Publications by authors named "Jeong Moon Yang"
The absolute response of a real-time proton detector, composed of a microchannel plate (MCP) assembly, an imaging lens, and a charge-coupled device (CCD) camera, is calibrated for the spectral characterization of laser-accelerated protons, using a Thomson parabola spectrometer (TPS). A slotted CR-39 plate was used as an absolute particle-counting detector in the TPS, simultaneously with the MCP-CCD detector to obtain a calibration factor (count/proton). In order to obtain the calibration factor as a function of proton energy for a wide range of proton numbers, the absolute response was investigated for different operation parameters of the MCP-CCD detector, such as MCP voltage, phosphor voltage, and CCD gain.
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- Researchers improved the performance of a 100-TW Ti:Sapphire laser by correcting wavefront distortions that occurred during the post-compression process, resulting in a greater intensity output.
- The laser's pulse duration was significantly reduced from 24 femtoseconds (fs) to 11 fs by using multiple fused silica plates and chirped mirrors.
- By implementing an adaptive optics system to fix wavefront aberrations, the quality of the laser beam was enhanced, increasing the Strehl ratio from 0.37 to 0.52 and enhancing the focused intensity by 1.5 times compared to just a 1.1 times enhancement without correction.
A localized nanoparticle insertion scheme is developed to decouple electron injection from laser evolution in laser wakefield acceleration. Here we report the experimental realization of a controllable electron injection by the nanoparticle insertion method into a plasma medium, where the injection position is localized within the short range of 100 μm. Nanoparticles were generated by the laser ablation process of a copper blade target using a 3-ns 532-nm laser pulse with fluence above 100 J/cm.
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- Researchers achieved pulse generation under 10 femtoseconds (fs) by enhancing peak power from a 100 TW Ti:Sapphire laser through post-compression.* -
- The process involved broadening the laser spectrum using self-phase modulation in thin fused silica plates and compensating for the spectral phase with chirped mirrors.* -
- A spatial filter setup with lenses helped reduce intensity spikes, ultimately compressing the laser pulse from 23 fs to 9.7 fs, resulting in a 2.1 times increase in peak power.*
We present a proof of principle for onsite calibration of a radiochromic film (EBT3) using CR-39 as an absolute proton-counting detector and laser-accelerated protons as a calibration source. A special detector assembly composed of aluminum range filters, an EBT3 film, and a CR-39 detector is used to expose the EBT3 film with protons in an energy range of 3.65 MeV-5.
View Article and Find Full Text PDFWe demonstrated the generation of 4.2 PW laser pulses at 0.1 Hz from a chirped-pulse amplification Ti:sapphire laser.
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