Fermilab, Batavia, USA
The Fermilab High Intensity Neutrino Source (HINS) project is intended to test new concepts for low-energy, high-intensity superconducting linacs. HINS initial design consists of a 50 KeV ion source, a 2.5 MeV Radiofrequency Quadrupole (RFQ) followed by room temperature and superconducting spoke resonator acceleration sections. At present, a proton ion source and the 325 MHz RFQ, followed by a beam diagnostics section, have been operated with beam. This paper will present the beam measurement results for the proton ion source and for the 325 MHz RFQ module. In addition, this paper will discuss the role of HINS as a test facility for the development of beam diagnostic instrumentation required for future high-intensity linacs.
LBNL, Berkeley, California, USA
Fermilab, Batavia, USA
Laser-based position diagnostics for hydrogen ion (H−) beams typically use high power optical pulses that must be transported via free space to the diagnostic point. It is difficult to maintain stable alignment through such systems, especially when multiple channels are required. We describe a method for distributing low power, amplitude modulated pulse trains via fiber optic, and detecting interaction with the H− beam by synchronous detection of the stripped electrons. Trains of 10 ps, 1064 nm pulses at 400 MHz repetition rate are modulated by a 1 MHz signal that is the reference for a lockin amplifier. The average beam power is below one Watt. Synchronous detection at RF frequencies allows for efficient noise rejection when using optical powers below the nonlinear (Raman scattering) threshold of an optical fiber. The laser is synchronized with the bunch repetition rate, so the diagnostic can be used for bunch length measurements as well. We present results of tests of the optical system with 100 m, single-mode fiber and realistic detected signal levels, demonstrating detection of the modulation signal with high signal-to-noise ratio and low nonlinearity.