ReBCO high-temperature superconducting (HTS) tape is critical for achieving the high magnetic fields needed in next-generation particle accelerators. Enhancing the mechanical performance of ReBCO tape increases its critical current by reducing internal stress, especially in the superconducting layer. A finite element study examined how copper layer properties affect stress in ReBCO conductor...
A novel structure-based wakefield accelerator is proposed. This accelerator uses the structure that simultaneously acts as a slow-wave medium stimulating Čerenkov radiation of electrons propagating the structure and suppresses the beam breakup instability. Examples of the structure are presented alongside of the calculations demonstrating the feasibility of this novel approach.
Superconducting radio frequency (SRF) cavities based on Nb$_3$Sn superconductor can exceed the performance of conventional Niobium SRF cavities and would open many new industrial applications for small scale accelerators. The material quality-especially the surface non-homogeneity and microstructural defects, is the crucial challenge to realize the full potential of Nb$_3$Sn SRF cavities. In...
To address the intrinsic dynamic aperture (DA) limitations of fourth-generation diffraction-limited synchrotron light source, we investigate a novel injection scheme utilizing multiple nonlinear kickers (NLKs) with optimized hardware design and phase advances in the storage ring (SR). Positioning the NLKs near the injection point reduces beam perturbation, while their on-axis zero field and...
The Fermilab Main Injector accelerating cavities have sparking issues when they are run at voltages higher than those required by the PIP-II project. This is a problem Fermilab is working on as planning begins for the next upgrade to the accelerator complex. One of the methods being used to address the issue is the development of a CST Microwave Studio simulation to accurately model the PIP-II...
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...
Our approach to the physics of vacuum arcs, which limits many technologies, has been to model rf breakdown in vacuum in four stages (trigger, ionization, evolution and damage), then generalize the model, filling in details with data from other fields, such as accelerator design, power transmission grid limits, large tokamaks, sample failures in atom probe tomography and thin film sputter...
In particle accelerator facilities, cooling-water pumps play a critical role in removing substantial amounts (in megawatts) of waste heat from numerous high-power accelerator components (e.g., magnets, radio frequency structures, power supplies) and beamline components*. Despite their role in daily operations, inspecting hundreds of water pumps is labor-intensive and performed only...
Due to the spatial constraints of the small-aperture magnets in the storage ring arc zone of the High Energy Photon Source (HEPS), where the magnetic pole gap is 26 mm and the vacuum chamber outer diameter is 24 mm, it is necessary to bake the vacuum chamber within a unilateral clearance of only 1 mm for the vacuum chamber degassing and NEG-coated film activation. This work introduces the...
This work reports the first application of centrifugal barrel polishing (CBP) to a 650 MHz single-cell niobium superconducting radio frequency cavity. The CBP was performed using a newly installed large tumbler designed to accommodate four large-sized 650 MHz multi-cell cavities. The CBP process was applied to reset the cavity’s internal rough surface prior to electropolishing (EP). The study...
Nb$_3$Sn demonstrates steady advancements nowadays offering reduced power cost in superconducting radio-frequency cavities due to its high critical temperature, quality factor, and achieved accelerating gradient. However, theoretical estimates of its radio-frequency parameters have not been achieved due to several potentially limiting mechanisms: tin spots, patchy regions, defects, thermal...
Nb₃Sn, with its superior superconducting critical temperature (Tc ~18.3 K) and superheating field (Hsh ~400 mT), is considered a promising material for superconducting radiofrequency (SRF) cavities, offering enhanced cryogenic performance compared to bulk niobium cavities. A Nb₃Sn coating technique has been developed for Nb SRF cavities using co-sputtering of Nb-Sn composite target in a DC...
In recent years, plasma accelerators have advanced significantly toward producing beams suitable for colliders, aiming to replace conventional MV/m RF fields with GV/m fields of nonlinear plasma waves. Realizing a plasma-based collider requires electron bunches with high charge (hundreds of pC), low normalized emittance (~100 nm), and energy spread below 1%. Minimizing energy spread during...
We present a compact electron buncher that uses a permanent magnet setup for beam focusing. The buncher modulates the input direct-current beam into 5.7-GHz bunch train. The buncher consists of two radiofrequency (RF) cavities. Immediately downstream of each RF cavity, there is an electrostatic potential depression (EPD) section. An EPD section in an electrically insulated beam pipe biased...
