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1. Precision feedback control of a normal conducting standing wave resonator cavity

Author

S. Pfeiffer, Ł. Butkowski, O. Hensler, M. Hoffmann, C. Schmidt, H. Schlarb, and S. Schreiber

Subjects
Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

In this paper, the system identification and feedback controller design for a normal conducting standing wave radio frequency cavity operated in pulsed mode of a free electron laser is presented. The system identification, essential to achieve high performance control, is based on a grey box model, with a priori knowledge about the physical behavior. The feedback regulation concept is separated into two basic controller parts. A radio frequency controller design, based on the identified radio frequency model, is followed by a system identification and regulation of the pulse width to overcome the limitation of the underlying temperature regulation. It will be shown by measurements at the free electron laser FLASH at DESY, Germany, that the combination of both cascaded control schemes lead to high radio frequency field performance.

Published
2018
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2. A MHz-Repetition-Rate Hard X-Ray Free-Electron Laser Driven by a Superconducting Linear Accelerator

Author

W. Decking, S. Abeghyan, P. Abramian, A. Abramsky, A. Aguirre, C. Albrecht, P. Alou, M. Altarelli, P. Altmann, K. Amyan, V. Anashin, E. Apostolov, K. Appel, D. Auguste, V. Ayvazyan, S. Baark, F. Babies, N. Baboi, P. Bak, V. Balandin, R. Baldinger, B. Baranasic, S. Barbanotti, O. Belikov, V. Belokurov, L. Belova, V. Belyakov, S. Berry, M. Bertucci, B. Beutner, A. Block, M. Blöcher, T. Böckmann, C. Bohm, M. Böhnert, V. Bondar, E. Bondarchuk, M. Bonezzi, P. Borowiec, C. Bösch, U. Bösenberg, A. Bosotti, R. Böspflug, M. Bousonville, E. Boyd, Y. Bozhko, A. Brand, J. Branlard, S. Briechle, F. Brinker, S. Brinker, R. Brinkmann, S. Brockhauser, O. Brovko, H. Brück, A. Brüdgam, L. Butkowski, T. Büttner, J. Calero, E. Castro-Carballo, G. Cattalanotto, J. Charrier, J. Chen, A. Cherepenko, V. Cheskidov, M. Chiodini, A. Chong, S. Choroba, M. Chorowski, D. Churanov, W. Cichalewski, M. Clausen, W. Clement, C. Cloué, J. A. Cobos, N. Coppola, S. Cunis, K. Czuba, M. Czwalinna, B. D’Almagne, J. Dammann, H. Danared, A. de Zubiaurre Wagner, A. Delfs, T. Delfs, F. Dietrich, T. Dietrich, M. Dohlus, M. Dommach, A. Donat, X. Dong, N. Doynikov, M. Dressel, M. Duda, P. Duda, H. Eckoldt, W. Ehsan, J. Eidam, F. Eints, C. Engling, U. Englisch, A. Ermakov, K. Escherich, J. Eschke, E. Saldin, M. Faesing, A. Fallou, M. Felber, M. Fenner, B. Fernandes, J. M. Fernández, S. Feuker, K. Filippakopoulos, K. Floettmann, V. Fogel, M. Fontaine, A. Francés, I. Freijo