Welcome to IRIS !

The compact 6.4 GHz ECR ion source IRIS (Ion source for Radioactive ISotopes) has been developed for the production of low to medium charge state radioactive ion beams [references: ECRIS97, ICIS97, HIAT98, PAC99].

Fig.1: Experimental Setup of IRIS.

The ion source consists of only one plasma stage. The microwave is launched through an off-axis wave-guide (see figure 2) terminated at a bias plate in the injection region. The aluminum plasma chamber has a diameter of 13.5 cm and the magnetic-mirror length is 28.3 cm, providing a relatively large plasma volume of 5 liters. The plasma chamber is double-walled to accommodate cooling water. The mirror field reaches a maximum field of 0.7 Tesla at the injection and 0.4 Tesla at the extraction. At the plasma chamber-wall the sextupole-field strength reaches 0.32 Tesla.

Fig.2: Injection flange of IRIS with waveguide launching, gas inlet and electrical connections.

Fig.3: A cross-sectional view of the LBNL IRIS ion source.
(click figure for enlarged picture)

The IRIS project is initially focused on the production a low energy 14O ion beam (30 keV) to measure the energy shape of the beta decay spectrum. 14O is generated in the form of CO in a high temperature carbon target (see figure 4) using a 20 MeV ³He+ beam from the LBNL 88-Inch Cyclotron via the reaction 12C(3He,n)14O.(link). An 8 m stainless steel transfer line connects the target chamber to an ECR ion source through a turbo molecular pumping stage (see figure 1). Thus, the turbo pump separates the target vacuum chamber from the ion source. The gas coming from the turbo pump is fed into the ion source and ionized, extracted at energies of 20 to 30 keV and mass separated.

Fig.4: Hot Carbon Target for the 14O production.