PMQ

For these applications the control of the field quality is very important because the contribution of harmonic field components different from the quadrupole can distort the beam, producing an emittance increase or a reduction of the beam transmission in the accelerating structure. The dipole component is the most undesirable one, because the propagation of the proton beam in the small aperture SCDTL structure (4 mm diameter bore hole) requires a coincidence of ±50 µm of the magnetic and mechanical axis. To achieve this purpose the PMQ harmonic field center position has to be measured with high accuracy.

The simple quick and low cost method described here consists in keeping fixed the coil and rotating around it the small PMQ under measurement mounted on a lathe. In such way the accuracy in the determination of the center of the harmonic field is few micrometers. The signal of the induced voltage on the coil is analyzed by Fast Fourier Transform (FFT) to obtain the field component amplitudes.

Small aperture high gradient permanent magnet quadrupoles are used to focus particles

Small aperture high gradient permanent magnet quadrupoles1,2,3,4,5 are of particular interest for focusing particles in compact accelerator setup based on high frequency accelerators injected by conventional injectors or ion laser sources. An example is given by the 3GHz SCDTL (Side Coupled Drift tube Linac) proton accelerating structure consisting in short DTL tanks coupled by side coupling cavities using for particle focusing small 3 cm long PMQs with a gradient around 200 T/m placed in the inter-tank space.

· SCDTL-1

· SCDTL-2

· SCDTL-3

· SCDTL-4

· SCDTL-5

· SCDTL-6

· SCDTL-7

· SCDTL-8

· PMQ

PMQ

SUBSYSTEMS

INJECTOR LEBT SCDTL CCL RF SYSTEM DIAGNOSTICS DOSIMETRY CONTROL SYSTEM RADIOPROTECTION