Electrostatic end-field defocusing of neutral atoms and its compensation
Neutral atoms entering an electric field experience a defocusing force in the dipole field direction, which is proportional to the field gradient. If an experiment, such as the search for a permanent electron electric dipole moment (eEDM), requires a very strong electric field (13.5 MV/m), then thi...
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| Format: | Article |
| Language: | English |
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American Physical Society
2011-10-01
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| Series: | Physical Review Special Topics. Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevSTAB.14.104201 |
| _version_ | 1818026291911196672 |
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| author | Juris G. Kalnins |
| author_facet | Juris G. Kalnins |
| author_sort | Juris G. Kalnins |
| collection | DOAJ |
| description | Neutral atoms entering an electric field experience a defocusing force in the dipole field direction, which is proportional to the field gradient. If an experiment, such as the search for a permanent electron electric dipole moment (eEDM), requires a very strong electric field (13.5 MV/m), then this end-field defocusing results in beam blowup and much reduced phase-space acceptance. In this paper we discuss how these defocusing fields arise from the longitudinal changes in the electric dipole field and their dependence on the electrode shape and spacing between lenses. We find that the end-field defocusing comes from strong impulse forces, whose defocusing power was calculated for simple electrodes with rounded ends. To compensate for this end-field defocusing, a triplet of transverse-focusing lenses was added to the pure dipole field plates in the generic eEDM cesium fountain experiment used to study the neutral beam optics. Envelope equations, which calculated the beam sizes of the atom bunch for the linear forces, are used to obtain a set of lens parameters that give a well focused beam in the fountain. Atom trajectory equations allow us to calculate the phase-space acceptance of the lens system with the nonlinear force terms included. |
| first_indexed | 2024-12-10T04:29:41Z |
| format | Article |
| id | doaj.art-bb758c523d354c1ab7e0f2607d5a74a3 |
| institution | Directory Open Access Journal |
| issn | 1098-4402 |
| language | English |
| last_indexed | 2024-12-10T04:29:41Z |
| publishDate | 2011-10-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Special Topics. Accelerators and Beams |
| spelling | doaj.art-bb758c523d354c1ab7e0f2607d5a74a32022-12-22T02:02:11ZengAmerican Physical SocietyPhysical Review Special Topics. Accelerators and Beams1098-44022011-10-01141010420110.1103/PhysRevSTAB.14.104201Electrostatic end-field defocusing of neutral atoms and its compensationJuris G. KalninsNeutral atoms entering an electric field experience a defocusing force in the dipole field direction, which is proportional to the field gradient. If an experiment, such as the search for a permanent electron electric dipole moment (eEDM), requires a very strong electric field (13.5 MV/m), then this end-field defocusing results in beam blowup and much reduced phase-space acceptance. In this paper we discuss how these defocusing fields arise from the longitudinal changes in the electric dipole field and their dependence on the electrode shape and spacing between lenses. We find that the end-field defocusing comes from strong impulse forces, whose defocusing power was calculated for simple electrodes with rounded ends. To compensate for this end-field defocusing, a triplet of transverse-focusing lenses was added to the pure dipole field plates in the generic eEDM cesium fountain experiment used to study the neutral beam optics. Envelope equations, which calculated the beam sizes of the atom bunch for the linear forces, are used to obtain a set of lens parameters that give a well focused beam in the fountain. Atom trajectory equations allow us to calculate the phase-space acceptance of the lens system with the nonlinear force terms included.http://doi.org/10.1103/PhysRevSTAB.14.104201 |
| spellingShingle | Juris G. Kalnins Electrostatic end-field defocusing of neutral atoms and its compensation Physical Review Special Topics. Accelerators and Beams |
| title | Electrostatic end-field defocusing of neutral atoms and its compensation |
| title_full | Electrostatic end-field defocusing of neutral atoms and its compensation |
| title_fullStr | Electrostatic end-field defocusing of neutral atoms and its compensation |
| title_full_unstemmed | Electrostatic end-field defocusing of neutral atoms and its compensation |
| title_short | Electrostatic end-field defocusing of neutral atoms and its compensation |
| title_sort | electrostatic end field defocusing of neutral atoms and its compensation |
| url | http://doi.org/10.1103/PhysRevSTAB.14.104201 |
| work_keys_str_mv | AT jurisgkalnins electrostaticendfielddefocusingofneutralatomsanditscompensation |