LINAC2014 - List of Authors (Kurennoy, S.S.)

Paper	Title	Page
MOPP106	3D Mode Analysis of Full Tanks in Drift-Tube Linacs	300
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio. [1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

THPP097	3D Effects in RFQ Accelerators	1077
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	RFQ accelerators are usually designed and modeled with standard codes based on electrostatic approximations. Recent examples show that this approach fails to accurately predict the performance for 4-rod RFQs: 3D RF effects near the vane ends can noticeably influence the beam dynamics. The same applies to any RFQ where the quadrupole symmetry is broken, e.g., 4-vane RFQ with windows. We analyzed two 201.25-MHz 4-rod RFQs – one recently commissioned at FNAL and a new design for LANL – using 3D modeling with CST Studio. In both cases the manufacturer CAD RFQ model was imported into CST. The electromagnetic analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio (PS). For the LANL RFQ with duty factor up to 15%, a thermal-stress analysis with ANSYS was also performed. The simulation results for FNAL RFQ helped our Fermilab colleagues fix the low output beam energy. The LANL RFQ design was modified after CST simulations indicated insufficient tuning range and incorrect output energy; the modified version satisfies the design requirements.

Paper

Title

Page

3D Mode Analysis of Full Tanks in Drift-Tube Linacs

300

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio.
[1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

THPP097

3D Effects in RFQ Accelerators

1077

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

RFQ accelerators are usually designed and modeled with standard codes based on electrostatic approximations. Recent examples show that this approach fails to accurately predict the performance for 4-rod RFQs: 3D RF effects near the vane ends can noticeably influence the beam dynamics. The same applies to any RFQ where the quadrupole symmetry is broken, e.g., 4-vane RFQ with windows. We analyzed two 201.25-MHz 4-rod RFQs – one recently commissioned at FNAL and a new design for LANL – using 3D modeling with CST Studio. In both cases the manufacturer CAD RFQ model was imported into CST. The electromagnetic analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio (PS). For the LANL RFQ with duty factor up to 15%, a thermal-stress analysis with ANSYS was also performed. The simulation results for FNAL RFQ helped our Fermilab colleagues fix the low output beam energy. The LANL RFQ design was modified after CST simulations indicated insufficient tuning range and incorrect output energy; the modified version satisfies the design requirements.