Sasha GilevichDrive Laser Meeting December Launch System Outline General Layout Incidence Angle Effect of the broad bandwidth Adjustment of the beam diameter

Sasha GilevichDrive Laser Meeting December Launch System Layout (downstream from the shaper) Lens is attached to the cathode window Aperture in front of the grating allows to adjust the beam diameter on the cathode Second aperture after the grating corrects the ellipticity Grating 3600g/mm. Incidence angle at the cathode degrees Beam Shaper Aperture Grating Lens F=475mm Beamsplitter (for virtual Cathode Diagnostics) Lens F=150mm Window Cathode Aperture (grating) is imaged to the cathode plane 3:1

Sasha GilevichDrive Laser Meeting December Launch System Beam at the cathode Bandwidth =3nm First aperture R=3.95mm Second aperture R>4mm Efficiency=99.9% Spectrum was modeled as 21 wavelengths from 253.5nm to 256.5nm with the same weight

Sasha GilevichDrive Laser Meeting December Launch System Illumination on the cathode λ = 253.5nm λ = 255nm λ = 256.5nm

Sasha GilevichDrive Laser Meeting December Launch System Incidence Angle Issues For the off shelf grating (3600g/mm) and λ=255nm incidence angle at the cathode is 66.6 degrees The angle could be changed by changing the incidence angle on the grating Increasing of the incidence angle at the cathode will increase anamorphism. (see Tech note, written by Paul Bolton). This effect is more significant for the broad spectrum Change in the time slew is insignificant Mechanical Issues

Sasha GilevichDrive Laser Meeting December Launch System Adjustment of the beam diameter by closing of the first aperture First Aperture R=2.5mm Second Aperture R >4mm Efficiency=58.5%

Sasha GilevichDrive Laser Meeting December Launch System Illumination on the cathode (1 apertures) λ = 255nm λ = 256.5nm λ = 253.5nm

Sasha GilevichDrive Laser Meeting December Launch System Correction of the spatial beam shape with the second aperture First Aperture R=2.5mm Second Aperture R=3.5mm Tilt X=70 0 Decenter Y=-0.2mm Beam shaper decentered Y=0.04mm Efficiency=56%

Sasha GilevichDrive Laser Meeting December Launch System Illumination on the cathode (2 apertures) λ = 253.5nm λ = 255nm λ = 256.5nm λ = 253.5nm

Sasha GilevichDrive Laser Meeting December Launch System Bandwidth 4nm First aperture R=3.9mm Second aperture R>4mm Efficiency=99.7%

Sasha GilevichDrive Laser Meeting December Launch System Size of the input window For 3nm bandwidth the beam size on the window is about 3 x 12 mm Window diameter should exceed 20mm In case of broader spectrum and larger beam size it should be larger

Sasha GilevichDrive Laser Meeting December Launch System Adjustment of the beam diameter on the cathode Adjustment of the input aperture size It is possible in the small range Power loss Anamorphism Remotely adjustable iris is not available Zoom Telescope Complicated system, contains additional optics Expensive Takes more space Insertion of the fixed telescope Positive – positive telescope can image the output of the shaper to the grating, but has internal focus and requires more space Positive – negative telescope can cause the distortion of the spatial pulse shape

Sasha GilevichDrive Laser Meeting December Launch System Beam Radius = 0.4mm Telescope inserted in front of the first aperture ( and N distance 92mm) telescope

Sasha GilevichDrive Laser Meeting December Launch System Beam at the cathode Layout with the telescope. Bandwidth =3nm Without Apertures 15%

Sasha GilevichDrive Laser Meeting December Launch System Adjustment of the beam diameter by closing of the first aperture First Aperture R=1.1mm Second Aperture R >4mm Efficiency=82%

Sasha GilevichDrive Laser Meeting December Launch System Trim Aperture adjustment The similar set in the X-plane

Sasha GilevichDrive Laser Meeting December Launch System Correction of the spatial beam shape with the second trim aperture set First Aperture R=1.1mm Top Aperture Decenter -1.75mm Bottom Aperture Decenter +1.6mm Left and Right Aperture Decenter Y=+/-1.44mm Efficiency=77.4% 9%

Sasha GilevichDrive Laser Meeting December Launch System Relative Illumination on the Cathode Telescope, 2 Apertures

Sasha GilevichDrive Laser Meeting December Launch System Issues to be resolved Specify the incident angle at the cathode Check whether the mechanical dimensions of the cathode assembly, including window, are consistent with the proposed optical design Evaluate the spatial pulse shapes achievable with the proposed design. Will it allow to meet the e-specs? Specify the requirements to the beam diameter on the cathode. Is the continuous adjustment needed? Will the discrete adjustment proposed in this design work? Which adjustments should be done remotely? Scanning over the cathode. Requirements to the beam diameter and beam shape

Sasha GilevichDrive Laser Meeting December Launch System Unresolved Issue How does the imaging affect the temporal pulse shape?