Transmission Properties of a 4-MeV C⁺ Ion Beam Entering a Narrow Gap between Two Cylindrical Glass Surfaces

Abstract

To investigate the possibility of guiding a fast, heavy-ion beam with tilted curved surfaces, we study the transmission properties of a 4 MeV C+-ion beam passing through a narrow gap between a convex glass lens and concave glass lens. The ion-beam transmission of 42–59% obtained at the tilt angle θ= 3° is 20–30 times greater than that of 2% estimated from the cross section of the narrow gap between the two cylindrical lenses. The results of laser-beam-transmission experiments indicate that, even at θ= 3.4° where almost no ions pass through the gap without interacting with the cylindrical glass surfaces, approximately 10% of the ions are transmitted. The transmission probability is asymmetric with respect to the polarity of θ, indicating that the ion beam impinging on the concave surface is more easily transmitted than when impinging on the convex surface. Furthermore, no significant ion-energy loss occurs upon transmission for the angular range -3≤θ≤+ 3.4°. These results provide evidence that fast heavy-ion beams are guided by curved surfaces.

Fluence enhancement of a 4 MeV-C4+ ion beam transmitted through a cylindrical glass channel after charging

“…This nonuniformity of the number density is attributed to the asymmetric shape of the CGC. Similar asymmetric behaviors were also exhibited by the transmission probability as functions of the tilt angle 42) and observation angle 43) of the incidence of the 4 MeV-C + and -C 4+ ion beams into the CGC. Furthermore, the deflection to the positive x direction (Fig.…”

“…The details of the CGC are described elsewhere, 42,43) nonetheless, we have provided a brief explanation herein. The structure of the CGC is schematically shown in Fig.…”

“…To solve this issue, we developed a cylindrical glass channel (CGC) 42) to replace the tapered glass capillary. The CGC comprises a pair of cylindrical convex and cylindrical concave glasses, positioned facing each other with a narrow gap; consequently, choosing the shape and the surface material becomes easy.…”

Guiding of 4 MeV C+ and C4+ ion beams using cylindrical glass channel

“…To clarify the ion-surface interaction at the inner walls of capillaries, in a previous work, the transmission properties of 4 MeV C + ions entering a curved glass channel were experimentally investigated. 31) Because the glass channel is formed by a convex cylindrical glass lens facing a concave cylindrical glass lens, we can adjust its curvature, gap distance, and material conditions (e.g., electric conductivity, roughness, composition, and structure). One of the biggest advantages of this method is that it allows for a wide choice of inner-wall surfaces for systematic measurements.…”

“…Actually, for |θ| > 3°with respect to the ion-beam axis, our previous study showed that ion scattering from the concave surface results in higher transmission than that from the convex surface. 31) The charge state of incident ions is an essential consideration for guiding keV HCIs. [1][2][3][4][5][6][7] Actually, Stolterfoht et al found a significant broadening of the angular profile of 3 keV Ne 7+ ions guided through nanocapillaries compared with 1 keV H 2 + ions, after a sufficiently large amount of charge was deposited on the surface.…”