was created with the use of MATLAB AppDesigner which communicates with the hardware through EPICS (Experimental Physics and Industrial Control System). Challenges with this GUI are described, along with the team’s efforts to finalize the control software. After these upgrades, the photoinjector laser characteristics can be adjusted remotely during operation and changes to the drive laser’s position, shape, and intensity can be made without interrupting beam time.

The Compact X-ray Light Source (CXLS) requires the acceleration of electron bunches to relativistic energies, which collide with focused IR laser pulses to produce X-rays which are then transported to the experiment hutch. A class 4 UV laser is used at the photocathode to liberate the electrons that are generated via the photoelectric effect. During electron acceleration bremsstrahlung radiation (gamma and neutron) is generated through electron interactions with solid matter. In the experiment hutch the X-rays then interact with the sample under test in pump-probe configuration where the pump laser is another class 4 laser with a wide spectral range from deep UV to THz. Interlock systems have been designed and deployed to protect users of the facility from exposure to these ionizing and laser radiation hazards. We present the design architecture of CXLS interlock systems. In this description we make clear what systems are independent, and which are interdependent and what administrative override modes are made available and why. We also provide an overview of our monthly interlock system testing protocols and conclude with comments on overall system performance.

The Compact X-ray Free-Electron Laser Labs (CXFEL Labs) encompass facility infrastructure that supports the operation of two beamlines, the Compact X-ray Light Source (CXLS) beamline (6-10 keV, <500 fs X-ray pulses @ 1 kHz), and the Compact X ray Free-Electron Laser (CXFEL) beamline (0.25-2.5 keV, <10 fs X-ray pulses @ 1 kHz). We present an overview of the science instrumentation and its requirements for CXLS and CXFEL and how these physics requirements translate to engineering specifications that drive the facility design. The facility design includes many interdependent systems including: network; on-lab and off-lab data processing and storage; fast and slow controls; air and water systems; health and safety systems; power distribution; vibration isolation; electron, laser, and x-ray beam transport, for example. We articulate specific challenges associated with beam transport where sub-10-fs timing requirements exist across multiple rooms, and network requirements for large data flow from 1 kHz source in a compact footprint with reasonable cost. We conclude with an overview of implementation status for the CXLS and CXFEL beamlines.