IPAC2016 - List of Authors (Oegren, J.)

Paper	Title	Page
MOPMR022	Beam-based Alignment of CLIC Accelerating Structures Utilizing Their Octupole Component	280
	J. Ögren, V.G. Ziemann Uppsala University, Uppsala, Sweden
	Alignment of the accelerating structures is essential for emittance preservation in long linear accelerators such as the Compact Linear Collider (CLIC). The prototype structures for CLIC have four radial waveguides connected to each cell for damping wakefields and this four-fold symmetry is responsible for an octupole component of the radio-frequency fields, phase-shifted 90 degrees with respect to the accelerating mode. The octupole field causes a nonlinear dependence of the transverse beam deflection with respect to the position within the accelerating structure. By transversely moving the beam with two upstream steering magnets, and observing the deflection with beam position monitors or screens, the electromagnetic center of the structure can be found. We discuss the applicability of this method for aligning the beam in the accelerating structures.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR022
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MOPMR023	Surface Characterization and Field Emission Measurements of Copper Samples inside a Scanning Electron Microscope	283
	J. Ögren, V.G. Ziemann Uppsala University, Uppsala, Sweden S.H.M. Jafri, K. Leifer Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
	Vacuum breakdown in normal-conducting accelerating structures is a limiting factor for high gradient acceleration. Many aspects of the physics governing the breakdown process and its onset are yet to be fully understood. At Uppsala University we address these questions with an in-situ experimental setup mounted in an environmental scanning electron microscope. It consists of a piezo motor driven tungsten needle and a sample surface mounted on a piezo stage, allowing for nano-meter 3D-position control. One of the piezo motors controls the needle-sample gap while the two other scan across the surface. A DC-voltage up to 1 kV is applied across the gap and field emission currents from a copper surface are measured with an electrometer. Here we present the setup and some initial results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR023
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Paper

Title

Page

Beam-based Alignment of CLIC Accelerating Structures Utilizing Their Octupole Component

280

J. Ögren, V.G. Ziemann
Uppsala University, Uppsala, Sweden

Alignment of the accelerating structures is essential for emittance preservation in long linear accelerators such as the Compact Linear Collider (CLIC). The prototype structures for CLIC have four radial waveguides connected to each cell for damping wakefields and this four-fold symmetry is responsible for an octupole component of the radio-frequency fields, phase-shifted 90 degrees with respect to the accelerating mode. The octupole field causes a nonlinear dependence of the transverse beam deflection with respect to the position within the accelerating structure. By transversely moving the beam with two upstream steering magnets, and observing the deflection with beam position monitors or screens, the electromagnetic center of the structure can be found. We discuss the applicability of this method for aligning the beam in the accelerating structures.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMR023

Surface Characterization and Field Emission Measurements of Copper Samples inside a Scanning Electron Microscope

283

J. Ögren, V.G. Ziemann
Uppsala University, Uppsala, Sweden
S.H.M. Jafri, K. Leifer
Uppsala University, Department of Engineering Sciences, Uppsala, Sweden

Vacuum breakdown in normal-conducting accelerating structures is a limiting factor for high gradient acceleration. Many aspects of the physics governing the breakdown process and its onset are yet to be fully understood. At Uppsala University we address these questions with an in-situ experimental setup mounted in an environmental scanning electron microscope. It consists of a piezo motor driven tungsten needle and a sample surface mounted on a piezo stage, allowing for nano-meter 3D-position control. One of the piezo motors controls the needle-sample gap while the two other scan across the surface. A DC-voltage up to 1 kV is applied across the gap and field emission currents from a copper surface are measured with an electrometer. Here we present the setup and some initial results.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)