A Spiral-Resonator Radio-Frequency Quadrupole Accelerator Structure

Abstract

A radio-frequency quadrupole (RFQ) structure operating at low frequency has been developed for possible use in accelerators for heavy ion fusion or Tokamak plasma heating. The structure uses a series of shunt spiral inductors placed periodically along the electrodes of an electric quadrupole to achieve resonance at the desired frequency. A 1.2-m-long model has been constructed for low-power testing. The model resonates near 12 MHz and has radial dimensions that are reduced by a factor of 15 compared to the commonly used four-vane resonator.

Development and testing of 37.8 MHz, 3.0 kW RF amplifier system for Radioactive Ion Beam facility at VECC Kolkata

“…The resonance frequency of buncher is 37.79 MHz and the Q-value (Unloaded) is about 2350. The measured shunt impedance is ∼ 46 kΩ, which has been measured using the admittance variation method [25,26]. The capacitive tuner of the re-buncher is moved linearly over a distance of 20 mm.…”

Longitudinal bunch length measurement of RFQ beam using in-house developed detector system

“…Frequency tuning was achieved using capacitive tuner. The shunt impedance has been measured using capacitance variation method [23,24] while bead perturbation technique [25] was utilized to ascertain electric field pattern between the deflector plates.…”

Development of deflector cavity and RF amplifier for bunch length detector system

“…The measured and simulated electric field profiles are compared in figure 3(b). The shunt impedance R, which is also an important parameter for estimation of required power in the cavity, was estimated by the capacitance variation method [31,32]. In this method the inter electrode capacitance of deflector is perturbed by putting a known small dielectric sheet between the plates.…”