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Proton Bunch Self-Modulation in Plasma with Density Gradient
F Braunmüller1, T Nechaeva2, E Adli3
1Max Planck Institute for Physics, Munich, Germany.
Physical Review Letters
|January 15, 2021
Summary
Plasma density gradients significantly alter proton bunch self-modulation. Increasing or decreasing gradients modify microbunch formation and modulation frequency, impacting particle acceleration research.
Area of Science:
- Plasma Physics
- Particle Accelerators
Background:
- Proton bunch self-modulation is crucial for advanced particle acceleration techniques.
- Understanding plasma density effects is key to controlling beam dynamics.
Purpose of the Study:
- To experimentally investigate the impact of linear plasma density gradients on proton bunch self-modulation.
- To analyze changes in microbunch characteristics and modulation frequencies.
Main Methods:
- Experimental study of a 400 GeV proton bunch.
- Propagation through a 10-meter plasma with controlled linear density gradients.
- Analysis of microbunch formation, charge distribution, and modulation frequencies.
Main Results:
- Positive and negative plasma density gradients alter microbunch number and relative charge.
- Modulation frequency directly correlates with gradient direction (positive/negative).
- Observed two distinct modulation frequencies under the largest positive gradient.
Conclusions:
- Plasma density gradients influence wakefield phase velocity, affecting self-modulation growth.
- Experimental results align with theoretical predictions of gradient-enhanced wakefields.
- Control over plasma gradients offers a method to tailor proton bunch behavior.
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