Martin, W. Freund, T. Freyermuth, M. Friedland, L. Fröhlich, M. Fusetti, J. Fydrych, A. Gallas, O. García, L. Garcia-Tabares, G. Geloni, N. Gerasimova, C. Gerth, P. Geßler, V. Gharibyan, M. Gloor, J. Głowinkowski, A. Goessel, Z. Gołębiewski, N. Golubeva, W. Grabowski, W. Graeff, A. Grebentsov, M. Grecki, T. Grevsmuehl, M. Gross, U. Grosse-Wortmann, J. Grünert, S. Grunewald, P. Grzegory, G. Feng, H. Guler, G. Gusev, J. L. Gutierrez, L. Hagge, M. Hamberg, R. Hanneken, E. Harms, I. Hartl, A. Hauberg, S. Hauf, J. Hauschildt, J. Hauser, J. Havlicek, A. Hedqvist, N. Heidbrook, F. Hellberg, D. Henning, O. Hensler, T. Hermann, A. Hidvégi, M. Hierholzer, H. Hintz, F. Hoffmann, Markus Hoffmann, Matthias Hoffmann, Y. Holler, M. Hüning, A. Ignatenko, M. Ilchen, A. Iluk, J. Iversen, M. Izquierdo, L. Jachmann, N. Jardon, U. Jastrow, K. Jensch, J. Jensen, M. Jeżabek, M. Jidda, H. Jin, N. Johansson, R. Jonas, W. Kaabi, D. Kaefer, R. Kammering, H. Kapitza, S. Karabekyan, S. Karstensen, K. Kasprzak, V. Katalev, D. Keese, B. Keil, M. Kholopov, M. Killenberger, B. Kitaev, Y. Klimchenko, R. Klos, L. Knebel, A. Koch, M. Koepke, S. Köhler, W. Köhler, N. Kohlstrunk, Z. Konopkova, A. Konstantinov, W. Kook, W. Koprek, M. Körfer, O. Korth, A. Kosarev, K. Kosiński, D. Kostin, Y. Kot, A. Kotarba, T. Kozak, V. Kozak, R. Kramert, M. Krasilnikov, A. Krasnov, B. Krause, L. Kravchuk, O. Krebs, R. Kretschmer, J. Kreutzkamp, O. Kröplin, K. Krzysik, G. Kube, H. Kuehn, N. Kujala, V. Kulikov, V. Kuzminych, D. La Civita, M. Lacroix, T. Lamb, A. Lancetov, M. Larsson, D. Le Pinvidic, S. Lederer, T. Lensch, D. Lenz, A. Leuschner, F. Levenhagen, Y. Li, J. Liebing, L. Lilje, T. Limberg, D. Lipka, B. List, J. Liu, S. Liu, B. Lorbeer, J. Lorkiewicz, H. H. Lu, F. Ludwig, K. Machau, W. Maciocha, C. Madec, C. Magueur, C. Maiano, I. Maksimova, K. Malcher, T. Maltezopoulos, E. Mamoshkina, B. Manschwetus, F. Marcellini, G. Marinkovic, T. Martinez, H. Martirosyan, W. Maschmann, M. Maslov, A. Matheisen, U. Mavric, J. Meißner, K. Meissner, M. Messerschmidt, N. Meyners, G. Michalski, P. Michelato, N. Mildner, M. Moe, F. Moglia, C. Mohr, S. Mohr, W. Möller, M. Mommerz, L. Monaco, C. Montiel, M. Moretti, I. Morozov, P. Morozov, D. Mross, J. Mueller, C. Müller, J. Müller, K. Müller, J. Munilla, A. Münnich, V. Muratov, O. Napoly, B. Näser, N. Nefedov, Reinhard Neumann, Rudolf