The HTS conductor hysteresis dominates magnet cable power loss but is independent of the magnetic field ramping rate. This makes the HTS conductor suitable to power the rapid-cycling accelerator magnet. We present a possible application of the HTS rapid-cycling magnet as outlined in [1,2] for the staged muon acceleration including the front-end Recirculating Linear Accelerator and the...
Ultra nanocrystalline diamond (UNCD) is a promising material for field emitters because of its mechanical and chemical stability, high thermal conductivity, and low electrical resistivity. We proposed to demonstrate fabrication of a special shape field emitter array to produce a sheet electron beam for high frequency vacuum tubes. At Los Alamos, we established a Field Emitter Array Test Stand...
RF breakdown is the major limitation to achieving higher accelerating gradients. Recent experimental evidence shows that this limitation can be mitigated by reducing the RF pulse length to a few nanoseconds. One key challenge in designing an accelerator operating in the short-pulse regime is achieving the required short filling time. In this work, we designed a novel waveguide power splitter...
High-brightness, ultra-high peak current electron beams are of great interest for a range of applications, including high-energy colliders, strong field quantum electrodynamics, and laboratory astrophysics. However, the task of compressing electron beams to attosecond pulse durations and mega-amp peak currents while maintaining beam quality continues to pose a significant challenge. We...
RF loads are critical components in any high-power rf system. There are two types of commonly used rf loads in multi-megawatt systems: water loads and dry loads. Water loads have a ceramic window separating vacuum from the water. Use of water loads in large scale rf systems is risky because of the possibility of water leaking into vacuum. At SLAC multi-megawatt dry loads were developed and...
Los Alamos Neutron Science Center has a project to investigate the feasibility for a replacement radio-frequency (RF) amplifier that is not reliant on vacuum electron tubes, a similar footprint, and equivalent RF functionality. Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMT) will be used in combined configuration. To maintain existing operational...
In support of the development of a conduction-cooled 915MHz superconducting radio frequency (SRF) cryomodule, this study highlights the design of a shipping fixture for transporting the hermetic assembly 4500 km from Jefferson Lab to General Atomics in San Diego, California. The hermetic assembly consists of a 2-cell 915 MHz SRF cavity, a coaxial fundamental power coupler and warm-to-cold...
Optical stochastic cooling (OSC) is a cutting-edge beam cooling technology to reduce, control the 3 dimensional spread and the motion of particle beams. It has recently been successfully, experimentally, demonstrated in Fermilab's IOTA storage ring, marking a major step forward in beam cooling. OSC has the potential to significantly improve both the performance and flexibility as a beam...
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...
A novel deuteron cyclotron auto-resonance accelerator (dCARA) is described here. It is predicted to produce a 40-MeV, 125 mA CW deuteron beam, with notable features including continuous acceleration without bunching for good beam stability, high efficiency, wide beam aperture, and an exceptionally short length of 1.6 meters. Such an accelerated beam can be used to produce the intense neutron...
Structure Wakefield Acceleration (SWFA) powered by -short RF pulses (~10 ns) generated by Two-Beam Acceleration (TBA) at the Argonne Wakefield Accelerator (AWA) has demonstrated effective suppression of RF breakdowns and achieved gradients exceeding 400 MV/m at X-band (11.7 GHz) frequencies. To fully exploit the benefits of this short RF pulse operation, an accelerating structure must...
Compact SRF industrial linacs can provide unique parameters of the beam (>1 MW and >1-10 MeV) hardly achievable by normal conducting linacs within limited space. SRF technology was prohibitively expensive until the development of conduction cooling which opened the way for compact stand alone SRF systems suitable for industrial and research applications. Limited cooling capacity puts strict...
This paper focuses on the R&D performed for the development of permanent magnets-based dipoles-quadrupoles combined function magnets (PMQs) for the future NSLSII upgrade “complex bend” lattice (CB). This new lattice uses PMQs that provide both bending (dipole) and strong focusing (quadrupole) magnetic field on the electron beam. The permanent magnet (PM) technology is suitable for the high...
We have developed a new SLED-type RF pulse compressor for powering ultra-high gradient X-band photoinjectors with pulse lengths shorter than 10 ns. Klystrons capable of generating these short pulses at multi-MW levels are non-existent. However, RF pulse compression is an alternative technique used to increase klystron output peak power at the cost of pulse length. Over the years, we have...
