Highly localized ion focusing effects in PBIID

Abstract

Plasma Based Ion Implantation and Deposition (PBIID) is characterized by a complex interaction of a supersonic plasma flux, a plasma sheath expanding and receding on a timescale of microseconds and a substrate which can be of an arbitrary complex shape. It is shown that ions impinging on the substrate in the wake region consist of two groups with strongly differing incidence angles. At the same time, localized ion focusing is observed only for very long pulses of 50 µs and intermediate voltages of 2.5 – 3.5 kV, independent of the cathode material – Ti or Al – and the Ar background pressure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

In-field dependences of the critical current density J in GdBa2Cu3O7-d coated conductors produced by Zr irradiation and post-annealing at low temperatures

“…Irradiation with 6 MeV Zr +4 is expected to produce random point defects and nm-sized anisotropic defects. Previous irradiation studies of GBCO CCs showed that the optimal dosage to achieve the maximum pinning enhancement at temperatures below 40 K, using either H or O ions are 2×10 16 cm -2 and 1×10 14 cm -2 , respectively [5,7]. However, according to SRIM simulations, the Zr ions will produce significantly more displacements per collision than H or O.…”

“…Artificially designed mixed pinning landscapes seem to be a tool to improve critical current densities J c in high temperature superconductors [1,2,3]. A significant enhancement of the infield J c of RBa 2 Cu 3 O 7−δ (RBCO; R: Sm, Dy, Y, Gd) coated superconductors (CCs) can be obtained by adding pinning centers by ion irradiation [4,5,6,7,8]. For adequate irradiation fluences (which depend on mass and energy of ions), adding small clusters and random disorder assists the pinning produced by normal inclusions and twin boundaries (originated during the synthesis) [9,10].…”

“…The objective of this study is to find a correlation among the disorder produced by irradiation, the T c and the self-field and in-field dependence of J c . The pristine films display a pinning landscape with sphere-like and irregular precipitates (Gd 2 O 3 ) embedded in the GBCO matrix with typical diameter of approximately 50 nm [7]. In addition, correlated pinning produced by twin boundaries and boundaries between islands usually assists the pinning produced by the nanoparticles [13].…”