Femtosecond laser-induced damage threshold in snow micro-structured targets

Abstract

Enhanced acceleration of protons to high energy by relatively modest high power ultra-short laser pulses, interacting with snow micro-structured targets was recently proposed. A notably increased proton energy was attributed to a combination of several mechanisms such as localized enhancement of the laser field intensity near the tip of $1~\unicode[STIX]{x03BC}\text{m}$ size whisker and increase in the hot electron concentration near the tip. Moreover, the use of mass-limited target prevents undesirable spread of absorbed laser energy out of the interaction zone. With increasing laser intensity a Coulomb explosion of the positively charged whisker will occur. All these mechanisms are functions of the local density profile and strongly depend on the laser pre-pulse structure. To clarify the effect of the pre-pulse on the state of the snow micro-structured target at the time of interaction with the main pulse, we measured the optical damage threshold (ODT) of the snow targets. ODT of $0.4~\text{J}/\text{cm}^{2}$ was measured by irradiating snow micro-structured targets with 50 fs duration pulses of Ti:Sapphire laser.

Monoenergetic proton beam accelerated by single reflection mechanism only during hole-boring stage

“…In the future, the development of 10 PW, and even 100 PW, laser systems [43–46] , and target fabrication [47, 48] could lead to reaching laser intensities of the order of , which can easily accelerate the proton layer to energies of hundreds of MeV (refer to Figure 5). For example, protons can be generated by a , 250 J laser ( energy in a focal spot (FWHM), corresponding to a laser intensity of ) irradiating the multilayer foil (areal density ).…”

Facilities in Asia for future accelerator development

“…An optical guiding scheme is proposed and tested to conquer the limited length of the interaction that must be solved in high-energy laser wakefield acceleration. In particular, novel targets such as snow clusters [51] are investigated to enhance the absorption of the laser energy in the target to produce a large number of X-rays [52].…”

High Refractive Index Metamaterials by Using Higher Order Modes Resonances of Hollow Cylindrical Nanostructure in Visible Region

“…The artificially engineering metamaterials have been developed to realize the desired materials which are not obtained in naturally materials [1]- [4]. The effective refractive indices in metamaterials can be tunable by critically design of artificial atoms [5]- [7]. It is known that the negative refractive index metamaterials [8]- [11] and near-zero index metamaterials [12], [13] have been extensively studied in last dozen years.…”