| Paper | Title | Page |
|---|---|---|
| CT04 | The Beam Inhibit System for TTF II | 62 |
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| The new generation of light sources based on SASE Free-Electron-Lasers driven by LINACs operate with electron beams with high beam currents and duty cycles. This is especially true for the superconducting machines like TTF II and the X-RAY FEL, under construction or planning at DESY. Elaborate fast protections systems are required not only to protect the machine from electron beams hitting and destroying the vacuum chamber, but also to prevent the machine from running at high loss levels, dangerous for components like the FEL undulator. This paper will give an overview over the different protection systems currently under construction for TTF II. The very fast systems, based on transmission measurements and distributed loss detection monitors, will be described in detail. This description will include the fast electronics to collect and to transmit the different interlock signals. | ||
| PM15 | First Experimental Results And Improvements On Profile Measurements With The Vibrating Wire Scanner | 128 |
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| The paper presents the first experimental results of transverse profile scans using a wire scanner based on a vibrating wire (vibrating wire scanner - VWS). The measurements were performed at the injector electron beam (6 nA) of the Yerevan synchrotron. The beam profile information is obtained by measuring the wire natural oscillations that depend on the wire temperature. This first experiments on weak electron beam proved this new method as a very sensitive tool, even suitable for tail measurements. Additional, improvements were tested to overcome some problems connected with signal conditioning and signal transfer in the presence of electromagnetic noise. As a result the noises were neatly separated and reduced. A mathematical method for rejection of distorted data was developed. Experiments with the scanner at the PETRA accelerator at DESY are planned for measurements of beam tails. | ||
| PT26 | Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla | 234 |
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| A newly high performance SQUID based measurement system for detecting dark currents, generated by superconducting cavities for TESLA is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the nA range with a small signal bandwidth of 70 kHz. To reach the maximum possible energy in the TESLA project is a strong motivation to push the gradients of the superconducting cavities closer to the physical limit of 50 MV/m. The field emission of electrons (the so called dark current) of the superconducting cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. This contribution describes a Cryogenic Current Comparator (CCC) as an excellent and useful tool for this purpose. The most important component of the CCC is a high performance DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current. For this reason the SQUID input coil is connected across a special designed pick-up coil for the electron beam. Both the SQUID input coil and the pick-up coil form a closed superconducting loop so that the CCC is able to detect dc currents down to 2 pA/√Hz. Design issues and the application for the CHECHIA cavity test stand at DESY as well as preliminary experimental results are discussed. | ||
| DW01 | Machine Protection And Interlock Systems
Session 1: Wednesday (11:15--13:00 Hrs) |
259 |
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| The purpose of a MPS is to protect the equipment against abnormal beam behaviour. High intense and high brilliant particle, photon and X-ray beams are capable of causing significant damage to components in a fraction of a second, i.e. too fast for any human reaction. The aim of this session is to discuss existing and planned MPS with both their specific and their general requirements. Among points to be reviewed: the choice of sensors and components, the logic, the strategy, etc. in view of the need for the MPS to be fail-proof. Some typical questions that will be raised: What are the criteria for determining that an alarm situation has been reached and what is the subsequent action of the system? Very often the MPS may allow different beam modes, depending on beam permit inputs. Which kind of beam modes exist and what are the input signals? How are these systems integrated with the accelerator controls and what is the impact on their operation? This session will include a few very brief presentations of existing and planned MPS' from different machines to illustrate the above questions and to stimulate the subsequent discussion. |