We present latest developments to Lume-ACE3P. Lume-ACE3P is a Python wrapper streamlining workflow for ACE3P, a suite of finite element solvers for electromagnetic fields in complex geometries. We have expanded Lume-ACE3P to allow users to perform parameter sweeps over all input parameters, including mesh file, geometry properties like type of material and material conductivity, and finite...
A normal conducting, high power, high efficiency copper linear accelerator prototype is being developed for industrial applications. The system will be powered by low-cost high-efficiency magnetron RF sources and will use a gridded thermionic cathode electron gun. Leveraging the significant accelerator expertise at JLab and industry partners, these technologies will be combined to deliver...
By using TELENE® resin as superconducting magnet impregnation material, training and magnet retraining after a thermal cycle were nearly eliminated in Nb3Sn undulators. This allows reducing operation margins in light sources, and increasing the on-axis magnetic field, thereby expanding energy range and brightness intensity. TELENE is Co-60 gamma radiation resistant up to 7-8 MGy, and therefore...
In this contribution we report on the experimental generation of high energy (10 GeV), ultra-short (fs-duration), ultra-high current (∼ 0.1 MA), petawatt peak power electron beams at the FACET-II National User Facility at SLAC National Accelerator Laboratory. These extreme beams enable the exploration of a new frontier of high intensity beam-light and beam-matter interactions broadly relevant...
To compete with conventional accelerators, collider and light source applications based on plasma wakefield acceleration need to be able to handle 10s of Joules of energy transfer between the drive beam, plasma, and witness beam at repetition rates exceeding 100 Hz. Scaling up to these parameters is challenging due to the large amount of heat deposited in the plasma source. To begin...
The following work will detail the development and implementation of a system which will measure the voltage and current from two points on a high-voltage switch called a thyratron and automatically manipulate two variable transformers controlling these values. Each of the extraction kickers at LANSCE (SRFK71 & SRFK81) uses a thyratron to trigger their respective pulses. The thyratrons have...
Structure-based wakefield accelerators (SWFA) have been identified as a candidate technology for future applications ranging from free electron lasers to colliders. However, achieving the desired beam energy and quality requires meter-scale structures with tight tolerances, placing constraints on structure and beam characteristics to minimize emittance growth and combat transverse...
In this work we outline the final design and initial measurement lessons for the holders and measuring apparatus of the permanent magnet resiliency experiment which is a part of the FFA@CEBAF proposed upgrade. The experiment will expose permanent magnets to the radiation environment of CEBAF. Due to safety regulations we need to measure the magnets in the tunnel without bringing them out, so...
Fermilab is advancing the development of a compact, high-power electron beam accelerator using superconducting radio frequency (SRF) technology as a non-radioactive alternative to traditional radiological sources. The current design targets continuous-wave (CW) operation at 1.6 MeV and 20 kW. To ensure suitability for industrial environments, the system is being designed for cryogen-free...
Fermilab’s Main Injector Accelerator has used shell & tube heat exchangers to cool various beamline components since its construction in the late 1990s. Many of the heat exchangers still around today are original to the machine. Untreated pond water has been used to exchange heat with the Low Conductivity Water. Throughout the lifetime of Fermilab’s heat exchangers, they have undergone...
As part of the Advanced Photon Source Upgrade (APS-U), two high-power DC supplies for the L-Bend M1 and M2 magnets were installed. During the APS-U commissioning, a 1 Hz ripple was detected in the output currents of the M1/M2 and slow corrector supplies, leading to 1 Hz beam motion. This low-frequency harmonic originated from the booster ramping supply operating at 1 Hz, causing periodic grid...
As beam sizes get smaller at the collision point, the environment vibrations and their amplification through the accelerators supporting structures need more careful considerations. Indeed these mechanical disturbances can produce a beam orbit jitter that is detrimental to a collider operation, through loss of luminosity or increased beam-beam effects.
In preparation for EIC, measurements of...
An advanced charge selector is currently under development at the Facility for Rare Isotope Beams (FRIB) to intercept unwanted charge states of stripped heavy ion beams. Rotating graphite wheels are employed to absorb beams with a power up to 5 kW and a size as small as an rms width of 0.7 mm × 1.25 mm.
The implantation of beam ions and accumulated radiation damage affect the material...
