Transverse Laser Cooling of a Fast Stored Ion Beam through Dispersive Coupling

Lauer, I.; Eisenbarth, U.; Grieser, M.; Grimm, Rudolf; Lenisa, P.; Luger, V.; Schätz, T.; Schramm, U.; Schwalm, D.; Weidemüller, Matthias

doi:10.1103/physrevlett.81.2052

Cited by 53 publications

(24 citation statements)

References 18 publications

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“…would be strongly suppressed, and the beam heating by laser-induced diffusion could become dominant. The loss of transverse cooling would be more critical vertically, since the horizontal motion would still be cooled by dispersive cooling [4]. The observed decrease of the horizontal beam size after the blowup starts supports this hypothesis as the IBS calculation indicated heating (which before the blowup is countered by the dispersive cooling).…”

supporting

confidence: 71%

“…We argue that this low-current vertical blowup of the beam arises due to a sudden reduction of the indirect transverse cooling mediated by intrabeam scattering (IBS), which thus no longer compensates the diffusive heating caused by the spontaneous emission of photons during laser cooling. The horizontal dimension, however, is cooled by the dispersive coupling between the horizontal and the longitudinal dimensions [4] and thus does not blow up. Our results indicate that there may be serious limitations to the possibility of using laser cooling in the creation of a crystalline beam.…”

mentioning

confidence: 99%

“…Laser cooling is performed in one straight section, with copropagating and counterpropagating laser beams, having radii of ϳ3 mm, overlapping the ion beam. The overlap between the laser beams and the ion beam is carefully optimized for optimum longitudinal and transverse cooling [2,4]. For diagnostic purposes, copropagating laser light in a second ring section is focused and overlaps the ion beam in the post acceleration tube (PAT) in front of the transverse imaging system.…”

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Low-Current, Vertical Blowup in a Stored Laser-Cooled Ion Beam

et al. 2001

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Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents, we observe an abrupt change in this behavior: The vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser cooling. DOI: 10.1103/PhysRevLett.87.274801 PACS numbers: 29.20.Dh, 29.27.Bd, 42.50.Vk, 52.27.Jt Laser cooling in a storage ring [1] has been demonstrated to be a powerful tool for creating ultracold and dense stored ion beams [2]. Cold and dense beams are of interest for many storage ring applications, and the ultimate state for such beams is the attainment of ion beam crystallization [3].Using a novel technique for transverse beam profile diagnostics, we have studied the development of the transverse beam size of a stored, laser-cooled, low-current coasting ion beam in the ASTRID storage ring. Earlier we observed that the maximum density of a stored lasercooled ion beam is limited by the space charge tune shift [2]. In this Letter, we present experimental evidence of a deviation from this behavior at very low ion beam currents. During continuous observation of the transverse beam size of the stored beam, we observe how the beam size is reduced as the beam current decays due to charge exchange with the residual gas in the storage ring. At a certain point in time (and thus beam current), we observe that the vertical beam size increases dramatically, while at the same time the horizontal beam size decreases. The current at which this happens depends on the cooling power, the laser detuning, and the laser polarization. The circulating beam current at the time of this observation is below the maximum current at which a "string" (a onedimensional ordered beam [3]) may exist in the machine. We argue that this low-current vertical blowup of the beam arises due to a sudden reduction of the indirect transverse cooling mediated by intrabeam scattering (IBS), which thus no longer compensates the diffusive heating caused by the spontaneous emission of photons during laser cooling. The horizontal dimension, however, is cooled by the dispersive coupling between the horizontal and the longitudinal dimensions [4] and thus does not blow up. Our results indicate that there may be serious limitations to the possibility of using laser cooling in the creation of a crystalline beam. These observations have been made possible by the use of a novel technique for studying the transverse beam profile of a stored ion beam. By imaging the fluorescent light from the laser-excited ion beam onto a high resolution, image intensified, charge-coupled device (CCD) camera, we can directly monitor the beam profile in real time, and that with a much higher sensitiv...

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supporting

confidence: 71%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Low-Current, Vertical Blowup in a Stored Laser-Cooled Ion Beam

et al. 2001

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“…The powerful longitudinal cooling effect is effectively transferred through these coupling sources under the resonance conditions and we can thus expect efficient, indirect laser cooling in both transverse directions. Lauer et al have demonstrated another indirect transverse cooling scheme based on a dispersive transverse cooling force caused by horizontal displacement of a cooling laser [13]. This scheme, however, has a practical limitation that the laser power is not fully utilized for beam cooling because of a poor overlap between the laser and ions.…”

Section: Introductionmentioning

confidence: 99%

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Nakao

T.Hiromasa

Souda

et al. 2012

Phys. Rev. ST Accel. Beams

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We report the first observation of indirect resonantly enhanced transverse laser cooling of a bunched, stored ion beam of 40 keV 24 Mg þ . The longitudinal velocity distribution and the horizontal beam size of the laser-cooled 24 Mg þ ion beam with 280 nm laser light were simultaneously observed by the use of standard fluorescence-based techniques. Keeping the operation point at (2.068, 1.105), the synchrotron tune ( s ) was changed from 0.0376 to 0.1299. A strong decrease in the cooled horizontal beam size and a corresponding increase in the equilibrium cooled momentum spread were observed at the expected synchrobetatron resonance coupling condition of s ¼ 0:068, which is the first observation of a resonantly induced coupling for enhanced indirect transverse laser cooling of an ion beam, and is an important step towards creating a crystalline ground state of the beam.

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“…This offers great perspectives for future facilities that will provide high-quality stored ion beams for precision experiments. Laser cooling of stored coasting and bunched ion beams has been demonstrated at the TSR in Heidelberg (Germany) [2,3], and at ASTRID in Aarhus (Denmark) [4]. At the Experimental Storage Ring (ESR) in Darmstadt (Germany), first laser cooling experiments at moderately relativistic energies were conducted [5].…”

Section: Introductionmentioning

confidence: 99%

Cooling rates and intensity limitations for laser-cooled ions at relativistic energies

Eidam

Winters

2018

Nuclear Instruments and Methods in Physics Research Section A:

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The ability of laser cooling for relativistic ion beams is investigated. For this purpose, the excitation of relativistic ions with a continuous wave and a pulsed laser is analyzed, utilizing the optical Bloch equations. The laser cooling force is derived in detail and its scaling with the relativistic factor γ is discussed. The cooling processes with a continuous wave and a pulsed laser system are investigated. Optimized cooling scenarios and times are obtained in order to determine the required properties of the laser and the ion beam for the planed experiments. The impact of beam intensity effects, like intrabeam scattering and space charge are analyzed. Predictions from simplified models are compared to particle-in-cell simulations and are found to be in good agreement. Finally two realistic example cases of Carbon ions in the ESR and relativistic Titanium ions in SIS100 are compared in order to discuss prospects for future laser cooling experiments.

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Transverse Laser Cooling of a Fast Stored Ion Beam through Dispersive Coupling

Cited by 53 publications

References 18 publications

Low-Current, Vertical Blowup in a Stored Laser-Cooled Ion Beam

Low-Current, Vertical Blowup in a Stored Laser-Cooled Ion Beam

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Cooling rates and intensity limitations for laser-cooled ions at relativistic energies

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