TY - CONF AU - Kuriki, M. AU - Nagoshi, H. AU - Negishi, K. AU - Okugi, T. AU - Omori, T. AU - Satoh, M. AU - Seimiya, Y. AU - Sumitomo, Y. AU - Takahashi, T. AU - Urakawa, J. AU - Yokoya, K. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Electron Driven Positron Source for International Linear Collider J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - To linear colliders, huge amount of positron has to be provided comparing to ring colliders, because the beam is dumped after the collision. Electron Driven ILC Positron source has been designed as a technical backup of the undulator position source including the beam loading effect, etc. The design of the detail will be presented. To linear colliders, huge amount of positron has to be provided comparing to ring colliders, because the beam is dumped after the collision. Electron Driven ILC Positron source has been designed as a technical backup of the undulator position source including the beam loading effect, etc. The design of the detail will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 439 EP - 441 KW - positron KW - beam-loading KW - linac KW - simulation KW - cavity DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPMP008 UR - http://jacow.org/ipac2019/papers/mopmp008.pdf ER - TY - CONF AU - Kuriki, M. AU - Hayano, H. AU - Jin, X.J. AU - Kashiwagi, S. AU - Konomi, T. AU - Piot, P. AU - Power, J.G. AU - Sakaue, K. AU - Seimiya, Y. AU - Tamura, R. AU - Washio, M. AU - Yamamoto, N. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Effect of Initial Parameters on the Super Flat Beam Generation with the Phase-Space Rotation for Linear Colliders J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Linear collider is a concept to realize e⁺e⁻ collision beyond the limitation of the ring colliders by the synchrotron radiation. To obtain an enough luminosity, eg. 1.0·10⁺³⁴ cm⁻²sec⁻¹, the beam is focused down to nano-meter size with a high aspect ratio. This super flat beam is useful to improve the luminosity and to compensate the beam-beam effect, eg. Beamstrahlung. In a conventional design, the super-flat beam is produced by radiation damping in a storage ring. We propose to produce this super-flat beam with phase-space rotation techniques. We employ both Round to Flat Beam Transformation and Transverse to Longitudinal Emittance eXchange, the super flat beam can be generated by controlling the space-charge effect which spoiled the performance. We present the RFBT performance with respect to the initial conditions, i.e. beam size, initial emittance, solenoid field (strength and profile), etc. PB - JACoW Publishing CP - Geneva, Switzerland SP - 442 EP - 444 KW - emittance KW - simulation KW - gun KW - collider KW - solenoid DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPMP009 UR - http://jacow.org/ipac2019/papers/mopmp009.pdf ER - TY - CONF AU - Kuriki, M. AU - Masaki, K. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF₃ adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1986 EP - 1989 KW - cathode KW - electron KW - photon KW - vacuum KW - gun DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS026 UR - http://jacow.org/ipac2019/papers/tupts026.pdf ER - TY - CONF AU - Ito, K. AU - Higaki, H. AU - Kurauchi, T. AU - Okamoto, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Experimental Observation of Low-Order Collective Oscillation Modes in a Strong-Focusing Lattice J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In a conventional linear Paul trap (LPT), four electrode rods are placed symmetrically around the trap axis to generate a radio-frequency quadrupole field for transverse ion confinement. The periodic nature of the external focusing potential can give rise to serious ion losses under a specific condition. The loss mechanism is essentially the same as the coherent betatron resonance well-known in intense beam dynamics[*,**]. In fact, the collective motion of an ion plasma in the LPT is shown equivalent to that of a charged-particle beam traveling through an alternating-gradient focusing lattice. In the present study, we perform the direct measurement of low-order coherent oscillation modes in the LPT by detecting image currents induced on the electrodes’ surfaces. The four-rod structure of the LPT allows us to pick up feeble signals of the dipole and quadrupole oscillations of a plasma bunch. These signals are Fourier analyzed to evaluate the coherent oscillation tune at different initial ion densities. The time evolution of the coherent motion is also discussed in this paper. