It has been shown that a transverse deflecting cavity (TDC)-based de-chirper can be made by altering the drift sections in a TDC-based chirper to form negative drifts. While five appropriately configured quadrupole magnets can implement such negative drifts, this approach is limited by spatial and experimental constraints. In this study, we investigate an alternative configuration that uses three quadrupole magnets to form a negative identity transport section between the TDCs instead of a negative drift. To assess the robustness of this proposed design, a computational study has been conducted on initial beam conditions to determine the operational limitations. This includes the effects of space charge and initial transverse beam conditions, such as beam size and divergence, on the resulting transverse emittance.

Compact RF structures in the sub-terahertz regime are promising for structure wakefield acceleration due to their ability in achieving high gradients in a reduced footprint. We report on the design, fabrication, and testing of a metallic corrugated waveguide operating at 110 GHz, tailored to the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The experiment utilized the emittance exchange (EEX) beamline at AWA for longitudinal bunch shaping in two configurations: (1) a single short drive bunch to study high decelerating gradients, and (2) a two-bunch scheme featuring a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield and achieve a high transformer ratio. We will present the experimental design and results, which show good agreement with simulation predictions.

Recently, we proposed a novel photoinjector that incorporates an emittance exchange (EEX) beamline. Previous studies demonstrated promising 4D emittance performance of an EEX-based injector, but the beam’s longitudinal emittance at the linac exit still limits the final transverse emittance downstream of the EEX stage. We performed a comprehensive scan of injector parameters—including gun phase, laser spot size and pulse length, and solenoid strengths—to (1) estimate the minimum achievable longitudinal emittance, (2) identify sources of emittance growth, and (3) explore mitigation strategies. Here, we present the status of this study. Simulations were carried out using General Particle Tracer (GPT) including space-charge effects.

We present start-to-end simulation study of the transport of a few pico-Coulomb, nanometer-emittance beam through an emittance exchange (EEX) beamline. EEX with nanometer-emittance beams has potential to enable research opportunities utilizing tunable and high quality attosecond bunches and nanometer-scale longitudinal bunch trains. To account future possibility of experimental demonstrations, the simulation implemented existing EEX beamline at Argonne Wakefield Accelerator (AWA) facility. Simulation was conducted using General Particle Tracer (GPT) code.

We report progress on the design of a Phase Diversity Electro-Optic Sampling (DEOS)-based longitudinal profile measurement system. The current design uses THz coherent transition radiation (CTR) to convey the bunch’s longitudinal information. A 1550nm fiber laser available at the Argonne Wakefield Accelerator facility will be used as the probe for electro-optic sampling. Specifically, we discuss pulse synchronization and probe beam transport, the design and optimization of the probe beam stretcher, and the design of the probe beam detection system.

Positive-Ion Injector at ATLAS accelerator facility can accelerate heavy ions and has three key subsystems -- an electron cyclotron resonance (ECR) ion source, a 12-MHz multi-stage beam bunching system, and a 12-MV superconducting linac accelerator. The first stage of the bunching system is a multi-harmonic buncher that operates at 12.125 MHz and creates a bunch train with a period of 82.5 ns at ~70% bunching efficiency. The remaining unbunched beam must be removed to avoid the production of undesirable ‘satellite’ bunches, which can quench the superconducting solenoids downstream during operation. In this paper, we present the design of a resonant sine-wave RF-structure that effectively removes the bunch ‘tails’ using a vertically deflecting kick. We also discuss the effects of the RF-Kicker on the beam quality, which was estimated by TRACK3D simulations.

We report progress on the design of a Phase Diversity Electro-Optic Sampling (DEOS)-based longitudinal profile measurement system. The current design uses THz coherent transition radiation (CTR) to convey the bunch’s longitudinal information. A 1550nm fiber laser available at the Argonne Wakefield Accelerator facility will be used as the probe for electro-optic sampling. Specifically, we discuss pulse synchronization and probe beam transport, the design and optimization of the probe beam stretcher, and the design of the probe beam detection system.

