Abstract
Efficient tuning of complex accelerator chains requires automated procedures, themselves reliant upon beam physical models. The Isotope Separator and ACcelerator (ISAC) facility at TRIUMF requires frequent changes of beam species (isotope), mass to charge ratio and beam energy tailored to experiment requirements, which demands rapid beam tuning. In addition, emergent effects such as long term changes of energy or energy spread require beam optimization that must be based on a complete model of the accelerator. Using an envelope code to build an end-to-end simulation of the accelerator facility for operational purposes reduces computing times by 3 or 4 orders of magnitude, when compared to particle tracking codes, so that the requisite simulations may be carried out in real time, by polling control system data. Herein described is the second order Hamiltonian for an radio frequency quadrupole (RFQ), presented within the framework of the envelope code transoptr. To benchmark the transoptr model, envelope simulations of the TRIUMF-ISAC RFQ have been performed and compared with the multiparticle code parmteq.
Highlights
As the complexity and the intensity requirements of modern heavy ion accelerators have increased over the past decade, the community is working towards model based tuning approaches with beam measurement based refinements
This method and its variants pose a computational burden which results in total computation times generally on the order of several dozen seconds, if not minutes, as the particle population increases to investigate effects like halo formation and beam losses. While this computational burden is not a critical issue during the design and testing phases, it does pose a problem if one wishes to implement a fast, nearly real-time simulation of an existing accelerator based upon current machine setpoints. Such a requirement has emerged at ISAC (Isotope Separator and ACcelerator), TRIUMF’s radioisotope beam (RIB) facility, whose heavy-ion postaccelerator consists of a 35.36 MHz CW radio frequency quadrupoles (RFQ), featuring external three-harmonic prebunching 5 m upstream [1], followed by a 106 MHz drift tube linac (DTL) [2]
We introduce our own ISAC-RFQ, compare and benchmark the TRANSOPTR envelope calculation with the PARMTEQ calculation, and show as a use case how the new possibility of end-to-end TRANSOPTR calculation refines the match to the RFQ
Summary
As the complexity and the intensity requirements of modern heavy ion accelerators have increased over the past decade, the community is working towards model based tuning approaches with beam measurement based refinements. This method and its variants pose a computational burden which results in total computation times generally on the order of several dozen seconds, if not minutes, as the particle population increases to investigate effects like halo formation and beam losses While this computational burden is not a critical issue during the design and testing phases, it does pose a problem if one wishes to implement a fast, nearly real-time simulation of an existing accelerator based upon current machine setpoints. Such a requirement has emerged at ISAC (Isotope Separator and ACcelerator), TRIUMF’s radioisotope beam (RIB) facility, whose heavy-ion postaccelerator consists of a 35.36 MHz CW RFQ, featuring external three-harmonic prebunching 5 m upstream [1], followed by a 106 MHz drift tube linac (DTL) [2]. We benchmark our TRANSOPTR model by comparing its results with the particle-tracking code PARMTEQ, for the case of the ISAC-RFQ [5]
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