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Demonstration of self-truncated ionization injection for GeV electron beams.

Mirzaie M, Li S, Zeng M, Hafz NA, Chen M, Li GY, Zhu QJ, Liao H, Sokollik T, Liu F, Ma YY, Chen LM, Sheng ZM, Zhang J - Sci Rep (2015)

Bottom Line: Ionization-induced injection mechanism was introduced in 2010 to reduce the laser intensity threshold for controllable electron trapping in laser wakefield accelerators (LWFA).Subsequently, a dual-stage target separating the injection and acceleration processes was regarded as essential to achieve narrow energy-spread electron beams by ionization injection.Recently, we numerically proposed a self-truncation scenario of the ionization injection process based upon overshooting of the laser-focusing in plasma which can reduce the electron injection length down to a few hundred micrometers, leading to accelerated beams with extremely low energy-spread in a single-stage.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.

ABSTRACT
Ionization-induced injection mechanism was introduced in 2010 to reduce the laser intensity threshold for controllable electron trapping in laser wakefield accelerators (LWFA). However, usually it generates electron beams with continuous energy spectra. Subsequently, a dual-stage target separating the injection and acceleration processes was regarded as essential to achieve narrow energy-spread electron beams by ionization injection. Recently, we numerically proposed a self-truncation scenario of the ionization injection process based upon overshooting of the laser-focusing in plasma which can reduce the electron injection length down to a few hundred micrometers, leading to accelerated beams with extremely low energy-spread in a single-stage. Here, using 100 TW-class laser pulses we report experimental observations of this injection scenario in centimeter-long plasma leading to the generation of narrow energy-spread GeV electron beams, demonstrating its robustness and scalability. Compared with the self-injection and dual-stage schemes, the self-truncated ionization injection generates higher-quality electron beams at lower intensities and densities, and is therefore promising for practical applications.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the experimental setup.Up to 118 TW 30 fs laser pulses are focused down to 28 μm spot size with an OAP (f = 2 m) onto 4 mm or 1 cm supersonic gas jet of He and N2 gas mixture. The self-truncated ionization injection (STII) mechanism is illustrated in inset (a). Inset (b) shows a fixed fluorescent DRZ screen for monitoring the electron beam pointing and divergence angles before entering the magnet. Inset (c) is an electron beam energy spectrum. Top-view imaging system monitors the laser-plasma. ICT stands for integrating-current transformer used to measure the beam charge. The laser-produced plasma density was probed (not shown) in earlier experiments by the authors via interferometry using a 100 fs probe beam and by FRS diagnostic.
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f1: Schematic diagram of the experimental setup.Up to 118 TW 30 fs laser pulses are focused down to 28 μm spot size with an OAP (f = 2 m) onto 4 mm or 1 cm supersonic gas jet of He and N2 gas mixture. The self-truncated ionization injection (STII) mechanism is illustrated in inset (a). Inset (b) shows a fixed fluorescent DRZ screen for monitoring the electron beam pointing and divergence angles before entering the magnet. Inset (c) is an electron beam energy spectrum. Top-view imaging system monitors the laser-plasma. ICT stands for integrating-current transformer used to measure the beam charge. The laser-produced plasma density was probed (not shown) in earlier experiments by the authors via interferometry using a 100 fs probe beam and by FRS diagnostic.

Mentions: The reported experiments were conducted using a compact state-of-the art Ti: sapphire laser system at the Key Laboratory for Laser Plasmas of Shanghai Jiao Tong University. A schematic diagram of the experimental setup is shown in Fig. 1, more information are given in Methods section. In the following, the results are divided into two parts; in the first part we present results from 30 TW-level laser pulses while the results from above 100 TW-level laser pulses are presented in the second part.


Demonstration of self-truncated ionization injection for GeV electron beams.

Mirzaie M, Li S, Zeng M, Hafz NA, Chen M, Li GY, Zhu QJ, Liao H, Sokollik T, Liu F, Ma YY, Chen LM, Sheng ZM, Zhang J - Sci Rep (2015)

Schematic diagram of the experimental setup.Up to 118 TW 30 fs laser pulses are focused down to 28 μm spot size with an OAP (f = 2 m) onto 4 mm or 1 cm supersonic gas jet of He and N2 gas mixture. The self-truncated ionization injection (STII) mechanism is illustrated in inset (a). Inset (b) shows a fixed fluorescent DRZ screen for monitoring the electron beam pointing and divergence angles before entering the magnet. Inset (c) is an electron beam energy spectrum. Top-view imaging system monitors the laser-plasma. ICT stands for integrating-current transformer used to measure the beam charge. The laser-produced plasma density was probed (not shown) in earlier experiments by the authors via interferometry using a 100 fs probe beam and by FRS diagnostic.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4589762&req=5

f1: Schematic diagram of the experimental setup.Up to 118 TW 30 fs laser pulses are focused down to 28 μm spot size with an OAP (f = 2 m) onto 4 mm or 1 cm supersonic gas jet of He and N2 gas mixture. The self-truncated ionization injection (STII) mechanism is illustrated in inset (a). Inset (b) shows a fixed fluorescent DRZ screen for monitoring the electron beam pointing and divergence angles before entering the magnet. Inset (c) is an electron beam energy spectrum. Top-view imaging system monitors the laser-plasma. ICT stands for integrating-current transformer used to measure the beam charge. The laser-produced plasma density was probed (not shown) in earlier experiments by the authors via interferometry using a 100 fs probe beam and by FRS diagnostic.
Mentions: The reported experiments were conducted using a compact state-of-the art Ti: sapphire laser system at the Key Laboratory for Laser Plasmas of Shanghai Jiao Tong University. A schematic diagram of the experimental setup is shown in Fig. 1, more information are given in Methods section. In the following, the results are divided into two parts; in the first part we present results from 30 TW-level laser pulses while the results from above 100 TW-level laser pulses are presented in the second part.

Bottom Line: Ionization-induced injection mechanism was introduced in 2010 to reduce the laser intensity threshold for controllable electron trapping in laser wakefield accelerators (LWFA).Subsequently, a dual-stage target separating the injection and acceleration processes was regarded as essential to achieve narrow energy-spread electron beams by ionization injection.Recently, we numerically proposed a self-truncation scenario of the ionization injection process based upon overshooting of the laser-focusing in plasma which can reduce the electron injection length down to a few hundred micrometers, leading to accelerated beams with extremely low energy-spread in a single-stage.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.

ABSTRACT
Ionization-induced injection mechanism was introduced in 2010 to reduce the laser intensity threshold for controllable electron trapping in laser wakefield accelerators (LWFA). However, usually it generates electron beams with continuous energy spectra. Subsequently, a dual-stage target separating the injection and acceleration processes was regarded as essential to achieve narrow energy-spread electron beams by ionization injection. Recently, we numerically proposed a self-truncation scenario of the ionization injection process based upon overshooting of the laser-focusing in plasma which can reduce the electron injection length down to a few hundred micrometers, leading to accelerated beams with extremely low energy-spread in a single-stage. Here, using 100 TW-class laser pulses we report experimental observations of this injection scenario in centimeter-long plasma leading to the generation of narrow energy-spread GeV electron beams, demonstrating its robustness and scalability. Compared with the self-injection and dual-stage schemes, the self-truncated ionization injection generates higher-quality electron beams at lower intensities and densities, and is therefore promising for practical applications.

No MeSH data available.


Related in: MedlinePlus