Neumann, N. Ngada, D. Noelle, F. Obier, I. Okunev, J. A. Oliver, M. Omet, A. Oppelt, A. Ottmar, M. Oublaid, C. Pagani, R. Paparella, V. Paramonov, C. Peitzmann, J. Penning, A. Perus, F. Peters, B. Petersen, A. Petrov, I. Petrov, S. Pfeiffer, J. Pflüger, S. Philipp, Y. Pienaud, P. Pierini, S. Pivovarov, M. Planas, E. Pławski, M. Pohl, J. Polinski, V. Popov, S. Prat, J. Prenting, G. Priebe, H. Pryschelski, K. Przygoda, E. Pyata, B. Racky, A. Rathjen, W. Ratuschni, S. Regnaud-Campderros, K. Rehlich, D. Reschke, C. Robson, J. Roever, M. Roggli, J. Rothenburg, E. Rusiński, R. Rybaniec, H. Sahling, M. Salmani, L. Samoylova, D. Sanzone, F. Saretzki, O. Sawlanski, J. Schaffran, H. Schlarb, M. Schlösser, V. Schlott, C. Schmidt, F. Schmidt-Foehre, M. Schmitz, M. Schmökel, T. Schnautz, E. Schneidmiller, M. Scholz, B. Schöneburg, J. Schultze, C. Schulz, A. Schwarz, J. Sekutowicz, D. Sellmann, E. Semenov, S. Serkez, D. Sertore, N. Shehzad, P. Shemarykin, L. Shi, M. Sienkiewicz, D. Sikora, M. Sikorski, A. Silenzi, C. Simon, W. Singer, X. Singer, H. Sinn, K. Sinram, N. Skvorodnev, P. Smirnow, T. Sommer, A. Sorokin, M. Stadler, M. Steckel, B. Steffen, N. Steinhau-Kühl, F. Stephan, M. Stodulski, M. Stolper, A. Sulimov, R. Susen, J. Świerblewski, C. Sydlo, E. Syresin, V. Sytchev, J. Szuba, N. Tesch, J. Thie, A. Thiebault, K. Tiedtke, D. Tischhauser, J. Tolkiehn, S. Tomin, F. Tonisch, F. Toral, I. Torbin, A. Trapp, D. Treyer, G. Trowitzsch, T. Trublet, T. Tschentscher, F. Ullrich, M. Vannoni, P. Varela, G. Varghese, G. Vashchenko, M. Vasic, C. Vazquez-Velez, A. Verguet, S. Vilcins-Czvitkovits, R. Villanueva, B. Visentin, M. Viti, E. Vogel, E. Volobuev, R. Wagner, N. Walker, T. Wamsat, H. Weddig, G. Weichert, H. Weise, R. Wenndorf, M. Werner, R. Wichmann, C. Wiebers, M. Wiencek, T. Wilksen, I. Will, L. Winkelmann, M. Winkowski, K. Wittenburg, A. Witzig, P. Wlk, T. Wohlenberg, M. Wojciechowski, F. Wolff-Fabris, G. Wrochna, K. Wrona, M. Yakopov, B. Yang, F. Yang, M. Yurkov, I. Zagorodnov, P. Zalden, A. Zavadtsev, D. Zavadtsev, A. Zhirnov, A. Zhukov, V. Ziemann, A. Zolotov, N. Zolotukhina, F. Zummack, D. Zybin, Laboratoire de l'Accélérateur Linéaire (LAL), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], Astrophysics::High Energy Astrophysical Phenomena, 02 engineering and technology, 7. Clean energy, 01 natural sciences, Acceleration voltage, Linear particle accelerator, law.invention, 010309 optics, Optics, law, 0103 physical sciences, ddc:530, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Physics, business.industry, Free-electron laser, Undulator, 021001 nanoscience & nanotechnology, Laser, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Cathode ray, Physics::Accelerator Physics, 0210 nano-technology, business, Lasing threshold, Beam (structure)
Abstract

