Technological aspects of Electron Lenses, errors and control Vsevolod Kamerdzhiev for Fermilab...
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![Page 1: Technological aspects of Electron Lenses, errors and control Vsevolod Kamerdzhiev for Fermilab Beam-Beam Compensation team LARP Mini-Workshop on Beam-Beam.](https://reader038.fdocuments.in/reader038/viewer/2022102818/56649d4b5503460f94a28045/html5/thumbnails/1.jpg)
Technological aspects of Electron Lenses, errors and control
Vsevolod Kamerdzhievfor Fermilab Beam-Beam Compensation team
LARP Mini-Workshop on Beam-Beam Compensation, July 2-4, 2007
![Page 2: Technological aspects of Electron Lenses, errors and control Vsevolod Kamerdzhiev for Fermilab Beam-Beam Compensation team LARP Mini-Workshop on Beam-Beam.](https://reader038.fdocuments.in/reader038/viewer/2022102818/56649d4b5503460f94a28045/html5/thumbnails/2.jpg)
V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 2
Tevatron Electron Lenses
TEL2
The TEL2 magnetic system consists of eight conventional solenoids, the 65 kG SC main solenoid, four short 8 kG and two long 2 kG SC dipole correctors.
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 3
Magnetic field measurements
•Short corrector 1, I = 191.42 A
•0
•0.5
•1
•1.5
•2
•2.5
•3
•3.5
•4
•4.5
•5
•5.5
•6
•-350 •-300 •-250 •-200 •-150 •-100 •-50 •0 •50 •100 •150 •200 •250 •300 •350•Longitudinal pozition z, mm
• Ma
gn
eti
c f
ield
, k
G
Magnetic field quality along the electron beam path has been verified using 3D Hall probe
in addition, a laser based technique was used to check the straightness of magnetic field lines in the main solenoid (<100 m).
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 4
Electron gun
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 5
Using the tube based modulator
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 6
First TEL2 e-beam
Cathode current
Collector current
Modulator grid
Trigger pulse
Was improved to better than 5%
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 7
TEL1 e-current ripple
0.4 Hz15 Hz
~1% variation
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 8
Using the Marx generator
![Page 9: Technological aspects of Electron Lenses, errors and control Vsevolod Kamerdzhiev for Fermilab Beam-Beam Compensation team LARP Mini-Workshop on Beam-Beam.](https://reader038.fdocuments.in/reader038/viewer/2022102818/56649d4b5503460f94a28045/html5/thumbnails/9.jpg)
V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 9
Modulator vs Marx generator
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Marx generator
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TEL2 in pulsed mode (Marx)
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TEL2 e-current ripple, timing jitter
60 Hz<1 %
cure found
fixed< 1ns now
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Marx generator failure
Schottky power
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Emittance growth vs e-beam noise
TEL2Δ
ε/Δ
t
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 15
Emittance growth vs e-beam noise
TEL1
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 17
The e-beam world
gun
collector
BPMs
Isolated electrodes
L-shaped pickup
Reliable position measurement for all tree beams is challenging due to very different spectral content. Currently we can achieve ~100 m accuracy/resolution
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 18
Summary
The e-beam quality in both TELs reached the level that made reproducible demonstration of beam-beam compensation possible.
Generating dc e-beam does not appear very challenging, however generating pulsed beam (individual compensation of all bunches) does.
Though the voltage itself is not a challenge – short rise time and high rep rate requirements make the development of the e-gun driver very challenging.
The solid state Marx generator proved to be a reliable electron gun driver (with radiation shielding installed).
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V. Kamerdzhiev for BBC team Technological aspects of Electron Lenses, errors and control 19
Plans
• Further reduce e-beam noise and ripple
• Simulate the effects of e-beam noise, ripple on beam lifetime and emittance growth (Lifetrac)
• Upgrade HV pulse generators (second generation Marx and solid-state modulator based on a summed pulse transformer scheme), multi-bunch BBCompensation
• Install gaussian electron guns and perform head-on compensation studies (dc or pulsed)
• Study the effect of electron beam size on protons (lifetime, halo, Schottky) in both TELs
• Improve position measurement