Progress with the 2Q-LEBT Facility for the RIA Project
The design goal of 400 kW uranium beam in the Rare Isotope Accelerator (RIA) Driver Linac can be achieved employing a concept of simultaneous acceleration of two charge states. It has been undertaken to build a prototype 2Q-injector of the RIA Driver Linac which includes an ECR ion source, a LEBT and one-segment of the prototype RFQ. The project called the 2Q-LEBT Facility is being developed in the Physics Division of ANL. Currently, the 2Q-LEBT Facility consists of BIE-100 ECR ion source. The reassembly and commissioning of the source has been completed. During the commissioning process we redesigned and manufactured a few components of the source to increase the beam production performance. A new diagnostic station has been designed and built for accurate measurements of the output beam emittance. The further development of the 2Q-LEBT Facility comprises installation of the source on 100 kV high-voltage platform, building an achromatic bending and transport system including the multi-harmonic buncher, and a full power 57.5 MHz RFQ segment. This report includes a detailed description of the 2Q-LEBT design and beam dynamics simulations along with emittance measurements for various beams.
Design of 57.5 MHz CW RFQ for medium energy heavy ion superconducting linac.
The nuclear science community considers the construction of the Rare Isotope Accelerator (RIA) facility as a top priority. The RIA includes a 1.4 GV superconducting linac for production of 400 kW cw heavy ion beams. The initial acceleration of heavy ions delivered from an electron cyclotron resonance ion source can be effectively performed by a 57.5 MHz 4-m long room temperature RFQ. The principal specifications of the RFQ are (i) formation of extremely low longitudinal emittance, (ii) stable operation over a wide range of voltage for acceleration of various ion species needed for RIA operation, and (iii) simultaneous acceleration of two-charge states of uranium ions. cw operation of an accelerating structure leads to a number of requirements for the resonators such as high shunt impedance, efficient water cooling of all parts of the resonant cavity, mechanical stability together with precise alignment, reliable rf contacts, a stable operating mode, and fine tuning of the resonant frequency during operation. To satisfy these requirements a new resonant structure has been developed. This paper discusses the beam dynamics and electrodynamics design of the RFQ cavity, as well as some aspects of the mechanical design of the low-frequency cw RFQ.
Temperature Dependence of Irradiation-Induced Magnetic Flux Loss in Nd2Fe14B Permanent Magnets
Nd2Fe14B permanent magnets were irradiated with 20 MeV protons at 300 K and at 15 K, and the flux loss was measured as a function of the irradiation dose. The results show that at 15 K the Nd2Fe14B magnets can withstand particle radiation at least 1000 times more than at room temperature.