Angular Dependence of Copper Surface Damage Induced by an Intense Coherent THz Radiation Beam

Salvatore Macis,Akinori Irizawa,Stefano Lupi,Luca Tomarchio,S Javad Rezvani,Augusto Marcelli,Luigi Faillace,Silvia Tofani

doi:10.3390/condmat5010016

Abstract

In this work, we show the damage induced by an intense coherent terahertz (THz) beam on copper surfaces. The metallic surface was irradiated by multiple picosecond THz pulses generated by the Free Electron Laser (FEL) at the ISIR facility of the Osaka University, reaching an electric field on the sample surface up to ~4 GV/m. No damage occurs at normal incidence, while images and spectroscopic analysis of the surface point out a clear dependence of the damage on the incidence angle, the electric field intensity, and polarization of the pulsed THz radiation. Ab initio analysis shows that the damage at high incidence angles could be related to the increase of the absorbance, i.e., to the increase of the temperature around or above 1000 °C. The experimental approach we introduced with multiple fast irradiations represents a new powerful technique useful to test, in a reproducible way, the damage induced by an intense electric gradient on copper and other metallic surfaces in view of future THz-based compact particle accelerators.

Highlights

The damage induced by a strong EM field on metallic surfaces is a widely studied topic [1,2,3], where the aim is to understand the response of a material under strong applied electrical forces and the damage generated on the irradiated area
In this work, we show the damage induced by an intense coherent terahertz (THz) beam on copper surfaces
The experimental approach we introduced with multiple fast irradiations represents a new powerful technique useful to test, in a reproducible way, the damage induced by an intense electric gradient on copper and other metallic surfaces in view of future THz-based compact particle accelerators

Summary

Introduction

The damage induced by a strong EM field on metallic surfaces is a widely studied topic [1,2,3], where the aim is to understand the response of a material under strong applied electrical forces and the damage generated on the irradiated area. The THz electromagnetic spectral range, typically referred to frequencies between 100 GHz and 10 THz, is fundamental for the spectroscopic analysis of many condensed matter systems [10,11,12,13,14,15,16], low dimensional semiconductors and superconducting materials with different electronic properties [17,18,19,20]. This frequency range is, resonant with molecular and phonon excitations and with free electrons in metals [21].

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Conclusions