LINAC2014 - List of Authors (Voss, K.-O.)

Paper	Title	Page
TUPP057	In Situ Measurement of Mechanical Vibrations of a 4-Rod RFQ at GSI	553
	P. Gerhard, L. Groening, K.-O. Voss GSI, Darmstadt, Germany
	A new 4-rod CW Radio Frequency Quadrupole was commissioned at the high charge state injector HLI at the UNILAC in 2009. It is in operation since 2010. At high rf amplitudes strong modulations of the rf reflection emerge, with a modulation frequency of approximately 500 Hz. They are attributed to mechanical oscillations of the rods, excited by the rf pulse. The high fraction of reflected rf power severely limits the pulse length and rf amplitude achievable. As these modulations could only be seen during the rf pulse by means of rf measurements, a direct observation of the mechanical vibrations was desirable. Such measurements have been conducted using a commercial laser vibrometer, allowing for the investigation of the mechanical behavior of the RFQ independent of the presence of rf power. After a short introduction of the method, the results will be presented and compared with rf measurements and simulations. : P. Gerhard et al., “Experience with a 4–Rod CW RFQ”, LINAC’12, Sept. 2012, Tel Aviv, THPB035

Paper

Title

Page

In Situ Measurement of Mechanical Vibrations of a 4-Rod RFQ at GSI

553

P. Gerhard, L. Groening, K.-O. Voss
GSI, Darmstadt, Germany

A new 4-rod CW Radio Frequency Quadrupole was commissioned at the high charge state injector HLI at the UNILAC in 2009. It is in operation since 2010*. At high rf amplitudes strong modulations of the rf reflection emerge, with a modulation frequency of approximately 500 Hz. They are attributed to mechanical oscillations of the rods, excited by the rf pulse. The high fraction of reflected rf power severely limits the pulse length and rf amplitude achievable. As these modulations could only be seen during the rf pulse by means of rf measurements, a direct observation of the mechanical vibrations was desirable. Such measurements have been conducted using a commercial laser vibrometer, allowing for the investigation of the mechanical behavior of the RFQ independent of the presence of rf power. After a short introduction of the method, the results will be presented and compared with rf measurements and simulations.
*: P. Gerhard et al., “Experience with a 4–Rod CW RFQ”, LINAC’12, Sept. 2012, Tel Aviv, THPB035