Nature photonics 14(6), 391 - 397 (2020). doi:10.1038/s41566-020-0607-z, The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created., Published by Nature Publ. Group, London [u.a.]

Published
2020
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3. Author Correction: A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Author

W. Decking, S. Abeghyan, P. Abramian, A. Abramsky, A. Aguirre, C. Albrecht, P. Alou, M. Altarelli, P. Altmann, K. Amyan, V. Anashin, E. Apostolov, K. Appel, D. Auguste, V. Ayvazyan, S. Baark, F. Babies, N. Baboi, P. Bak, V. Balandin, R. Baldinger, B. Baranasic, S. Barbanotti, O. Belikov, V. Belokurov, L. Belova, V. Belyakov, S. Berry, M. Bertucci, B. Beutner, A. Block, M. Blöcher, T. Böckmann, C. Bohm, M. Böhnert, V. Bondar, E. Bondarchuk, M. Bonezzi, P. Borowiec, C. Bösch, U. Bösenberg, A. Bosotti, R. Böspflug, M. Bousonville, E. Boyd, Y. Bozhko, A. Brand, J. Branlard, S. Briechle, F. Brinker, S. Brinker, R. Brinkmann, S. Brockhauser, O. Brovko, H. Brück, A. Brüdgam, L. Butkowski, T. Büttner, J. Calero, E. Castro-Carballo, G. Cattalanotto, J. Charrier, J. Chen, A. Cherepenko, V. Cheskidov, M. Chiodini, A. Chong, S. Choroba, M. Chorowski, D. Churanov, W. Cichalewski, M. Clausen, W. Clement, C. Cloué, J. A. Cobos, N. Coppola, S. Cunis, K. Czuba, M. Czwalinna, B. D’Almagne, J. Dammann, H. Danared, A. de Zubiaurre Wagner, A. Delfs, T. Delfs, F. Dietrich, T. Dietrich, M. Dohlus, M. Dommach, A. Donat, X. Dong, N. Doynikov, M. Dressel, M. Duda, P. Duda, H. Eckoldt, W. Ehsan, J. Eidam, F. Eints, C. Engling, U. Englisch, A. Ermakov, K. Escherich, J. Eschke, E. Saldin, M. Faesing, A. Fallou, M. Felber, M. Fenner, B. Fernandes, J. M. Fernández, S. Feuker, K. Filippakopoulos, K. Floettmann, V. Fogel, M. Fontaine, A. Francés, I. Freijo Martin, W. Freund, T. Freyermuth, M. Friedland, L. Fröhlich, M. Fusetti, J. Fydrych, A. Gallas, O. García, L. Garcia-Tabares, G. Geloni, N. Gerasimova, C. Gerth, P. Geßler, V. Gharibyan, M. Gloor, J. Głowinkowski, A. Goessel, Z. Gołębiewski, N. Golubeva, W. Grabowski, W. Graeff, A. Grebentsov, M. Grecki, T. Grevsmuehl, M. Gross, U. Grosse-Wortmann, J. Grünert, S. Grunewald, P. Grzegory, G. Feng, H. Guler, G. Gusev, J. L. Gutierrez, L. Hagge, M. Hamberg, R. Hanneken, E. Harms, I. Hartl, A. Hauberg, S. Hauf, J. Hauschildt, J. Hauser, J. Havlicek, A. Hedqvist, N. Heidbrook, F. Hellberg, D. Henning, O. Hensler, T. Hermann, A. Hidvégi, M. Hierholzer, H. Hintz, F. Hoffmann, Markus Hoffmann, Matthias Hoffmann, Y. Holler, M. Hüning, A. Ignatenko, M. Ilchen, A. Iluk, J. Iversen, M. Izquierdo, L. Jachmann, N. Jardon, U. Jastrow, K. Jensch, J. Jensen, M. Jeżabek, M. Jidda, H. Jin, N. Johansson, R. Jonas, W. Kaabi, D. Kaefer, R. Kammering, H. Kapitza, S. Karabekyan, S. Karstensen, K. Kasprzak, V. Katalev, D. Keese, B. Keil, M. Kholopov, M. Killenberger, B. Kitaev, Y. Klimchenko, R. Klos, L. Knebel, A. Koch, M. Koepke, S. Köhler, W. Köhler, N. Kohlstrunk, Z. Konopkova, A. Konstantinov, W. Kook, W. Koprek, M. Körfer, O. Korth, A. Kosarev, K. Kosiński, D. Kostin, Y. Kot, A. Kotarba, T. Kozak, V. Kozak, R. Kramert, M. Krasilnikov, A. Krasnov, B. Krause, L. Kravchuk, O. Krebs, R. Kretschmer, J. Kreutzkamp, O. Kröplin, K. Krzysik, G. Kube, H. Kuehn, N. Kujala, V. Kulikov, V. Kuzminych, D. La