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3130 EP - 3133 KW - quadrupole KW - plasma KW - resonance KW - dipole KW - experiment DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS018 UR - http://jacow.org/ipac2019/papers/wepts018.pdf ER - TY - CONF AU - Ito, K. AU - Higaki, H. AU - Masuda, T. AU - Okamoto, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Accumulating Laser-Coolable Ions in a Linear Paul Trap for Ultrahigh-Density Beam Dynamics Experiment J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - An ion plasma confined in a linear Paul trap (LPT) exhibits the dynamic behavior physically equivalent to that of a charged-particle beam in an alternating-gradient transport channel. The Simulator of Particle Orbit Dynamics (S-POD) is a compact apparatus designed on the basis of this fact for diverse beam-physics experiments. We have so far employed Ar+ ions that can readily be produced from neutral Ar gas atoms through the electron bombardment process. A space-charge-induced tune shift of up to about 20% of the bare tune can be achieved in Ar+ plasmas [*]. We are now preparing for future S-POD experiment to explore even higher beam-density regions. For this purpose, a large number of Ca+ ions need to be stored in the LPT. Since S-POD is equipped with a powerful laser cooler for Ca+, the use of this ion species vastly expands the density range we can survey. The production of an intense bunch of Ca+ ions is, however, not so easy because of some technical reasons. By optimizing the operating condition of a multi-sectioned LPT, we succeeded in increasing the number of accumulated Ca+ ions to the level comparable to Ar+ ion plasmas. This paper reports on updated results of the experiment. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3134 EP - 3137 KW - experiment KW - plasma KW - laser KW - accumulation KW - quadrupole DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS019 UR - http://jacow.org/ipac2019/papers/wepts019.pdf ER - TY - CONF AU - Okamoto, H. AU - Kojima, K. AU - Tokashiki, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Stability Tune Diagram of a High-Intensity Hadron Ring J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - To date, the optimum operating point of a high-intensity hadron ring has been determined on the basis of the conventional incoherent picture. It is generally chosen on the tune diagram such that the so-called "incoherent tune spread" of a stored beam does not overlap with low-order "single-particle resonance" lines. We here propose a new approach to construct the stability tune diagram on the basis of the self-consistent coherent picture. The betatron resonance condition recently conjectured from one-dimensional Vlasov predictions is employed for this purpose, which predicts the existence of twice as many resonance stop bands as expected from the well-known incoherent resonance condition at high beam density *,**. The proposed general rules for the stability-chart construction are very simple and free from any model-dependent unobservables like space-charge-depressed incoherent tunes. As an example, we apply the present rules to the lattice of the rapid cycling synchrotron at J-PARC and explain why the operating bare tunes of this machine have been chosen slightly below 6.5 in both transverse directions. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3141 EP - 3144 KW - resonance KW - emittance KW - space-charge KW - lattice KW - betatron DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS022 UR - http://jacow.org/ipac2019/papers/wepts022.pdf ER - TY - CONF AU - Okamoto, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Hamiltonian Formalism of Intense Beams in Drift-Tube Linear Accelerators J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Starting from the principle of least action, we construct a general Hamiltonian formalism for beam dynamics in drift-tube linear accelerators (DTLs). The Alvarez-type structure is considered here as an example, but the present theory can readily be extended to other types of conventional linacs. The three-dimensional Hamiltonian derived includes the third-order chromatic term as well as the effects from acceleration and space charge. A clear dynamical analogy between the DTL system and compact Paul ion-trap system is pointed out, which indicates that we can conduct a fundamental design study of high-intensity hadron linacs experimentally in a local tabletop environment instead of relying on large-scale machines. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3145 EP - 3147 KW - DTL KW - quadrupole KW - space-charge KW - acceleration KW - focusing DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS023 UR - http://jacow.org/ipac2019/papers/wepts023.pdf ER - TY - CONF AU - Xu, T. AU - Conde, M.E. AU - Ha, G. AU - Kuriki, M. AU - Piot, P. AU - Power, J.G. AU - Wisniewski, E.E. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Generation High-Charge of Flat Beams at the Argonne Wakefield Accelerator J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Beams with large transverse emittance ratios (flat beams)have received renewed interest for their possible applications in future linear colliders and advanced accelerators. A flat beam can be produced by generating a magnetized beam and then repartitioning its emittance using three skew quadrupoles. In this paper, we report on the experimental generation of∼1nC flat beams at the Argonne WakefieldAccelerator (AWA). The emittance ratio of the flat beam is demonstrated to be continuously variable by adjusting the magnetic field on the cathode. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3337 EP - 3340 KW - emittance KW - solenoid KW - electron KW - quadrupole KW - experiment DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS094 UR - http://jacow.org/ipac2019/papers/wepts094.pdf ER -