Recent efforts at SLAC aim at developing high-power accelerators powered by compact, high-efficiency rf sources such as klystrons and Inductive output tubes (IOT). In particular, a high-efficiency IOT is an electron-beam-driven RF source employed in the UHF band that offers high efficiency at variable output power levels. In this talk, we show the progress of developing a 1.3 GHz HEIOT in...
Beam injection systems in hadron colliders require kickers generating ±50 kV peak voltages into a 50 Ω impedance, with peak currents of 1000 A and sub-10 ns rise and fall times. This paper presents a novel high-voltage pulse power generator utilizing a dis-tributed pulser architecture. It combines gallium nitride (GaN) transistors in a Marx to-pology with an inductive adder, achieving...
The Single Stretched Wire (SSW) method allows highly precise integral field measurements by recording voltage across a tensioned wire mounted to 2-axis linear stages at either end of the magnet aperture. However, traditional SSW probes are not well suited for curved accelerator magnets, which are essential for steering charged particles along arced trajectories in storage rings or beamlines....
We report on the quantum efficiency (QE) and mean transverse energy (MTE) of photoemitted electrons from cadmium arsenide (Cd3As2), a three-dimensional Dirac semimetal (3D DSM) of interest for photocathode applications due to its unique electronic band structure, characterized by a 3D linear dispersion relation at the Fermi energy. Samples were synthesized at the National...
Plasma-based accelerators offer a promising route to compact high-energy particle sources. However, recent theoretical work* has suggested that accelerating a low-energy-spread electron beam may not be feasible at high efficiency because of the excitation of transverse beam break up (BBU) instability. This instability, which leads to a growing spatio-temporal oscillations of the beam centroid,...
Dielectric-lined waveguides are a promising platform for high-gradient beam-driven dielectric wakefield acceleration (DWFA). We present experimental results from a recent study at the Argonne Wakefield Accelerator (AWA), focusing on the performance of three copper-coated dielectric structures with distinct cross-sections: circular, rectangular, and square. These geometries enable a comparative...
The IOTA ring is vital to the advancement of accelerator sciences, and a large part of its attractiveness to accelerator physicists is its modularity and the versatility that this function provides. Up until this point, the FAST accelerator has provided electron beam for the studies in IOTA. With the soon to be commissioned IOTA Proton Injector in lieu, the requirement for better vacuum to...
Embedded control design often requires extensive engineering time. Development boards, while useful, provide minimal peripherals for complex projects. A modular Field Programmable Gate Array (FPGA) controller printed circuit board (PCB) was designed which reduces concept to implementation time dramatically. A low cost flash embedded FPGA was chosen for this board which helped reduce components...
This paper discusses the types of faults seen by the 805MHz CCL (side Coupled Cavity Linac) high power Los Alamos Neutron Science Center RF klystron-modulator system. Failures leading to beam down time are tracked across various years and underlying failure causes leading to these high-power RF issues are discussed. The biggest culprits causing significant downtime from the klystron and the...
Plasma wakefield accelerators (PWFA) are promising candidates for next-generation colliders due to their ability to sustain extremely high acceleration gradients. Laser-ionized plasma sources offer key advantages for PWFA, including precise control over the transverse and longitudinal plasma density profiles for emittance preservation, tunable plasma column widths suited for positron...
Plasma Wakefield Acceleration (PWFA) can provide 10’s of GeV/m acceleration gradients, providing a novel path towards efficient and compact future colliders and high brightness free electron lasers. At the Facility for Advanced Accelerator Experimental Tests II (FACET-II) at SLAC, we are undertaking experiments in PWFA using a 10 GeV electron beam configured as a drive and witness pair. We...
" High quantum efficiency (QE) semiconductor photocathodes are essential for generating high average beam current and brightness. One class of semiconductor photocathodes considered for use in photoinjectors for unpolarized and polarized electron beams are III-nitride heterostructures. These materials can exhibit negative electron affinity at the surface, utilizing intrinsic polarization...
An often-overlooked aspect of Low Level Radio Frequency (LLRF) design is commissioning of a new system. During Jlab’s Scheduled Accelerator Maintenance (SAM) in 2024, two C75 Cryomodule were installed in CEBAF with Jlab’s LLRF 3.0 system. Jlab’s team has invested effort in automating and standardizing their commissioning process. Several key components are klystron characterization, cavity...
As part of the Advanced Photon Source Upgrade (APS-U), approximately one thousand bipolar power supplies were installed to power the slow corrector magnets. During the APS-U commissioning, a 1Hz harmonic was detected in the beam motion. This harmonic originates from the 480V AC grid, caused by the booster ramping power supply operating at 1 Hz. The resulting grid disturbance introduced...