Civita, M. Lacroix, T. Lamb, A. Lancetov, M. Larsson, D. Le Pinvidic, S. Lederer, T. Lensch, D. Lenz, A. Leuschner, F. Levenhagen, Y. Li, J. Liebing, L. Lilje, T. Limberg, D. Lipka, B. List, J. Liu, S. Liu, B. Lorbeer, J. Lorkiewicz, H. H. Lu, F. Ludwig, K. Machau, W. Maciocha, C. Madec, C. Magueur, C. Maiano, I. Maksimova, K. Malcher, T. Maltezopoulos, E. Mamoshkina, B. Manschwetus, F. Marcellini, G. Marinkovic, T. Martinez, H. Martirosyan, W. Maschmann, M. Maslov, A. Matheisen, U. Mavric, J. Meißner, K. Meissner, M. Messerschmidt, N. Meyners, G. Michalski, P. Michelato, N. Mildner, M. Moe, F. Moglia, C. Mohr, S. Mohr, W. Möller, M. Mommerz, L. Monaco, C. Montiel, M. Moretti, I. Morozov, P. Morozov, D. Mross, J. Mueller, C. Müller, J. Müller, K. Müller, J. Munilla, A. Münnich, V. Muratov, O. Napoly, B. Näser, N. Nefedov, Reinhard Neumann, Rudolf Neumann, N. Ngada, D. Noelle, F. Obier, I. Okunev, J. A. Oliver, M. Omet, A. Oppelt, A. Ottmar, M. Oublaid, C. Pagani, R. Paparella, V. Paramonov, C. Peitzmann, J. Penning, A. Perus, F. Peters, B. Petersen, A. Petrov, I. Petrov, S. Pfeiffer, J. Pflüger, S. Philipp, Y. Pienaud, P. Pierini, S. Pivovarov, M. Planas, E. Pławski, M. Pohl, J. Polinski, V. Popov, S. Prat, J. Prenting, G. Priebe, H. Pryschelski, K. Przygoda, E. Pyata, B. Racky, A. Rathjen, W. Ratuschni, S. Regnaud-Campderros, K. Rehlich, D. Reschke, C. Robson, J. Roever, M. Roggli, J. Rothenburg, E. Rusiński, R. Rybaniec, H. Sahling, M. Salmani, L. Samoylova, D. Sanzone, F. Saretzki, O. Sawlanski, J. Schaffran, H. Schlarb, M. Schlösser, V. Schlott, C. Schmidt, F. Schmidt-Foehre, M. Schmitz, M. Schmökel, T. Schnautz, E. Schneidmiller, M. Scholz, B. Schöneburg, J. Schultze, C. Schulz, A. Schwarz, J. Sekutowicz, D. Sellmann, E. Semenov, S. Serkez, D. Sertore, N. Shehzad, P. Shemarykin, L. Shi, M. Sienkiewicz, D. Sikora, M. Sikorski, A. Silenzi, C. Simon, W. Singer, X. Singer, H. Sinn, K. Sinram, N. Skvorodnev, P. Smirnow, T. Sommer, A. Sorokin, M. Stadler, M. Steckel, B. Steffen, N. Steinhau-Kühl, F. Stephan, M. Stodulski, M. Stolper, A. Sulimov, R. Susen, J. Świerblewski, C. Sydlo, E. Syresin, V. Sytchev, J. Szuba, N. Tesch, J. Thie, A. Thiebault, K. Tiedtke, D. Tischhauser, J. Tolkiehn, S. Tomin, F. Tonisch, F. Toral, I. Torbin, A. Trapp, D. Treyer, G. Trowitzsch, T. Trublet, T. Tschentscher, F. Ullrich, M. Vannoni, P. Varela, G. Varghese, G. Vashchenko, M. Vasic, C. Vazquez-Velez, A. Verguet, S. Vilcins-Czvitkovits, R. Villanueva, B. Visentin, M. Viti, E. Vogel, E. Volobuev, R. Wagner, N. Walker, T. Wamsat, H. Weddig, G. Weichert, H. Weise, R. Wenndorf, M. Werner, R. Wichmann, C. Wiebers, M. Wiencek, T. Wilksen, I. Will, L. Winkelmann, M. Winkowski, K. Wittenburg, A. Witzig, P. Wlk, T. Wohlenberg, M. Wojciechowski, F. Wolff-Fabris, G. Wrochna, K. Wrona, M. Yakopov, B. Yang, F. Yang, M. Yurkov, I. Zagorodnov, P. Zalden, A. Zavadtsev, D. Zavadtsev, A. Zhirnov, A. Zhukov, V. Ziemann, A. Zolotov, N. Zolotukhina, F. Zummack, and D. Zybin

