Outline
General Layout
Scanning over the Cathode
Adjustment of the beam diameter
Mechanical Issues (window size, angle of
incidence)
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Previous Layout
(downstream from the shaper)
Aperture (grating) is
imaged to the cathode
plane 3:1
Grating
Lens F=475mm
Aperture
Insertable
telescope (3:1)
decreases the
beam radius
Lens is attached to
the cathode window
Beamsplitter
(for virtual Cathode
Diagnostics)
Beam Shaper
Lens
F=150mm
Window
Cathode
Grating 3600g/mm. Incidence angle at
the cathode 66.63 degrees
January 13 2005
Launch System
Drive Laser Meeting
Aperture in front of
the grating allows to
adjust the beam
diameter on the
cathode
Second set of
apertures after the
grating corrects the
ellipticity
Sasha Gilevich
Gilevich@slac.stanford.edu
Disadvantages
Does not have scanning possibility
Does not allow continuous adjustment of the
beam diameter
Lens is attached to the cathode window
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Scanning
(by linear motion of 2 mirrors)
mirror
mirror
cathode
mirror
cathode
Incidence angle is
preserved
Allows independent
horizontal and vertical
adjustment
January 13 2005
Launch System
Drive Laser Meeting
Requires 3 mirrors between the
second lens and the cathode (path
length should be increased)
Could effect the image quality (can
be compensated by moving the lens)
Sasha Gilevich
Gilevich@slac.stanford.edu
Layout
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Adjustment of the Beam Diameter
Adjustment
Range:
2.5
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
0.3
Without
telescope:
250
200
150
100
80
130
Delay, mm
January 13 2005
Launch System
180
230
280
330
Distance L2-M6
Beam Radius, mm
Beam Size Adjustment
1.1 – 2.4
With telescope:
0.38 – 0.86
50
380
Rx @ 0.5
Rx @ 0.5 telescope
L2 - M6
L2 - M6 telescope
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Beam Profile
Delay length 360mm
Y
X
Side – 5mm
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Beam Profile
Delay length 85mm
Y
X
Side – 10mm
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Beam Profile with the Telescope
Delay length 90mm
Y
Y
X
X
Side – 5mm
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Beam Profile with the Telescope
Delay length 365mm
YY
X
X
Side – 2mm
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Gun Design
Beam Profile 44.73 from
the cathode
Size = 6x2.2
Beam Profile 44.73+18 from
the cathode
Size = 7.6x2.6
Side 10mm
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Mechanical Issues
Maximum beam size on the window –13mm.
Window should be about 20mm
Maximum beam size in the hole 8x3mm. The
hole should exceed 11x6mm (+some space for
alignment)
Incidence angle 67.5 degrees (22.5)
Design requires large optics
(3mm scanning)
(M11 diameter>90mm)
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu
Summary
Design allows to move the beam on the cathode
(requires 2 remotely controlled linear stages and, if the
beam quality is the issue, lens position adjustment)
Design allows to change the beam radius in the
range 2.4 – 1.15 and 0.86 – 0.38mm (beams with
R<0.4 have some distortion) (requires 2 remotely controlled
stages: delay length and lens position)
Design requires large optics (possibly custom
made mirrors)
January 13 2005
Launch System
Drive Laser Meeting
Sasha Gilevich
Gilevich@slac.stanford.edu