New 0.5m long SCU prototypes were designed based on lessons learned from the previous full length (1.5 m) core experiences. The original monolithic cores have all steel poles. The new cores have plastic back poles to avoid electrical shorts of superconducting wires to cores. Magnetostatic calculation was made for one period model for each of two designs under consideration. Then,...
Structured plasma channels are an essential technology for driving high-gradient, plasma-based acceleration and control of electron and positron beams for advanced concepts accelerators. Laser and gas technologies can permit the generation of long plasma columns known as hydrodynamic, optically-field-ionized (HOFI) channels, which feature low on-axis densities and steep walls. By carefully...
Beam brightness can be enhanced with high gradient operation in photocathode guns. Such high gradient guns, such as the L-band gun at the Argonne Wakefield Accelerator (AWA) facility and the C-band high gradient gun being commissioned in the CARIE project at Los Alamos National Laboratory, are also typically equipped with semiconductor photocathodes due to their high quantum efficiency. To...
A new high-power RF test facility was developed at the Los Alamos Neutron Science Center (LANSCE) to evaluate components of a RF Solid-State Amplifier (SSA) system operating at 805 MHz and targeted for a final output power of 1.25 MW. The system is powered by a 100 V DC supply and stabilized with a 0.1 F capacitor bank to support transient power demands, capable of storing up to 1.125 kJ of...
The NSLSII storage ring contains over 180 RF shielded bellows over its 792 m circumference. Three of these bellows are instrumented with RTD temperature sensors on the internal components to monitor and validate expected performance. The temperature data showed an increasing internal temperature trend during successive 500mA beam operation on one of these bellows. This bellows and many other...
Design of radio frequency (RF) couplers and diagnostics require a good understanding of the electromagnetic mode patterns of RF cavities. This study investigates the adiabatic transformation of transverse magnetic (TM) modes in a cylindrical cavity into transverse electromagnetic (TEM) modes of a coaxial cavity by gradually introducing an inner conductor. Using CST Studio Suite, we simulate...
FACET-II is a National User Facility offering unique capabilities for the advancement of accelerator science. Utilizing high-energy electron beams, it enables state-of-the-art research in advanced acceleration methods, ultra-high-brightness beam generation, and novel radiation sources. Here, we provide an overview of the FACET-II facility and highlight its experimental infrastructure, which is...
The beam-driven, passive plasma lens can provide axisymmetric focusing with strengths orders of magnitude greater than conventional quadrupole magnets, while remaining ultra-compact. These characteristics make it attractive for beam matching into a plasma wakefield accelerator and for controlling beam divergence downstream of plasma stages. Optimal performance can be achieved in the underdense...
Medium temperature baking (300- 350 °C) enhances the quality factor of niobium superconducting radio frequency cavities. However, surface contamination introduced during vacuum furnace baking limits the quench field and may also degrade the quality factor of the cavity. To investigate this effect, a 1.3 GHz single-cell Nb cavity underwent mid-T baking, followed by a chemical treatment to...
Plasma processing of superconducting radio frequency (SRF) cavities has been an active research effort at Jefferson Lab (JLab) since 2019, aimed at enhancing cavity performance by removing contaminants and reducing field emission. The work includes plasma treatment of single-cell cavities, cavity pairs, and in-situ processing of cryomodules. Compared to earlier CEBAF cavities (C20/50 and C75),...
A distributed-drive linac consists of individually powered and phased single- cell cavities. In this paper, we evaluate options for coupling RF power into the linac cavities, and present an initial design for a cavity frequency tuning mechanism.
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...
High gradient photoinjector is an important tool to generate high brightness electron beams for scientific applications. Since then, research and development of high accelerating gradient photoinjectors has been an important topic to generate even brighter electron beams. However, high gradient photoinjectors suffer issues from material breakdown due to extremely high surface electric fields....
The Optically Pumped Polarized Ion Source (OPPIS) has been providing polarized H- ions to the injector chain of the Relativistic Heavy Ion Collider (RHIC) since 2000. The OPPIS has undergone several upgrades. The latest upgrade, completed in 2022, included several improvements. Optimizing the Rb and Na cells has mitigated vapor dispersion in the beamline, resulting in a significant reduction...