Subjects
Superconductivity, Optics, Materials science, Repetition (rhetorical device), business.industry, X-ray, Free-electron laser, business, Atomic and Molecular Physics, and Optics, Linear particle accelerator, Electronic, Optical and Magnetic Materials
Published
2020
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4. Precision feedback control of a normal conducting standing wave resonator cavity

Author

Matthias C. Hoffmann, C. Schmidt, Stuart L. Schreiber, Sven Pfeiffer, O. Hensler, Holger Schlarb, and Ł. Butkowski

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Acoustics, Feedback control, Surfaces and Interfaces, 01 natural sciences, 010309 optics, Standing wave, Resonator, 0103 physical sciences, lcsh:QC770-798, ddc:530, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity
Abstract

Physical review accelerators and beams 21(9), 092802 (2018). doi:10.1103/PhysRevAccelBeams.21.092802, In this paper, the system identification and feedback controller design for a normal conducting Standing wave radio frequency cavity operated in pulsed mode of a free electron laser is presented. The system identification, essential to achieve high performance control, is based on a grey box model, with a priori knowledge about the physical behavior. The feedback regulation concept is separated into two Basic controller parts. A radio frequency controller design, based on the identified radio frequency model, is followed by a system identification and regulation of the pulse width to overcome the limitation of the underlying temperature regulation. It will be shown by measurements at the free electron laser FLASH at DESY, Germany, that the combination of both cascaded control schemes lead to high radio frequency field performance., Published by American Physical Society, College Park, MD

Published
2018
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5. Wire scanner system for FLASH at DESY

Author

U. Hahn, M. Sachwitz, N.v. Bargen, S. Karstensen, O. Hensler, P. Castro, and H. Thom

Subjects
Physics, Nuclear and High Energy Physics, Scanner, business.industry, Monte Carlo method, Free-electron laser, DESY, Undulator, Flash (photography), Optics, Physics::Accelerator Physics, Laser beam quality, business, Instrumentation, Beam (structure)
Abstract

The design and implementation of a new kind of wire scanner for the Free Electron Laser at Hamburg (FLASH) is presented. In the undulator section of FLASH a set of seven wire scanner stations determine the relative position and the profile of the electron beam with a spatial resolution of a few μm. They allow the measurement of the absolute beam position related to the undulator axis with a precision better than 50 μm. Monte Carlo calculations are performed in order to get an optimal position for the scintillators, which are used to detect the secondary particles scattered by the wire. Results of beam trajectory and beam size measurements along the undulator section are presented.

Published
2008
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6. High precision SC cavity alignment measurements with higher order modes

Author

J. May, D. McCormick, N. Eddy, Josef Frisch, Nicoleta Baboi, Claire Simon, Tonee Smith, R. Paparella, Stephen Molloy, Ron Rechenmacher, O. Hensler, S. Nagaitsev, L. Piccoli, Olivier Napoly, Lyudvig Petrosyan, and Marc Ross

Subjects
Physics, 010308 nuclear & particles physics, business.industry, Applied Mathematics, Phase (waves), Electrical engineering, Particle accelerator, DESY, 01 natural sciences, Linear particle accelerator, law.invention, Dipole, Amplitude, Optics, law, 0103 physical sciences, Orbit (dynamics), Physics::Accelerator Physics, 010306 general physics, business, Instrumentation, Engineering (miscellaneous), Computer Science::Databases, Beam (structure)
Abstract

Experiments at the FLASH linac at DESY have demonstrated that the higher order modes (HOMs) induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The centers of the cavities can be determined from the beam orbit which produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used as a high resolution beam position monitor. For most superconducting accelerators, the existing HOM couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional BPM.

Published
2007
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7. Test and first application of artificial sapphire sensors

Author

Alexandr Ignatenko, Nicoleta Baboi, Michael Schmitz, Hans Henschel, Sergej Schuwalow, Wolfgang Lange, Wolfgang Lohmann, O. Hensler, and Kay Wittenburg

Subjects
Materials science, business.industry, Diamond, engineering.material, Signal, Monocrystalline silicon, Flash (photography), Absorbed dose, Sapphire, engineering, Optoelectronics, Dosimetry, business, Radiation hardening
Abstract

Samples of monocrystalline sapphire sensors of 10×10 mm2 area and 0.5 mm thickness with the initial charge collection efficiency of about 2% have been studied in electron beams. The response as a function of the absorbed dose revealed excellent radiation hardness. The signal size dropped smoothly with the absorbed dose approaching 30% of the signal of non-irradiated sensors after the dose of 12 MGy. Four sapphire sensors have been installed, together with four pCVD diamond sensors, as a beam halo monitor of the FLASH facility. A report on the commissioning and operation experience is given.

