1. RFQ A Radio Frequency Quadrupole(RFQ)is favored for low energetic beams. It bunches, accelerates and focuses the ion beam. The 4-vane REXRFQ accelerates the radioactive ions with a charge-to-mass ratio larger than 1/4.5 from 5 keV/u to 300 keV/u. • Theory • In principle an RFQ can be divided into four sections: the radial matching section, the shaper, the buncher, and the accelerator section. • The 4-vane RFQ consists of four electrodes, on which an alternating voltage field is applied. The RF quadrupole field provides transverse focusing for the low energy ions while a modulation of the spatial length of the four rods performs smooth bunching of the injected dc-beam and acceleration. • Data • Energies Ein = 5 keV/u, Eout = 300 keV/u • Tank length L = 3 m • No. of cells: 232 • Electrode voltage Vrod = 42 kV • Peak power consumption Wpeak = 53 kW • Shunt impedance R = 100 km • Q = 4000 • Longitudinal phase spread = ±14% • Longitudinal energy spread W/W = ±1.5% Beam direction RF