LBNL, Berkeley, California, USA
Project X is proposed as a high intensity proton facility at Fermilab to support a world-leading program in neutrino and flavor physics over the next several decades. The front-end consists of an H− ion source, low-energy beam transport (LEBT), and 162.5 MHz CW Radio-Frequency-Quadrupole (RFQ) accelerator. The LEBT design, currently under study at LBNL, would comprise two solenoids, a dipole magnet and a chopper. The LEBT chopper is designed to achieve 1 MHz beam chopping of a partially neutralized 30 keV, 5 mA H− beam. Preliminary simulation studies show that chopping the beam before the second solenoid is more efficient in terms of chopper bias voltages. However, the space charge neutralization will be lost along the beam after the chopper and through the second solenoid. A beam dynamics study, using WARP 3D (a Particle-in-cell simulation code), has been carried out to investigate both the time-dependence of the partial neutralization in the segment after the chopper, as well as the beam stability and emittance growth. Benchmark experiments are ongoing and simulation and experimental results will be presented in this Workshop.
