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Harmonic Lasing for LCLS-II?

Harmonic Lasing for LCLS-II?. Z. Huang 11/10/2013. Motivation. LCLS HXR 5 keV barely reaches saturation at 150 m. V ery small K (= 0.59) is a main problem Harmonic lasing 1 overcomes this problem by running fundamental wavelength at a much larger K

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Harmonic Lasing for LCLS-II?

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  1. Harmonic Lasing for LCLS-II? Z. Huang 11/10/2013

  2. Motivation • LCLS HXR 5 keV barely reaches saturation at 150 m. Very small K (= 0.59) is a main problem • Harmonic lasing1overcomes this problem by running fundamental wavelength at a much larger K • 3D theory shows a fundamental gain length at 5 keV is 5.5 m, while harmonic theory2 yields a 3rd harmonic gain length of 3.3 m at 5 keV • In case that HXR line is removed for cost reasons, SXR line can reach at least 3 times photon energy Schneidmillerand Yurkov, PRSTAB 15, 080702 (2012). Huang and Kim, PRE 62, 7295 (2000).

  3. HXR at 5 keV • 4 GeV, 1 kA, 0.4 µm emittance, 500 keV E-spread From Y. Ding Fundamental at 5 keV lu=2.6 cm, K=0.59

  4. HXR at 5 keV • Retune K = 2.25, adjust phase shifters to suppress fundamental at 1.66 keV • 3rd harmonic lases at 5 keV and saturates around 70 m 3rd harmonic at 5 keV Fundamental at 1.66 keV lu=2.6 cm, K=2.25 Steady State simulations so far.SASE requires more elaborated phase shifter schemes (combinations of 2pi/3 and 4pi/3)

  5. SXR at 1.24 keV • 4 GeV, 1 kA, 0.4 µm emittance, 500 keV E-spread From G. Marcus Fundamental at 1.24 keV lu=3.9 cm, K=2.07

  6. SXR harmonic lasing (at 3.7 keV) • Same K (=2.07) but use phase shifters to disrupt fundamental at 1.24 keV 3rd harmonic at 3.7 keV Fundamental at 1.24 keV Steady State simulations so far.SASE requires more elaborated phase shifter schemes (combinations of 2pi/3 and 4pi/3)

  7. Discussions • SASE simulations are required to verify these preliminary steady state results (may see BW narrowed by a factor of ~3) • Harmonic lasing allows HXR to reach 5 keV (and more) with shorter saturation length, hence allows self-seeding at 5 keV • Harmonic lasing extends the wavelength reach of SXR. • In case HXR is cut from cost, SXR line may be lengthened to reach 5 keV with harmonic lasing • Phase shifters can be used in combinations with filters to suppress fundamental. A filtered harmonic lasing test is planned for LCLS (Ratner et al., FEL2013)

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