IPAC2022 - Table of Session: WEIZSP (Invited Orals: Beam Dynamics and EM Fields)

Paper	Title	Page
WEIZSP1	Interpretation of Particle Motion in a Circular Accelerator as Diffraction of Light
	T. Hiraiwa RIKEN SPring-8 Center, Hyogo, Japan
	Inspired by Fermat’s principle of geometric optics 200 years ago, famous Dr. Hamilton built Hamiltonian mechanics based on the principle of minimal action. Since then, optics and mechanics have developed while stimulating each other. A new hidden link between optics and mechanics was recently found on particle motion in a circular accelerator. A forced harmonic oscillator is often used as a model to describe particle motion in a circular accelerator. Such a model sometimes assumes that, eigen frequency or frequency of the external force is changed slowly with time to simulate, for example, resonance crossing, beam dump by turning off the RF power, resonance extraction, etc. in circular accelerators. In such cases, particle motion is well described by using formulae for Fresnel or Fraunhofer diffraction, depending on simulation conditions. This presentation will comprehensively show what is essential mechanism to link resonance phenomena of mechanics and optical diffraction, relation between the real accelerator model and the harmonic oscillator, and possibility of this knowledge to apply investigation of beam dynamics in a particle accelerator.
	Slides WEIZSP1 [5.755 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEIZSP2	Trapping of Neutral Molecules by the Electromagnetic Beam Field	1649
	G. Franchetti GSI, Darmstadt, Germany F. Zimmermann CERN, Meyrin, Switzerland
	Neutral uncharged molecules are affected by the electromagnetic field of a charged particle beam if they carry either an electric or a magnetic dipole moment. The residual gas in an accelerator beam pipe consists of such molecules. In this paper we study their dynamics. Under a few approximations, whose validity we explore and justify, we derive the equations of motion of neutral molecules and their invariants, determine the conditions for these neutral molecules to become trapped in the field of the beams as function of beam-pipe temperature, and compute the resulting enhancement of molecule density in the vicinity of the beam. We demonstrate that large agglomerates of molecules, "flakes," are much more likely to be pulled into the beam than single molecules, and suggest that this phenomenon might help explain some beam observations at the Large Hadron Collider.
	Slides WEIZSP2 [6.142 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIZSP2
About •	Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

WEIZSP1

Interpretation of Particle Motion in a Circular Accelerator as Diffraction of Light

T. Hiraiwa
RIKEN SPring-8 Center, Hyogo, Japan

Inspired by Fermat’s principle of geometric optics 200 years ago, famous Dr. Hamilton built Hamiltonian mechanics based on the principle of minimal action. Since then, optics and mechanics have developed while stimulating each other. A new hidden link between optics and mechanics was recently found on particle motion in a circular accelerator. A forced harmonic oscillator is often used as a model to describe particle motion in a circular accelerator. Such a model sometimes assumes that, eigen frequency or frequency of the external force is changed slowly with time to simulate, for example, resonance crossing, beam dump by turning off the RF power, resonance extraction, etc. in circular accelerators. In such cases, particle motion is well described by using formulae for Fresnel or Fraunhofer diffraction, depending on simulation conditions. This presentation will comprehensively show what is essential mechanism to link resonance phenomena of mechanics and optical diffraction, relation between the real accelerator model and the harmonic oscillator, and possibility of this knowledge to apply investigation of beam dynamics in a particle accelerator.

Slides WEIZSP1 [5.755 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEIZSP2

Trapping of Neutral Molecules by the Electromagnetic Beam Field

1649

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Meyrin, Switzerland

Neutral uncharged molecules are affected by the electromagnetic field of a charged particle beam if they carry either an electric or a magnetic dipole moment. The residual gas in an accelerator beam pipe consists of such molecules. In this paper we study their dynamics. Under a few approximations, whose validity we explore and justify, we derive the equations of motion of neutral molecules and their invariants, determine the conditions for these neutral molecules to become trapped in the field of the beams as function of beam-pipe temperature, and compute the resulting enhancement of molecule density in the vicinity of the beam. We demonstrate that large agglomerates of molecules, "flakes," are much more likely to be pulled into the beam than single molecules, and suggest that this phenomenon might help explain some beam observations at the Large Hadron Collider.

Slides WEIZSP2 [6.142 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIZSP2

About •

Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)