LBNL, Berkeley, California, USA
WEOAA1
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
JLAB, Newport News, Virginia, USA
Fermilab, Batavia, USA
We present an overview of design studies and R&D toward NGLS a Next Generation Light Source initiative at LBNL. The design concept is based on a multi-beamline soft x-ray FEL array powered by a CW superconducting linear accelerator, and operating with a high bunch repetition rate of approximately 1 MHz. The linac design uses TESLA and ILC technology, supplied by an injector based on a CW normal-conducting VHF photocathode electron gun. Electron bunches from the linac are distributed by RF deflecting cavities to the array of independently configurable FEL beamlines with nominal bunch rates of ~100 kHz in each FEL, with uniform pulse spacing, and some FELs capable of operating at the full linac bunch rate. Individual FELs may be configured for different modes of operation, including self-seeded and external-laser-seeded, and each may produce high peak and average brightness x-rays with a flexible pulse format.
LBNL, Berkeley, California, USA
USTC/NSRL, Hefei, Anhui, People's Republic of China
The commissioning at the Lawrence Berkeley National Laboratory (LBNL) of a high-brightness high-repetition rate (MHz-class) photo-gun, based on a normal conducting 186 MHz (VHF-band) RF cavity operating in CW mode, is now completed. The gun has been designed to satisfy the requirements for operating high-repetition rate 4th generation light sources. Test of high quantum efficiency photocathodes with bunches of hundreds pC at MHz repetition rate are now underway. They include, Cs2Te cathodes developed in collaboration with INFN-LASA and multialkali antimonides (CsK2Sb), prepared by a collaborating group at LBNL. The present experimental results and the plan for future activities are presented.
LBNL, Berkeley, California, USA
The Project X Injector Experiment (PXIE), a prototype front end of the Project X accelerator [1] proposed by Fermilab, is currently under construction. The complete PXIE beamline [2] is made up of an H− ion source, a low-energy beam transport (LEBT), a 2.1 MeV, 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, a medium-energy beam transport (MEBT) and a 30 MeV section of superconducting cryomodules. The 4.45 m long CW RFQ consists of four separate modules that are joined by means of specially designed bolted joints. Each module consists of four solid copper vanes that are brazed together to form a 4-quadrant accelerating cavity. The ~80 kW of total wall power heat is removed by means of gun drilled water cooling passages. Mode stabilization is provided by a series of brazed, water cooled pi-mode rods. Tuning is achieved using a total of 80 fixed slug tuners. Fabrication of the PXIE RFQ is now under way at LBNL. Details of the RFQ mechanical design and an update of the fabrication progress are presented in this paper.
LBNL, Berkeley, California, USA
PXIE (Project X Injector Experiment) is a prototype front end system for the proposed Project X accelerator complex at Fermilab. An integral component of the front end is a 162.5 MHz normal conducting CW (continuous wave) radio-frequency quadrupole (RFQ) accelerator that has been designed and will be fabricated by LBNL. The RFQ will accelerate H− ions from 30 keV to 2.1 MeV [2]. The four-vane RFQ will consist of four modules with a total length of 4.45 meters. Through rigorous application of finite element analysis (FEA), the electromagnetic fields and their resultant effect on the RFQ body temperature and the subsequent deformations due to thermal expansion have been simulated. The analysis methodology developed at LBNL allows for quick evaluation of RFQ temperature, stress, deformation and the resulting effect on frequency without requiring the construction of a prototype. The technique has been applied to the following: RFQ body, RFQ cutbacks, fixed slug tuners, and pi-mode rods. The analysis indicates that the total heat load on the RFQ walls will be approximately 80 kW, which is removed via water-cooled passages.
LBNL, Berkeley, California, USA
The Project X Injector Experiment (PXIE) now under construction at Fermilab is a prototype front end of the proposed Project X accelerator [1]. PXIE will consist of the following: an H− ion source, a low-energy beam transport (LEBT), a radio-frequency quadrupole (RFQ) accelerator, a medium-energy beam transport (MEBT) and a section of superconducting cryomodules [2]. The PXIE system will accelerate the beam from 30 keV to 30 MeV. The four-vane, brazed, solid copper design is a 4.45 m long CW RF accelerator with a resonant frequency of 162.5 MHz. The RFQ will provide bunching and acceleration of a nominal 5 mA H− beam to an energy of 2.1 MeV. The average power density on the RFQ cavity walls is <0.7 W/sq. cm such that the total wall power losses are ~80 kW. LBNL has completed the final design of the PXIE RFQ, and fabrication is now under way. The completed PXIE RFQ will be assembled at LBNL and tested with low-level RF prior to shipping to Fermilab. Several aspects of the final RFQ mechanical design along with associated fabrication techniques are presented in this paper.