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Gonin, I

Publications and source records attributed to Gonin, I.

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Resonance Excitation of Longitudinal High Order Modes in Project X Linac

Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Resonance effects of longitudinal HOMS in Project X linac

Results of analysis of losses due to excitation of longitudinal high order modes (HOMs) in the accelerating RF system of the CW proton linac of the Project X facility are presented. The necessity of HOM dampers in the superconducting (SC) cavities of the linac is discussed. Project X is a multi-MW proton source which is under development at Fermilab. The facility is based on a 3 GeV CW linac. The main fraction of H{sup -} beam from the linac is split into three parts for Mu2e experiment, kaon experiments, and another which is not yet decided. The layout of the linac is shown in Figure 1. It includes three sections based on 325 MHz single-spoke cavities, and a low-energy and a high-energy sections of 650 MHz elliptical cavities with geometrical beta of 0.61 and 0.9, respectively. The linac provides a beam with an average current of 1 mA and time structure (shown in Figure 2) devised to satisfy specific requirements of the experiments. Each bunch contains 9 {center_dot} 10{sup 7} H{sup -} ions. The bunch sequence frequency for the Mu2e experiment is 162.5 MHz with a total pulse duration of 100 ns and pulse repetition rate of 1 MHz. The bunch sequence frequency for Kaon and other experiments is 27.08 MHz. Figure 3 shows the idealized beam current spectrum, which contains harmonics of multiplies of 27.08 MHz and harmonics of multiplies of 1 MHz. The 5-cell 650 MHz cavities for Project X are currently under development. A critical design decision is to define the necessity of HOM dampers for these types of cavities.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Microphonics control for Project X

The proposed multi-MW Project X facility at Fermilab will employ cavities with bandwidths as narrow as 20 Hz. This combination of high RF power with narrow bandwidths combined requires careful attention to detuning control if these cavities are to be operated successfully. Detuning control for Projects X will require a coordinated effort between the groups responsible for various machine subsystems. Considerable progress in this area has been made over the past year. Detuning levels in the Project X cavities, specifically the Low and High {beta} 650 MHz elliptical types, can have a significant impact on the overall cost of the project. The narrow bandwidths, and the high RF Power requirements, and the large number of these cavities mean that careful attention to detuning control will be required if these cavities are to operate successfully. Limiting cavity detuning in Project X will require a coordinated effort between the groups responsible for various subsystems of the planned machine. Considerable progress towards this goal has been made by each of these groups over the past year.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Status of the mechanical design of the 650 MHz cavities for Project X

In the high-energy section of the Project X Linac, acceleration of H{sup -} ions takes place in superconducting cavities operating at 650 MHz. Two families of five-cell elliptical cavities are planned: beta = 0.61 and beta = 0.9. A specific feature of the Project X Linac is low beam loading, and thus, low bandwidth and higher sensitivity to microphonics. Efforts to optimize the mechanical design of the cavities to improve their mechanical stability in response to the helium bath pressure fluctuations will be presented. These efforts take into account constraints such as cost and ease of fabrication. Also discussed will be the overall design status of the cavities and their helium jackets. The proposed design of the 3 GeV Project X superconducting (SC) Linac employs 650 MHz five-cell elliptical cavities to accelerate 1.0 mA of average H-beam current in the 160-3000 MeV energy range. The 650 MHz region of the Linac is divided into two sections with two different geometric phase velocity factors: beta = 0.61 to cover the 160-520 MeV range and beta = 0.9 to cover the 520-3000 MeV range. Approximately 40 beta = 0.61 and 150 beta = 0.9 cavities are currently planned for the project. An R&D program is in progress at FNAL, in collaboration with TJNAF and India, to develop the 650 MHz cavities for the proposed Linac design. This R&D program includes the design and fabrication of several beta = 0.61 and beta = 0.9 single-cell prototypes for evaluation prior to production of the five-cell cavities. FNAL has contracted AES to fabricate the beta = 0.9 prototypes, while TJNAF is building beta = 0.61 prototypes of their own design. In the remainder of this paper we will restrict our discussion to the five-cell beta = 0.9 cavities.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Progress in cavity and cryomodule design for the Project X linac

The continuous wave 3 GeV Project X Linac requires the development of two families of cavities and cryomodules at 325 and 650 MHz. The baseline design calls for three types of superconducting single-spoke resonators at 325 MHz having betas of 0.11, 0.22, and 0.42 and two types of superconducting five-cell elliptical cavities having betas of 0.61 and 0.9. These cavities shall accelerate a 1 mA H- beam initially and must support eventual operation at 4 mA. The electromagnetic and mechanical designs of the cavities are in progress and acquisition of prototypes is planned. The heat load to the cryogenic system is up to 25 W per cavity in the 650 MHz section, thus segmentation of the cryogenic system is a major issue in the cryomodule design. Designs for the two families of cryomodules are underway.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Concept em design of the 650 MHz cavities for the Project X

Concept of the 650 MHz cavities for the Project X is presented. Choice of the basic parameters, i.e., number of cells, geometrical {beta}, apertures, coupling coefficients, etc., is discussed. The cavity optimization criteria are formulated. Results of the RF design are presented for the cavities of both the low-energy and high-energy sections.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

High-Gradient Tests of the Single-Cell SC Cavity with a Feedback Waveguide

Use of a superconducting (SC) traveling-wave accelerating (STWA) structure with a small phase advance per cell, rather than a standing-wave structure, may provide a significant increase in the accelerating gradient in the ILC linac [1]. For the same surface electric and magnetic fields, the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing-wave cavities. In addition, the STWA allows longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed and manufactured to demonstrate the possibility of proper processing to achieve a high accelerating gradient. The first results of high-gradient tests of a prototype 1.3 GHz single-cell cavity with feedback waveguide will be presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

CW RF system of the Project-X accelerator front end

Front end of a CW linac of the Project X contains an H{sup -} source, an RFQ, a medium energy transport line with the beam chopper, and a SC low-beta linac that accelerates H{sup -} from 2.5 MeV to 160 MeV. SC Single Spoke Resonators (SSR) will be used in the linac, because Fermilab already successfully developed and tested a SSR for beta = 0.21. Two manufactured cavities achieve 2.5 times more than design accelerating gradients. One of these cavities completely dressed, e.g. welded to helium vessel with integrated slow and fast tuners, and tested in CW regime. Successful tests of beta = 0.21 SSR give us a confidence to use this type of cavity for low beta (0.117) and for high-beta (0.4) as well. Both types of these cavities are under development. In present report the basic constrains, parameters, electromagnetic and mechanical design for all the three SSR cavities, and first test results of beta = 0.21 SSR are presented.

43 PARTICLE ACCELERATORS↗