High conversion efficiency and small spot size of Kα X-ray generated from nano-foam Cu targets irradiated by femtosecond laser pulses

Wang, Hongjian; Li, Zeren; Chen, Zhan-Bin

doi:10.1007/s00340-018-7039-1

Cited by 10 publications

(11 citation statements)

References 40 publications

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“…Thus, these experimental results suggest that the hot electron penetration depth is less than 4 µm. Note also that for the foil targets, we further checked if these results could not be explained by the refluxing effect at the target rear surface 8 . For inhibiting this effect, we set a SiO 2 substrate placed behind and in close contact with the Mo foils.…”

Section: Resultsmentioning

confidence: 99%

“…Laser-plasma hard x-ray sources are a suitable alternative to conventional accelerator-based x-ray sources of high brightness 1 , 2 and for applications requiring a high x-ray flux and a micrometric size such as x-ray phase contrast imaging 3 , 4 . Their characteristics and operating capabilities have been improved for decades 5 – 8 especially thanks to the continuous progress of femtosecond lasers in terms of intensity, spatial and temporal beam quality, repetition rate, reliability and compactness. In particular, such x-ray sources of ultrashort pulse duration driven by femtosecond laser systems offer an intrinsic synchronization for pump and probe experiments like time-resolved x-ray diffraction 9 and time-resolved x-ray absorption spectroscopy 10 .…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

Gambari

Clady

Videau

et al. 2021

Sci Rep

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The size of a hard Kα x-ray source ($${\mathrm{E}}_{{\rm{K}}_{\rm{\alpha }}}$$ E K α = 17.48 keV) produced by a high intensity femtosecond laser interacting with a solid molybdenum target is experimentally investigated for a wide range of laser intensity (I ~ 1017–2.8 × 1019 W/cm2) and for four values of the temporal contrast ratio (6.7 × 107 < CR < 3.3 × 1010). Results point out the size enlargement of the x-ray source with the increase of laser intensity and with the deterioration of temporal contrast. It amounts up to sixteen times the laser spot size at the highest laser intensity and for the lowest temporal contrast ratio. Using hydrodynamic simulations, we evaluate the density scale length of the pre-plasma L/λ just before the main pulse peak. This allows us to show that a direct correlation with the laser absorption mechanisms is not relevant to explain the large size broadening. By varying the thickness of the molybdenum target down to 4 µm, the impact of hot electron scattering inside the solid is also proved irrelevant to explain the evolution of both the x-ray source size and the Kα photon number. We deduce that the most probable mechanism yielding to the broadening of the source size is linked to the creation of surface electromagnetic fields which confine the hot electrons at the solid surface. This assumption is supported by dedicated experiments where the evolution of the size enlargement of the x-ray source is carefully studied as a function of the laser focal spot size for the highest contrast ratio.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

Gambari

Clady

Videau

et al. 2021

Sci Rep

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“…The CE of the femtosecond laser energy to Kα X-ray photons was calculated, including the intermediate process of converting electrons based on the number of photons recorded by LCX CCD. 24 , 25 It is acknowledged that there is a small deviation in the manufacturing accuracy of the detection instrument and the experimental measurement methods, so every experiment has a certain degree of cumulative error.…”

Section: Results and Discussionmentioning

confidence: 99%

“…In addition, the spot measured by the pinhole imaging method was slightly larger than the knife-edge method, while the spot measured with the knife-edge was 47 and 59 μm from laser-creased Cu foil, respectively. 25 In addition to the different incidence angles, the fs laser energy interaction with the nanowire material was also stronger, with more output and more focus. It might also be obliquely incident on the target surface, but the spot image looked elliptical.…”

Section: Results and Discussionmentioning

confidence: 99%

Kα X-ray Emission from Nanowire Cu Targets Driven by Femtosecond Laser Pulses for X-ray Conversion and Backlight Imaging

Wang

Chen

2020

ACS Omega

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A high-quality X-ray source was proposed by modifying the target material structure characteristics driven by ultrahigh laser energy. The experiments were performed on the Ti:sapphire femtosecond laser beam device (4.3–6 J, 30 fs), one of the three XG-III lasers in Laser Fusion Research Center of China Academy of Engineering Physics. The femtosecond laser beam drove the nanowire copper material with an average length of 18–50 μm and a diameter of about 260 nm. A single-photon counting charge-coupled device was employed to measure the copper Kα X-ray emission of the nanowire and foil targets. A clear maximum photon yield of the nanowire target was calculated to be 3.6 × 10 8 photons sr –1 s –1 , the conversion efficiency was up to 0.0087%, and the average yield was 2.5 times that of the copper foil targets. In addition, by using a pinhole imaging method of φ10 μm, the minimum full width at half maximum spot size of the X-ray source was calculated in the range of 85–240 μm, which was similar to that of the copper foil material with a long radius of 170 μm and a short radius of 63 μm. The experimental data illustrate that the nanowire has the potential to enhance the energy absorption of femtosecond laser for X-ray conversion and backlight imaging.

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“…На рис. 6 приведена сводная информация по выходу характеристического рентгеновского излучения в зависимости от интенсивности лазерного излучения (взята из работ [10][11][12][13][14][15][16][17] для вакуумных условий и длительности импульса 50−250 fs). На рисунке также приведен выход фотонов (серый квадрат), полученный в настоящем эксперименте при длительности импульса 300 fs.…”

Section: экспериментальны результатыunclassified

Эффективная Генерация Характеристического Рентгеновского Излучения При Воздействии Чирпированных Фемтосекундных Лазерных Импульсов На Медную Мишень При Локальном Поддуве Гелия

Garmatina¹,

Nazarov²,

Shcheglov³

et al. 2022

Оптика И Спектроскопия

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High conversion efficiency and small spot size of Kα X-ray generated from nano-foam Cu targets irradiated by femtosecond laser pulses

Cited by 10 publications

References 40 publications

Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

Kα X-ray Emission from Nanowire Cu Targets Driven by Femtosecond Laser Pulses for X-ray Conversion and Backlight Imaging

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