High-resolution diagnostic instruments for measuring particle beam profile and charge are essential for characterizing the improved performance of charged particle accelerators. Beam diagnostics based on synthetic single crystal diamond (SCD) exhibit superior radiation-hardness, chemical stability, fast saturated drift speed, and unparalleled thermal conductivity. At Los Alamos National Laboratory (LANL), the SCD sensor and the high-speed signal acquisition system have been developed for measuring intensity of individual bunches. At the Argonne Wakefield Accelerator, a 63 MeV electron beam with diameter of 5 mm and charge below 10 pC used to measure the beam halo at a radial distance of 12 mm from the beam center. This presentation will report on the detailed SCD design and electronics, halo monitoring at various charges, bunches, and distances, and plans for future testing at LANL.

The emittance exchange (EEX) beamline at the Argonne Wakefield Accelerator (AWA) is designed to transfer properties of an electron beam phase space between the transverse and longitudinal planes. Recently, it has been proposed this beamline could be used to convert a microscale transverse modulation created by a TEM grid into a microbunch train in the longitudinal plane. Such a technique would be useful for obtaining nano-scale microbunching that does not rely on the sensitive process of FEL gain. This new approach has been proposed to enable development of a compact free-electron laser at Arizona State, greatly reducing size and cost compared with existing short wavelength FELs. To perform an exploratory demonstration of this concept at AWA, this experiment requires low normalized emittance (~50 nm·rad), low charge (~1pC) electron bunches, and transverse diagnostics with high-resolution (1-3 microns) and high-light-collection to resolve the modulation on the electron beam. This report will give a progress update on preparing the necessary beams and diagnostics at AWA for an emittance exchange experiment that would produce 100s of nm scale microbunches.

The Argonne Wakefield Accelerator test facility is dedicated to research on advanced acceleration, beam manipulation, and beam production. With a focus primarily in the development and testing of high-gradient wakefield-accelerator structures, the drive beamline RF photoinjector is capable of delivering high charge (100s of nC) 65 MeV electron bunch trains. We present the planned upgrades to the drive photoinjector aimed at increasing both beam brightness and stability, and report on the current progress for the first phase of the upgrade and upcoming RF gun installation.

The mitigation of the effects of coherent synchrotron radiation (CSR) is a key challenge in generating high brightness beams. Shielding by parallel plates installed in the dipole magnet vacuum chambers shows promise, both in simulation and experiment at small shielding gap separations. In this work, we consider a beam traversing a chicane with larger cm-scale separations on each dipole, necessitating the combined use of longitudinal profile shaping and shielding to reduce emittance growth. We model the radiated CSR using a 3D integrated Green's function technique that accounts for the complete 6D phase space of the bunch along with image charges to model shielding. This method is used in conjunction with a genetic algorithm to optimize the longitudinal current profile. Our results indicate current profiles that differ to results derived without shielding and allow for effective mitigation of emittance growth at cm-scale gaps. We will present details of the simulation and optimization method along with future plans, including ongoing experiments at the Argonne Wakefield Accelerator as part of a collaboration that seeks to investigate the effects of CSR on beams.

We present preliminary analysis results from a recent experiment investigating CSR shielding effects on a beam propagating through a chicane compressor. The experiment was conducted at the Argonne Wakefield Accelerator (AWA) facility. Two identical doglegs with reversing quadrupoles—flip the beam—allow the beamline to function as a chicane. Shielding gaps of 1, 2 , and 3 cm were tested using manually adjustable plates inside the dipole magnet chambers. The longitudinal phase space was measured both upstream and downstream of the chicane. To compare CSR-dominated propagation with ignorable CSR case, a wide slit was also applied to cut the beam charge.

We present start-to-end simulation study of the transport of a few pico-Coulomb, nanometer-emittance beam through an emittance exchange (EEX) beamline. EEX with nanometer-emittance beams has potential to enable research opportunities utilizing tunable and high quality attosecond bunches and nanometer-scale longitudinal bunch trains. To account future possibility of experimental demonstrations, the simulation implemented existing EEX beamline at Argonne Wakefield Accelerator (AWA) facility. Simulation was conducted using General Particle Tracer (GPT) code.

We present a simulation study to support the planning of experimental demonstrations of transverse wiggler-based correlation control. While previous simulations confirmed the feasibility of this approach, they did not incorporate realistic field maps of the transverse wigglers. In addition, the impact of various jitter and error sources—key concerns for experimental implementation—has not been analyzed. In this study, wiggler fields are generated through magnetostatic simulations and incorporated into start-to-end particle tracking simulations. The phase space responses to different jitter and error sources are also evaluated.

