Figure from:Overview of Beam Diagnostic Systems for FRIB

Figure 5 Warm section diagnostic box, with wire profile monitor, BPM, and halo monitor ring. The profile monitor (shown) is absent in stations between cryomodules. Halo Monitor Rings [7] with apertures closely matching the physical apertures of the cryomodules are installed in the warm sections between cryomodules (Fig. 5). They are capacitively-coupled to the electrical ground of the diagnostic box and provide a measurement of intercepted current (down to ~10 nA) whether from halo scraping or transverse excursions of the beam core. Current work is examining the optimum ring aperture as a compromise between detection sensitivity, tuning flexibility, and ring lifetime.

Related Figures (9)

Table 1: Representative Ion Species in FRIB

Figure 1: Schematic layout of FRIB drive accelerator facility.

Figure 2: Schematic of diagnostic systems in the FRIB Front End. ion source lines in the FRIB front-end (Fig. 2) will each include a diagnostic station, capable of intercepting up to 300 W of continuous beam power, comprising (i) horizontal and vertical charge-selecting slits; (ii) a Faraday cup; (iii) view screen and optics; and (iv) horizontal and vertical Allison scanners [9].

Figure 4: Cryogenic BPM installed between solenoid and cavity in LS1 (left), and cryogenic cable assembly (right). There are a total of 39 cold BPMs integrated with the LS1 cryomass assemblies. Steel jacketed, ceramic dielectric (SiO), 50 Ohm cables are used within the cryomodule insulating vacuum to carry the BPM signals from the ~4 K beam line to a 300 K feedthrough. The small cable diameter (0.090 inch) limits the static heat oad presented to the cryogenic system. This system has been installed on the prototype FRIB 0.085 cryomodule cold mass, and verified with a network analyser at ambient and cryogenic temperatures [11].

Figure 3: FRIB wire profile monitors. Flapper (top), Small (left), Large (right). sections between cryomodules (Fig. 5). In the two higher energy linac segments (LS2 and LS3), BPMs are located only in the warm sections between cryomodules.