Performance Enhancement of Laser Wakefield Electron Accelerators Based on Shock-Front Injection

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/97744

Title:	Performance Enhancement of Laser Wakefield Electron Accelerators Based on Shock-Front Injection
Authors:	王志嘉;Wang, Jhih-Jia
Contributors:	物理學系
Keywords:	雷射尾波場加速器;震波前注入法;laser wakefield acceleration;shock-front injection
Date:	2025-05-07
Issue Date:	2025-10-17 11:51:12 (UTC+8)
Publisher:	國立中央大學
Abstract:	震波前注入法為一項於雷射尾波場加速器中產生高品質、單一能量電子束的前沿技術。該技術可精確控制電子注入的時機與位置，從而實現極高穩定性的單一能量輸出。本研究於中央大學採用 100-TW 雷射進行電子加速實驗。藉由在氣體介質中置放刀片以攔截超音速氣流、形成震波前，再將強脈衝雷射聚焦於該區域，得以實現震波前注入法的電子加速。實驗中採用不同出口直徑的氣體射流噴嘴調控氣體分佈:在純氦氣實驗中，當噴嘴直徑由 3 mm 增加至 5 mm 時，電子束的單一能量峰值由 125 MeV 提升至 160 MeV，且電子電量亦由 5.2 pC 提升至 45 pC;加速梯度達 100 GeV/m，與雷射尾波場加速器的理論極限相符。此外，將氣體介質由純氦氣改為混合氣體(0.5% 氮氣與 99.5% 氦氣)後，注入機率由 20% 提升至 45%。以上結果充分驗證了震波前注入法在產生高品質、單一能量電子束方面的優勢與效能。 ;Shock-front injection is a promising technique for generating a high-quality, monoener- getic electron beam in laser wakefield acceleration (LWFA). It provides precise control over the injection timing and position, leading to a monoenergetic output with high stability. In this thesis, we use the 100-TW laser at National Central University to drive the elec- tron acceleration. By blocking a supersonic gas flow with a blade, we create a shock front in the gas medium. Then, by focusing the intense laser pulse in such a medium, electron acceleration with shock front injection is achieved. We use gas jet nozzles with different outlet diameters to control the gas medium distribution. In pure helium experiments, when the nozzle diameter is increased from 3 mm to 5 mm, the electron monoenergetic peak is increased from 125 MeV to 160 MeV, and the beam charge is also increased from 5.2 pC to 45 pC. The acceleration gradient reaches 100 GeV/m, consistent with the the- oretical limit of LWFA. Furthermore, by using a mixture gas of 0.5% N2 and 99.5% He instead of pure helium, the injection probability is increased from 20% to 45%. These achievements demonstrate the advantages and effectiveness of the shock-front injection technique.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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