Design and construction of the SuperKEKB vacuum system

Abstract

Development of planar x-ray source using gated carbon nanotube emitter J. Vac. Sci. Technol. B 31, 02B110 (2013) Tungstate formation in a model scandate thermionic cathode J. Vac. Sci. Technol. B 31, 011210 (2013) Influence of gun design on Coulomb interactions in a field emission gun J. Vac. Sci. Technol. B 29, 06F605 (2011) Model scandate cathodes investigated by thermionic-emission microscopyA two-ring electron-positron collider with asymmetric energies-called the SuperKEKB-has been designed by the High Energy Accelerator Research Organization (KEK) as an upgrade of the KEKB B-factory (KEKB), which completed 12 years of operation in 2010. It is anticipated that the SuperKEKB will reach a luminosity of 8 Â 10 35 cm À2 s À1 , which is approximately 40 times larger than that of the original KEKB. The upgrade of the vacuum system is a key factor that will allow the SuperKEKB to achieve unprecedented high performance. Most of the beam pipes, especially in the positron ring, are newly manufactured to manage the electron cloud effect, and to reduce beam impedance, which is essential to keep the low-emittance beam stable. Our design of the vacuum system implements recent technologies and draws on various experiences and studies during the operation of the original KEKB. The basic design is near completion, and manufacturing of beam pipes and the major vacuum components, such as bellows chambers, gate valves and supports, are in progress. The installation of these components will start in 2013 with the aim of commissioning the SuperKEKB in

Impact of the resistive wall impedance on beam dynamics in the Future Circulare+e−Collider

“…The choice of a circular pipe allows to avoid this problem. Actually the shape of the beam pipe is not totally round, but it has two winglets similar to the SuperKEKB ones [18]. They have the function of antechambers and are used for synchrotron radiation absorbers installation and pumping purposes [19].…”

Mitigating the electron cloud effect in the SuperKEKB positron ring

“…Countermeasures used to minimize the ECE in the SuperKEKB LER. The circles indicate the countermeasures applied for each main section in the ring [22,24]. Abbreviations: rf cavity section: beam pipes around rf cavities; IR: interaction region; n e (circular): electron density expected for circular beam pipe (copper); n e (expected): electron density expected after applying countermeasures; Antechamber: antechamber scheme; Solenoid: solenoid winding, manifested as a magnetic field in the beam direction (B z ); Groove: beam pipe with grooves; Electrode: beam pipe with clearing electrodes.…”

“…The electron density (n e [m −3 ]) expected in the case of circular beam pipes (copper) and those with the above countermeasures are presented in the table. For the antechamber scheme, coating, solenoid (i.e., B z ), grooved surface, and clearing electrode, the effectiveness in terms of reducing n e is assumed to be 1=5, 3=5, 1=50, 1=2, and 1=100, respectively, on the basis of previous experimental results [22,24]. Note here that these effectiveness factors are assumed to be independent of each other.…”

“…Simulations suggested that the threshold electron density (n e th [m −3 ]) at which the blowup of the beam size occurs is estimated to be ∼3 × 10 11 m −3 [17,21]. Hence, highly effective countermeasures against the ECE were required for the SuperKEKB LER [17,[21][22][23][24]. Various ECE countermeasures were prepared on the basis of studies in numerous laboratories, such as CERN [10,11,[25][26][27][28][29][30][31], Cornell University [15,[32][33][34], SLAC [12,[35][36][37], INFN [38,39], BNL [40,41], BINP [42,43], and of course, KEK [13,14,19,33,[44][45][46][47][48][49][50].…”

Study of collective effects in the FCC-ee collider

“…The beam pipe radius of 35 mm has been chosen as a compromise between the beam impedance and the power required for magnet power supplies. Actually the shape of the pipe is not totally round but additional antechambers (winglets) are foreseen for pumping purposes and installation of SR absorbers, similarly to SuperKEKB design [16]. The twin dipole and quadrupole magnets of FCC-ee are being designed incorporating this vacuum chamber cross-section [17].…”