It has been shown that a transverse deflecting cavity (TDC)-based de-chirper can be made by altering the drift sections in a TDC-based chirper to form negative drifts. While five appropriately configured quadrupole magnets can implement such negative drifts, this approach is limited by spatial and experimental constraints. In this study, we investigate an alternative configuration that uses three quadrupole magnets to form a negative identity transport section between the TDCs instead of a negative drift. To assess the robustness of this proposed design, a computational study has been conducted on initial beam conditions to determine the operational limitations. This includes the effects of space charge and initial transverse beam conditions, such as beam size and divergence, on the resulting transverse emittance.

Compact RF structures in the sub-terahertz regime are promising for structure wakefield acceleration due to their ability in achieving high gradients in a reduced footprint. We report on the design, fabrication, and testing of a metallic corrugated waveguide operating at 110 GHz, tailored to the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The experiment utilized the emittance exchange (EEX) beamline at AWA for longitudinal bunch shaping in two configurations: (1) a single short drive bunch to study high decelerating gradients, and (2) a two-bunch scheme featuring a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield and achieve a high transformer ratio. We will present the experimental design and results, which show good agreement with simulation predictions.

Positive-Ion Injector at ATLAS accelerator facility can accelerate heavy ions and has three key subsystems -- an electron cyclotron resonance (ECR) ion source, a 12-MHz multi-stage beam bunching system, and a 12-MV superconducting linac accelerator. The first stage of the bunching system is a multi-harmonic buncher that operates at 12.125 MHz and creates a bunch train with a period of 82.5 ns at ~70% bunching efficiency. The remaining unbunched beam must be removed to avoid the production of undesirable ‘satellite’ bunches, which can quench the superconducting solenoids downstream during operation. In this paper, we present the design of a resonant sine-wave RF-structure that effectively removes the bunch ‘tails’ using a vertically deflecting kick. We also discuss the effects of the RF-Kicker on the beam quality, which was estimated by TRACK3D simulations.

Recently, we proposed a novel photoinjector that incorporates an emittance exchange (EEX) beamline. Previous studies demonstrated promising 4D emittance performance of an EEX-based injector, but the beam’s longitudinal emittance at the linac exit still limits the final transverse emittance downstream of the EEX stage. We performed a comprehensive scan of injector parameters—including gun phase, laser spot size and pulse length, and solenoid strengths—to (1) estimate the minimum achievable longitudinal emittance, (2) identify sources of emittance growth, and (3) explore mitigation strategies. Here, we present the status of this study. Simulations were carried out using General Particle Tracer (GPT) including space-charge effects.

We present the current status of preparations for the experimental demonstration of GW power generation from THz-TBA. The presentation will cover the status of structure fabrication, RF power extraction and absolute power measurement, and THz drive beam preparation. Currently, 0.4 THz structures are being fabricated using two improved methods over previous fabrication techniques. RF power extraction will be achieved using an on-axis elliptical horn antenna and off-axis parabolic mirrors. The RF power will be detected with a bolometer and calibrated based on the total beam energy loss measured by a spectrometer. In recent machine studies, we successfully generated a high-charge bunch train (1 nC/bunch) compatible with 0.4 THz structure.

The Transverse Deflecting Cavity Based Chirper (TCBC) is a novel concept of imposing and removing a significant energy chirp of an ultra-relativistic electron beam. The TCBC method requires much less footprint, compared to the conventional chirping and dechirping method involving operating a linear accelerator off-crest. When the compressed bunch is very short, the dechirping has to rely on the wakefields. We present our updated design of the L-band traverse deflecting cavity (TDC) for demonstrating the TCBC concept at the Argonne Wakefield Accelerator (AWA) facility. Our TDC design update is based on the original design provided by Tsinghua University. The TDC design update focused on ensuring improved performance under more intense electromagnetic fields, reducing the peak pulsed temperature rise. The tuners of the TDC were meanwhile reworked to allow greater adjustability of the resonant frequency and of the electromagnetic field balance among the cells. We also report the tolerance study of the TDC. Two copies of the TDC with the updated design are currently under fabrication with Dymenso, LLC.

Wigglers are periodic arrays of magnets with myriad applications in accelerator physics. Generally though, they are only tunable by adjusting the gap between jaws. Here, we present a wiggler based on diametrically magnetized cylindrical magnets with independently adjustable angle. This allows the realization of arbitrary (bandwidth constrained) magnetic configurations. We illustrate its application to the recently proposed "transverse wiggler" concept for transverse phase space control.