Experimental verification of resonance instability bands in quadrupole doublet focusing channels

Fukushima, Kei; Ito, K.; Okamoto, Hiromi; Yamaguchi, S.; Moriya, K.; Higaki, Hidehiko; Okano, T.; Lund, Steven M.

doi:10.1016/j.nima.2013.05.101

Cited by 17 publications

(33 citation statements)

References 17 publications

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“…So far, we have mostly implemented single-harmonic sinusoidal (or multi-harmonic sinusoidal) excitation rather than the more difficult-to-synthesize step-function excitations The simplest single-harmonic sinusoidal waveform suffices for exploring the fundamental features of quadrupole doublet focusing channels. We have demonstrated experimentally and numerically that the distribution of space-charge-induced resonance stop bands in this sinusoidal focusing case is almost identical to that in the most popular doublet (FODO) channels over a broad range of parameters [24]. The stop-band distributions measured in S-POD II and III are shown in Fig.…”

Section: Coherent Stop-band Verificationmentioning

confidence: 68%

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Experimental simulation of beam propagation over long path lengths using radio-frequency and magnetic traps

Okamoto

Endo

Fukushima

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Coherent Stop-band Verificationmentioning

confidence: 68%

“…Details of the simulations, including numerical parameters and choices in initial distribution functions, can be found in Refs. [12,24,29].…”

Section: Lattice Symmetry and Stop Bandsmentioning

confidence: 99%

Experimental simulation of beam propagation over long path lengths using radio-frequency and magnetic traps

Okamoto

Endo

Fukushima

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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“…We have emphasized the importance of the parametric resonance condition (7) since its discovery [27,31,[35][36][37][38][39][40][41], presenting not only systematic numerical simulation data but also various experimental observations from the novel tabletop apparatus "S-POD" (Simulator of Particle Orbit Dynamics) at Hiroshima University [42][43][44]. S-POD reproduces, within a very compact ion trap [45], the collective behavior of an intense beam propagating through a wide range of AG lattice configurations; see Appendix B for some information about S-POD.…”

Section: Empirical 2d Coherent Resonance Conditionmentioning

confidence: 99%

Empirical condition of betatron resonances with space charge

Kojima

Okamoto

Tokashiki

2019

Phys. Rev. Accel. Beams

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This paper addresses the generalization of the single-particle betatron resonance condition derived by Courant and Snyder more than a half century ago. A two-dimensional resonance condition including the effect of space-charge interaction was recently conjectured from one-dimensional Vlasov predictions made by Sacherer, Okamoto, and Yokoya [K. Ito et al., Phys. Rev. Accel. Beams 20, 064201 (2017)]. The condition is remarkably simple which only contains a few measurable quantities and indicates the possibility that twice as many resonance stop bands as expected from the conventional incoherent picture may exist at high beam density. Self-consistent multiparticle simulations are performed systematically to locate low-order stop bands in the tune diagram. The proposed betatron resonance formula is shown to explain the basic feature of numerical observations, which suggests that no serious incoherent resonance is activated inside the phase-space core of a dense beam matched to the external linear focusing potential. It is confirmed that the coherent tune-shift factor of any collective mode is less than unity and practically considered as a constant over the whole tune space in a typical high-intensity storage ring. The procedure for finding the optimum operating point of the ring is discussed on the basis of the coherent picture instead of the commonly used picture relying on the concept of incoherent tune spread. Despite years of theoretical efforts by many researchers, the coherent resonance concept is still not being employed for the construction of a stability tune diagram. We here provide a simple prescription to draw the diagram quickly. The present study also indicates the possibility of complete suppression of emittance exchange on particular difference resonances by choosing a proper emittance ratio.

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“…It has been studied theoretically [1][2][3][4][5][6][7][8] and experimentally [9][10][11] since the 1980s. In recent years, there was growing interest in further understanding this instability and other structural resonances [12][13][14][15][16][17][18][19][20][21][22]. Some of those studies were summarized in a recently published monograph [23].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional envelope instability in periodic focusing channels

Qiang

2018

Phys. Rev. Accel. Beams

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The space-charge driven envelope instability can be of great danger in high intensity accelerators and was studied using a two-dimensional (2D) envelope model and three-dimensional (3D) macroparticle simulations before. In this paper, we study the instability for a bunched beam using a three-dimensional envelope model in a periodic solenoid and radio-frequency (rf) focusing channel and a periodic quadrupole and rf focusing channel. This study shows that when the transverse zero current phase advance is below 90°, the beam envelope can still become unstable if the longitudinal zero current phase advance is beyond 90°. For the transverse zero current phase advance beyond 90°, the instability stopband width becomes larger with the increase of the longitudinal focusing strength and even shows different structure from the 2D case when the longitudinal zero current phase advance is beyond 90°. Breaking the symmetry of two longitudinal focusing rf cavities and the symmetry between the horizontal focusing and the vertical focusing in the transverse plane in the periodic quadrupole and rf channel makes the instability stopband broader. This suggests that a more symmetric accelerator lattice design might help reduce the range of the envelope instability in parameter space.

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Experimental verification of resonance instability bands in quadrupole doublet focusing channels

Cited by 17 publications

References 17 publications

Experimental simulation of beam propagation over long path lengths using radio-frequency and magnetic traps

Experimental simulation of beam propagation over long path lengths using radio-frequency and magnetic traps

Empirical condition of betatron resonances with space charge

Three-dimensional envelope instability in periodic focusing channels

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