Published
2010
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8. The Vacuum System of the European X-ray Free Electron Laser XFEL

Author

K. Zapfe, O. Hensler, K. Rehlich, T Wohlenberg, A Wagner, J. Wojtkiewicz, B Nagorny, H. Remde, N Mildner, D. Hoppe, and M. Böhnert

Subjects
Physics, History, business.industry, Free-electron laser, DESY, Undulator, Linear particle accelerator, Computer Science Applications, Education, Optics, Cleanroom, Surface roughness, Physics::Accelerator Physics, Spontaneous emission, ddc:530, business, Beam (structure)
Abstract

The European X-ray Free Electron Laser XFEL, a new international research facility, will be built at DESY/Hamburg. The XFEL will generate extremely brilliant and ultra short pulses of spatially coherent X-rays with tuneable wavelengths down to 0.1 nm, and exploit them for revolutionary scientific experiments at various disciplines. The basic process adopted to produce the X-ray pulses is SASE (Self-Amplified Spontaneous Emission). Therefore electron bunches are produced in a high-brightness gun, brought to high energy of about 20 GeV through a superconducting linear accelerator, and transported to up to 250 m long undulators, where the X-rays are generated. The beam vacuum system of the accelerator contains sections operated at room temperature as well as at 2 K in the areas of the superconducting accelerating structures, thus requiring an insulating vacuum system. In addition to standard UHV requirements, the vacuum system for this facility needs to preserve the cleanliness of the superconducting cavity surfaces. Therefore the preparation of all vacuum components for the 1.6 km long main linac includes cleaning of the components in a clean room to remove particles, installation into the accelerator in local clean rooms, and special procedures for pump down and venting. Further challenges are the undulator vacuum chambers filling more than 700 m, where a high surface quality with respect to surface roughness and thickness of oxide layers is mandatory to reduce wake field effects, and the vacuum systems for the various beam dumps, where exit windows acting as vacuum barriers of sufficient reliability need to be developed. In addition, a large amount of about 1.7 km of transport beam lines is required. The layout of the various vacuum sections as well as experience with prototype components will be described.

Published
2008
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9. Measurement of the beam's trajectory using the higher order modes it generates in a superconducting accelerating cavity

Author

Stephen Molloy, N. Baboi, R. Rechenmacher, D. McCormick, L. Piccoli, Josef Frisch, Olivier Napoly, J. May, Tonee Smith, N. Eddy, M. Wendt, Lyudvig Petrosyan, O. Hensler, Claire Simon, R. Paparella, and M.C. Ross

Subjects
Physics, Beam diameter, business.industry, Particle accelerator, DESY, Signal, law.invention, Optics, Nuclear magnetic resonance, law, Nuclear electronics, Physics::Accelerator Physics, M squared, Laser beam quality, business, Beam (structure)
Abstract

It is well known that an electron beam excites higher order modes (HOMs) as it passes through an accelerating cavity. The properties of the excited signal depend not only on the cavity geometry, but on the charge and trajectory of the beam. It is, therefore, possible to use these signals as a monitor of the beam's position. Electronics were installed on all forty cavities present in the FLASH linac in DESY. These electronics filter out a mode known to have a strong dependence on the beam's position, and mix this down to a frequency suitable for digitisation. An analysis technique based on singular value decomposition (SVD) was developed to calculate the beam's trajectory from the output of the electronics. The entire system has been integrated into the FLASH control system.

Published
2007
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10. Beam position monitor calibration at the FLASH linac at DESY

Author

M. Krasilnikov, P. Castro, L. Petrosyan, W. Riesch, N. Baboi, D. Nölle, E. Prat, O. Hensler, T. Traber, and J. Lund-Nielsen

Subjects
Physics, Flash (photography), Nuclear magnetic resonance, business.industry, Calibration, Electrical engineering, Free-electron laser, DESY, Electronics, Radio frequency, business, Beam (structure), Linear particle accelerator
Abstract

In the FLASH (free electron LASer in Hamburg) facility at DESY more than 60 BPMs (beam position monitors) with single bunch resolution are currently installed, and more are planned for future installation. Their calibration has been initially made by measuring each electronics board in the RF laboratory. However the ultimate calibration of each monitor is made by measuring its response to beam movement. This is a time- consuming procedure depending on the availability and accuracy of other components of the machine such as steering magnets. On the other hand it has the advantage of getting in one measurement the answer of the monitor with all its components and of being independent of the monitor type. The calibration procedure and particularities for various types of BPMs in various parts of the linac will be discussed. A procedure based on orbit response measurements is also now under study. This would significantly speed up the calibration procedure, which is particularly important in larger accelerators such as the European XFEL (X-ray free electron laser), to be built at DESY.