Plasma acceleration is an innovative principle characterized by high acceleration gradients, which has attracted significant interest from major accelerator laboratories worldwide, because of its potential to increase accelerator energy and reduce size. One promising approach involves using existing conventional accelerators as external injectors for plasma-based accelerators, a topic of...
The cathodes and RF interaction at extremes (CARIE) is a project in Los Alamos National Laboratory (LANL) that aims for generating a high-brightness electron beam from a high-gradient photocathode. The commissioning of the CARIE facility started in 2022. A 50 MW C-band klystron was conditioned in 2023. A waveguide line including a high-power circulator was constructed and conditioned up to 12...
Several attractive features of a novel electron Cyclotron Resonance Accelerator (eCRA) include: a compact robust room-temperature single-cell RF cavity as the accelerator structure; continuous ampere-level high current output without bunching; and a self-scanning accelerated energetic e-beam, obviating need for a separate beam scanner. Hence an eCRA can be highly compact and efficient to...
The ongoing work related to the LDRD funded by JLab is investigating the effects of radiation on permanent magnet materials intended for use in the CEBAF energy upgrade. This effort combines experimental exposure of magnet samples to radiation rates within the accelerator with detailed simulation studies. Samples are positioned at various locations to capture a range of radiation environments,...
A feasibility study is developing a prototype solid state power amplifier to supplant or replace 805 MHz klystrons powering the coupled-cavity linac at the Los Alamos Neutron Science Center (LANSCE). We are considering the RF passive hardware used for such an amplifier. The power from individual transistor pallets that provide 5 kW each must be power-combined to the requisite 1.25 MW needed to...
The Los Alamos Neutron Science Center (LANSCE) uses forty-four (44) 1.25-MW 805-MHz klystrons to power its side-Coupled Cavity (CCL) linear accelerator (LINAC). In recent years, the facility has experienced a significant klystron failure rate and dwindling hot spare inventory, producing ample beam downtime and reliability risk. This paper presents a LANSCE case study on rebuilding a klystron,...
LANSCE uses a duoplasmatron ion source to produce H+ ion beams for the Isotope Production Facility, which uses 100 MeV proton beams to produce a variety of therapeutic and diagnostic isotopes for research purposes and also supports a variety of other experiments for materials and nuclear physics. We have recently begun work to improve the reliability, peak current, and lifetime of the ion...
The first 100 MeV of acceleration for protons and H- ions at the Los Alamos Neutron Science Center (LANSCE) is presently accomplished with a Cockroft-Walton generator (750 keV), followed by four Alvarez drift tube linac (DTL) cavities commissioned in 1970. The RF duty factor is 12 %, leading to significant thermal loading in the room temperature copper structures. Increasing obsolescence and...
Recent experimental studies at the Argonne Wakefield Accelerator (AWA) have shown that operating RF cavities with short pulses, only a few nanoseconds in duration, can raise the accelerating gradient to nearly 400 MV/m in a series of X-band structure tests. These results motivate further investigation into the breakdown physics underlying the short-pulse acceleration regime.
In this work, we...
The FACET-II 10 TW laser system enables a variety of studies ranging from plasma wakefield acceleration over laboratory astrophysics to strong-field QED. While we successfully improved the performance of the high-energy laser-arm has, the much more versatile low-energy arm has yet to keep up. We report on the currently ongoing efforts to improve the performance of the low-energy laser-arm...
Positrons and electrons can be generated by impinging a relativistic electron beam onto a solid converter, sometimes referred to as a non-neutral fireball beam. Depending on the scenario, a substantial fraction of the incoming driver bunch may still have sufficient quality to drive high gradient (~GV/m) accelerating wakefields in a dielectric structure. Here we consider the design of a...
Nb₃Sn has emerged as a leading alternative material due to its higher superconducting critical temperature (Tc) and superheating field (Hsh), promising a viable solution to the intrinsic performance limit currently faced by Nb superconducting radiofrequency (SRF) cavities. We sputter-coated Nb₃Sn inside Nb SRF cavity using a stoichiometric Nb₃Sn tube target in a DC cylindrical magnetron...
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...
With the current designs of spin-polarized particle accelerators such as the Future Circular Collider (FCC) at CERN and the Electron-Ion Collider at BNL well-underway, there is presently a strong need for an efficient and modern spin tracking code. The multi-scale nature of spin-orbit dynamics dictates the use of high order algorithms and sympathetic integration, while the overall complexity...
