Structural and Secondary Electron Yield Properties of Titanium-Palladium Films with Laser-Treated Copper Substrate for Application in Neutron Generators.

Yong Gao,Zhiming You,Yue Wu,Zhanglian Xu,Jiakun Fan,Yaocheng Hu,Qin Zhan,Hongguang Yang,Sheng Wang,Jing Zhang,Haipeng Li,Jie Wang

doi:10.3390/ma14051222

Yong Gao, Zhiming You + Show 10 more

Open Access

https://doi.org/10.3390/ma14051222

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Abstract

Secondary electron emission (SEE) of the oxygen-free high-conductivity copper (OFHC) target surface in neutron generators limits the stability and improvement of the neutron yield. A novel-type target of titanium–palladium films coated on laser-treated OFHC target substrate was proposed and explored in this work to obtain low secondary electron yield (SEY) without introducing any components. The combination of Ti–Pd films and laser-treated OFHC substrate can effectively suppress secondary electron emission and enhance the adsorption ability to hydrogen isotopes with the existence of Pd film. The surface morphologies, surface chemical states, and SEYs of Ti–Pd films with laser-treated OFHC substrate were studied systematically for the first time. The XPS results showed that the laser-treated OFHC substrate surface was basically covered by Pd film. However, the Pd film surface was partially oxidized, with percentages of 21.31 and 10.02% for PdO and PdO2, respectively. The SEYs of Ti–Pd films with laser-treated OFHC substrate were all below 1 within the investigated primary energy range of 100–3000 eV, which would be sufficient for application in neutron generators. Specifically, the maximum SEY (δmax) of laser-treated OFHC substrate coated by Ti–Pd films was 0.87 with corresponding incident electron energy of 400 eV.

Highlights

With the advantages of light weight, transportability, safety, and adjustable neutron yield, neutron generators have been widely used in oil logging [1], neutron activation analysis (NAA) [2,3], neutron radiography [4,5,6], and boron neutron capture therapy (BNCT) [7,8]
Platinum (Pt) film was coated onto the Ti and Ti–Pd films with untreated and laser-treated OHFC substrates before they were cut by a focused gallium ion beam to reduce the damage to film samples
A novel neutron generator target of Ti–Pd films coated on a lasertreated oxygen-free high-conductivity copper (OFHC) substrate was proposed

Summary

Introduction

With the advantages of light weight, transportability, safety, and adjustable neutron yield, neutron generators have been widely used in oil logging [1], neutron activation analysis (NAA) [2,3], neutron radiography [4,5,6], and boron neutron capture therapy (BNCT) [7,8]. Common neutron generators use 2 H(d,n) He (D–D) and 2 H(t,n) He (D–T). Fusion reactions to produce neutrons with energies of 2.5 and 14.1 MeV, respectively [9]. The solid target D–D reaction commercial neutron generator produced by Adelphi has the highest neutron yield of 5 × 109 n/s [10]. D–T reaction, the high neutron yield proposed and developed by Lanzhou University and Institute of Nuclear Energy Safety Technology [11,12] can reach to ~1012 n/s. The service lifetime of the neutron generator should be extended

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