Free electron lasers driven by plasma accelerators: status and near-term prospects

Abstract

Owing to their ultra-high accelerating gradients, combined with injection inside micrometer-scale accelerating wakefield buckets, plasma-based accelerators hold great potential to drive a new generation of free-electron lasers (FELs). Indeed, the first demonstration of plasma-driven FEL gain was reported recently, representing a major milestone for the field. Several groups around the world are pursuing these novel light sources, with methodology varying in the use of wakefield driver (laser-driven or beam-driven), plasma structure, phase-space manipulation, beamline design, and undulator technology, among others. This paper presents our best attempt to provide a comprehensive overview of the global community efforts towards plasma-based FEL research and development.

Attosecond-Angstrom free-electron-laser towards the cold beam limit

“…Ingenious post-plasma compensation approaches have been developed to address individual beam quality limitations, i.e. compensation of energy spread constraints or increasing peak current post-beam generation 16 – 26 , with efforts focused on working towards soft X-ray FEL demonstration 27 . The most advanced experimental success so far has been the recent demonstration of FEL gain in the EUV 28 and IR 29 range and seeded FEL 30 .…”

Measurement of electron beam transverse slice emittance using a focused beamline

“…From the early stage of tens of percent level energy spread and few mm mrad-level emittance, LWFA electron beams have now achieved electron beams with nC-level charge [4,5], few per-mille level relative energy spread [6][7][8][9], and sub-mm mrad-level emittance [10]. Benefitted from the ultrahigh acceleration gradient of LWFA [11][12][13][14][15], ultra-compact radiation sources, such as Betatron radiation [16][17][18], Compton scattering [19][20][21][22] and tabletop free electron lasers (FELs) [23][24][25],…”

“…From the early stage of tens of percent level energy spread and few mm mrad-level emittance, LWFA electron beams have now achieved electron beams with nC-level charge [ 4 , 5 ] , few per-mille-level relative energy spread [ 6 – 9 ] and sub-mm mrad-level emittance [ 10 ] . Benefitted from the ultra-high acceleration gradient of LWFA [ 11 – 15 ] , ultra-compact radiation sources, such as betatron radiation [ 16 – 18 ] , Compton scattering [ 19 – 22 ] and tabletop free electron lasers (FELs) [ 23 – 25 ] , injectors for future colliders [ 26 ] will be possible. Most LWFA-based applications require an excellent 6D electron beam brightness [ 27 , 28 ] , defined by , where is the peak current, is the relative energy spread and and are the normalized transverse emittance of the electron beam.…”

“…From the early stage of tens of percent level energy spread and few mm mrad-level emittance, LWFA electron beams have now achieved electron beams with nC-level charge [4,5] , few per-mille-level relative energy spread [6][7][8][9] and sub-mm mrad-level emittance [10] . Benefitted from the ultra-high acceleration gradient of LWFA [11][12][13][14][15] , ultracompact radiation sources, such as betatron radiation [16][17][18] , Compton scattering [19][20][21][22] and tabletop free electron lasers (FELs) [23][24][25] , injectors for future colliders [26] will be possible. Most LWFA-based applications require an excellent 6D electron beam brightness [27,28] , defined by B 6D = I P ε nx ε ny σ γ •0.1% , where I P is the peak current, σ γ is the relative energy spread and ε nx and ε ny are the normalized Correspondence to: Ke Feng, Wentao Wang, and Ruxin Li, State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.…”

Attosecond-Angstrom free-electron-laser towards the cold beam limit

“…Ingenious post-plasma compensation approaches have been developed to address individual beam quality limitations, i.e. compensation of energy spread constraints, or increasing peak current post beam generation 16,17,18,19,20,21,22,23,24,25,26 , with efforts focused working towards soft X-ray FEL demonstration 27 . The most advanced experimental success so far has been the recent demonstration of FEL gain in the EUV 28 and IR 29 range.…”