This paper describes the testing procedure for LANSCE 805 MHz klystrons and describes the current klystron test facility. The 1.25 MW klystrons used for powering LANSCE CCL (side Coupled Cavity Linac) are tested during first installation or after a fault in the modulator system. This klystron testing process is expert dependent and typically takes longer than 1 month to execute. The klystron...
We present designs and plans for a compact positron source that can deliver low-emittance beams for experiments*. The source is based on a Penning-Malmberg trap. We discuss positron generation and extraction, with specific focus on bunch manipulation at the exit of the trap. We describe a number of exciting science opportunities enabled by the Compact Positron Source.
Beam Alpha developed a kilowatt-scale fusion microreactor that directly converts nuclear energy to electrical energy without intermediate heat steps. This device has an output of 1.6 million volts DC. A converter is needed to transform this potential energy into useful electrical power. To achieve this the "Pulsed Ion Reflex Klystron" has been developed. The PIRK aims to achieve high...
The SCU cryostat, featuring two 1.5-meter-long Nb-Ti superconducting undulators (SCUs), is currently being built for the Advanced Photon Source Upgrade. The final design, along with the thermal and mechanical models of this cryocooler-cooled, liquid helium-based cryostat, has been completed. The cryostat has been fabricated, and preliminary cool-down tests were conducted both with and without...
The Facility for Rare Isotope Beams (FRIB) produces high-intensity, high-purity rare isotope beams through interactions between a primary beam and a graphite production target, currently operating at approximately 20 kW of primary beam power. To absorb unreacted primary beams downstream of the production target, an intermediate beam dump, called the minichannel beam dump (MCBD), was developed...
Detecting terahertz (THz) radiation in ultra-high vacuum (UHV) environments presents notable challenges due to the limited availability of commercially compatible components. In preparation for upcoming THz measurements at the Argonne Wakefield Accelerator (AWA) facility, we investigated two critical aspects: (1) the THz transmission characteristics of fused silica windows, and (2) the...
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...
Shaping ultraviolet (UV) laser beams is critical for optimizing photoinjector performance for applications in free-electron lasers (FELs). It has been shown that a 50% truncated Gaussian beam can achieve the lowest emittance via space charge compensation at LCLS-I. However, conventional shaping techniques to prepare this beam are limited by significant power losses or are not adapted for UV...
SRF photoguns become a promising candidate to produce highly stable electrons for UEM/UED applications because of the ultrahigh shot-to-shot stability compared to room temperature RF photoguns. SRF technology was prohibitively expensive for industrial use until two recent advancements: Nb3Sn and conduction cooling. SRF gun can provide a CW operation capability while consuming only 2W of RF...
Throughout its operation, the RHIC triplet magnets have been subject to a mechanical vibration around 10 Hz. These mechanical vibrations were found to produce a beam orbit jitter that was detrimental to the collider luminosity. During RHIC operation, this has been effectively mitigated by the implementation of a fast feedback orbit control system. For the Electron Ion Collider (EIC) Hadron...
There is increasing interest in developing accelerator technologies for space missions, particularly for fundamental science. In order to meet these mission needs, key accelerator technologies must be redesigned to be able to function more reliably and efficiently in a remote and harsh environment. In this work we focus on a modest electron injector system, specifically the traditional...
The Argonne Wakefield Accelerator (AWA) facility operates a high-charge (100s of nC) electron beam in a bunch train, with eight electron bunches at a 769 ps spacing matching the linac operating frequency of 1.3 GHz. AWA’s electron beam is optimized for producing large wakefields in resonant structures to study structure wakefield acceleration. This is achieved by maximizing total beam charge,...
This work investigates AISI 1020 low-carbon steel as an alternative material for extreme-high vacuum (XHV) chambers in spin-polarized electron sources, addressing a critical limitation in high-current applications. We compare bare and magnetite-coated steel chambers to determine optimal surface conditions for accelerator applications. Our findings reveal that bare steel, following appropriate...
A new Higher Order Mode (HOM) damper was designed and is undergoing testing for the Booster accelerator cavity at Fermilab. In anticipation of the PIP-II upgrade, it was discovered that the higher intensity of PIP-II may cause beam instability due to an excited mode at 106 MHz. This unfortunately corresponds with the cavity’s 2nd order harmonic mode, which will sweep from 86-105.7 MHz. The new...
