High field hybrid photoinjector electron source for advanced light source applications

The production of high spectral brilliance radiation from electron beam sources depends critically on the electron beam qualities. One must obtain very high electron beam brightness, implying simultaneous high peak current and low emittance. These attributes are enabled through the use of very high field acceleration in a radio-frequency (rf) photoinjector source. Despite the high fields currently utilized, there is a limit on the achievable peak current in high brightness operation, in the range of tens of Ampere. This limitation can be overcome by the use of a hybrid standing wave/traveling wave structure; the standing wave portion provides acceleration at a high field from the photocathode, while the traveling wave part yields strong velocity bunching. This approach is explored here in a C-band scenario, at field strengths (>100 MV/m) at the current state-of-the-art. It is found that one may arrive at an electron beam with many hundreds of Amperes with well-sub-micron normalized emittance. This extremely compact injector system also possesses attractive simplification of the rf distribution system by eliminating the need for an rf circulator. We explore the use of this device in a compact 400 MeV-class source, driving both inverse Compton scattering and free-electron laser radiation sources with unique, attractive properties

A COMPACT LINAC DESIGN FOR AN ACCELERATOR DRIVEN SYSTEM*

Abstract A compact linac design has been developed for an Accelerator Driven System (ADS). The linac is about 150 meters in length and comprises a radio-frequency quadrupole (RFQ) and 20 superconducting modules. Three types of half-wave cavities and two types of elliptical cavities have been designed and optimized for high performance at frequencies of 162.5, 325 and 650 MHz. The lattice was designed and optimized for operation with a peak power of 25 MW for a 25 mA -1 GeV proton beam. The cavities RF design as well as the linac lattice will be presented along with end-to-end beam dynamics simulations for beam currents ranging from 0 to 25 mA. Optimized superconducting cavity design for high voltage and low cryogenic losses. Superconducting solenoid focusing inside cryomodules to minimize warm transitions and consequently the number of required cryomodules. Cold BPMs attached to SC cavities inside the cryomodule to reduce the number of diagnostics required between cryomodules Horizontal and vertical steering correctors are built into the solenoids requiring no additional space for correctors along the beam-line. With these considerations, the drift space between cryomodules is reduced, benefiting the beam dynamics from a more periodic focusing and acceleration sequence. COMPACT LINAC LAYOUT RF CAVITIES DESIGN The base linac frequency is 162.5 MHz, it was mainly chosen because the CW RFQ requires less power and is more reliable in operation than at 325 MHz for example. At this frequency, half-wave (HWR) and single-spoke (SSR) resonators are more efficient for beta < 0.6 than other resonators. HWRs were chosen because of the mature fabrication and processing technologies available at Argonne

Multicomputer system dedal-2 for local landscape monitoring

The paper contains the description of a multicomputer system for terrestrial surface automatized monitoring. The system is able to detect moving objects on the terrain considered, to locate static objects which appear/disappear on terrain as well as to recognize such objects. The system uses photosnapshot the terrain and a set of reference images for recognition

Design and multiphysics analysis of a 176 MHz continuous-wave radio-frequency quadrupole

We have developed a new design for a 176 MHz cw radio-frequency quadrupole (RFQ) for the SARAF upgrade project. At this frequency, the proposed design is a conventional four-vane structure. The main design goals are to provide the highest possible shunt impedance while limiting the required rf power to about 120 kW for reliable cw operation, and the length to about 4 meters. If built as designed, the proposed RFQ will be the first four-vane cw RFQ built as a single cavity (no resonant coupling required) that does not require π-mode stabilizing loops or dipole rods. For this, we rely on very detailed 3D simulations of all aspects of the structure and the level of machining precision achieved on the recently developed ATLAS upgrade RFQ. A full 3D model of the structure including vane modulation was developed. The design was optimized using electromagnetic and multiphysics simulations. Following the choice of the vane type and geometry, the vane undercuts were optimized to produce a flat field along the structure. The final design has good mode separation and should not need dipole rods if built as designed, but their effect was studied in the case of manufacturing errors. The tuners were also designed and optimized to tune the main mode without affecting the field flatness. Following the electromagnetic (EM) design optimization, a multiphysics engineering analysis of the structure was performed. The multiphysics analysis is a coupled electromagnetic, thermal and mechanical analysis. The cooling channels, including their paths and sizes, were optimized based on the limiting temperature and deformation requirements. The frequency sensitivity to the RFQ body and vane cooling water temperatures was carefully studied in order to use it for frequency fine-tuning. Finally, an inductive rf power coupler design based on the ATLAS RFQ coupler was developed and simulated. The EM design optimization was performed using cst Microwave Studio and the results were verified using both hfss and ansys. The engineering analysis was performed using hfss and ansys and most of the results were verified using the newly developed cst Multiphysics package

Beam Dynamics for a High Field C-Band Hybrid Photoinjector

In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a 4 MeV beam with ∼ 20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ∼ 0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a 0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of < 400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations