WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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  • Article
    Citation - WoS: 2
    Mitigation of Electron Cloud Effects in the FCC-EE Collider
    (Springer Science and Business Media Deutschland GmbH, 2022) Yaman, F.; Iadarola, G.; Kersevan, R.; Oğur, S.; Ohmi, K.; Zimmermann, F.; Zobov, M.
    Electron clouds forming inside the beam vacuum chamber due to photoemission and secondary emission may limit the accelerator performance. Specifically, the electron clouds can blow up the vertical emittance of a positron beam, through a head-tail-type single-bunch instability, if the central electron density exceeds a certain threshold value, that can be estimated analytically. Using the codes PyECLOUD and VSim, we carried out detailed simulations of the electron-cloud build up for the main arcs and the damping ring of the FCC-ee collider, in order to identify the effective photoemission rate and secondary emission yield required for achieving and maintaining the design emittance. To this end, we present the simulated electron density at the centre of the beam pipe for various bunch spacings, secondary emission yields, and photoemission parameters, in the damping ring and in the arcs of the collider positron ring. To gain further insight into the underlying dynamics, the obtained spatial and energy distributions of the cloud electrons are illustrated as a function of time. In addition, we compare results obtained for two different secondary emission models (“Furman–Pivi” and “ECLOUD”), thereby indicating the uncertainty inherent in this type of study, without any prototype vacuum chambers yet available. We also point out a few situations where the two secondary-emission models yield similar density values. Finally, based on our simulation results for two different design variants, we conclude that the new parameter baseline of the FCC-ee will facilitate electron-cloud mitigation. © 2022, The Author(s).
  • Article
    Citation - WoS: 5
    Citation - Scopus: 6
    Active Heat Transfer Enhancement by Interface-Localized Liquid Dielectrophoresis Using Interdigitated Electrodes
    (Elsevier, 2022) Yenigün, Onur; Barışık, Murat
    We introduced an active heat transfer control between graphene and water using interdigitated electrodes (IDEs). Oppositely charged co-planer electrodes embedded on a graphene surface created a non-uniform electric field. Resulted interface localized liquid dielectrophoresis (LDEP) perpendicular to surface enhanced the water/graphene coupling and decreased interfacial thermal resistance (ITR) substantially. We correlated the theoretical calculations of average electric field strength near surface with Kapitza values measured at corresponding electrode configurations. We obtained a unified linear variation of Kapitza as a function of average electric strength independent of electrode size and charge. By increasing the electric field strength, we measured up to 96% decrease of Kapitza near electrodes. Since the IDEs generated electric field was only interface localized, it required lower electrode charges than any parallel-plate capacitor systems. We showed that ITR remains effective in heat transfer behavior for systems as big as 100nm such that interface localized electric field can at least increase the heat removal 50% by eliminating the ITR from both graphene/water interfaces of a channel system. By converting hydrophobic few-layer graphene to super-hydrophilic condition with ultra-low Kapitza, current results are important for graphene-based materials considered for the solution of the thermal management problem of current and next generation micro/nano-electronics.
  • Conference Object
    A sustainable association case study: IFToMM member organization Turkey
    (Springer, 2022) Kiper, Gökhan; Söylemez, Eres
    As a member of IFToMM founded in 2011, Turkish Machine Theory Association’s (MakTeD) structure has put special emphasis on sustainability of the association and initiated several activities for improving the quality of education and research in mechanism and machine science area, hence supporting the SDG4 Quality Education of the UN. This paper presents the activities and methodologies of MakTeD. The paper starts with a brief history of mechanism and machine science in Turkey. In 10 years MakTeD organized 4 symposiums, 1 conference, 4 summer/winter schools, 8 workshops and hosted an IFToMM Executive Council meeting. Each chapter of the biyearly held National Symposium on Theory of Machines is held by a different university and especially newly established and the universities in relatively smaller cities are prioritized in order to promote those universities and to contribute to development of these universities. Especially the summer/winter schools and workshops have a widespread impact on mechanism and machine science education and research at the universities and institutions. MakTeD also contributes to the community with published books and support programs for young researchers.