Published
2007
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11. Electronics and Algorithms for HOM Based Beam Diagnostics

Author

N. Eddy, Tonee Smith, S. Nagaitsev, O. Hensler, Josef Frisch, J. May, Claire Simon, R. Paparella, Olivier Napoly, Marc Ross, Stephen Molloy, Nicoleta Baboi, D. McCormick, and Lyudvig Petrosyan

Subjects
Physics, business.industry, Electrical engineering, DESY, Particle accelerator, Linear particle accelerator, Spectral line, law.invention, Higher order mode, law, Singular value decomposition, Electronics, business, Beam (structure)
Abstract

The signals from the Higher Order Mode (HOM) ports on superconducting cavities can be used as beam position monitors and to do survey structure alignment. A HOM‐based diagnostic system has been installed to instrument both couplers on each of the 40 cryogenic accelerating structures in the DESY TTF2 Linac. The electronics uses a single stage down conversion from the 1.7 GHz HOM spectral line to a 20MHz IF which has been digitized. The electronics is based on low cost surface mount components suitable for large scale production. The analysis of the HOM data is based on Singular Value Decomposition. The response of the OM modes is calibrated using conventional BPMs.

Published
2006
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12. High Precision Superconducting Cavity Diagnostics with Higher Order Mode Measurements

Author

Nicoleta Baboi, O. Hensler, J. May, S. Nagaitsev, Marc Ross, Claire Simon, Josef Frisch, Tonee Smith, Stephen Molloy, Olivier Napoly, D. McCormick, R. Paparella, M. Wendt, N. Eddy, and Lyudvig Petrosyan

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Phase (waves), Free-electron laser, Particle accelerator, DESY, Surfaces and Interfaces, law.invention, Dipole, Optics, Amplitude, law, Orbit (dynamics), lcsh:QC770-798, Physics::Accelerator Physics, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, ddc:530, business, Beam (structure)
Abstract

Experiments at the FLASH facility at DESY have demonstrated that the higher order modes induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The axes of the modes can be determined from the beam orbit that produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used to obtain high resolution beam position information, and the phase of the monopole modes to measure the beam phase relative to the accelerator rf. For most superconducting accelerators, the existing higher order mode couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional beam position monitor.

Published
2006
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13. Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator

Author

B Faatz, E Plönjes, S Ackermann, A Agababyan, V Asgekar, V Ayvazyan, S Baark, N Baboi, V Balandin, N von Bargen, Y Bican, O Bilani, J Bödewadt, M Böhnert, R Böspflug, S Bonfigt, H Bolz, F Borges, O Borkenhagen, M Brachmanski, M Braune, A Brinkmann, O Brovko, T Bruns, P Castro, J Chen, M K Czwalinna, H Damker, W Decking, M Degenhardt, A Delfs, T Delfs, H Deng, M Dressel, H-T Duhme, S Düsterer, H Eckoldt, A Eislage, M Felber, J Feldhaus, P Gessler, M Gibau, N Golubeva, T Golz, J Gonschior, A Grebentsov, M Grecki, C Grün, S Grunewald, K Hacker, L Hänisch, A Hage, T Hans, E Hass, A Hauberg, O Hensler, M Hesse, K Heuck, A Hidvegi, M Holz, K Honkavaara, H Höppner, A Ignatenko, J Jäger, U Jastrow, R Kammering, S Karstensen, A Kaukher, H Kay, B Keil, K Klose, V Kocharyan, M Köpke, M Körfer, W Kook, B Krause, O Krebs, S Kreis, F Krivan, J Kuhlmann, M Kuhlmann, G Kube, T Laarmann, C Lechner, S Lederer, A Leuschner, D Liebertz, J Liebing, A Liedtke, L Lilje, T Limberg, D Lipka, B Liu, B Lorbeer, K Ludwig, H Mahn, G Marinkovic, C Martens, F Marutzky, M Maslocv, D Meissner, N Mildner, V Miltchev, S Molnar, D Mross, F Müller, R Neumann, P Neumann, D Nölle, F Obier, M Pelzer, H-B Peters, K Petersen, A Petrosyan, G Petrosyan, L Petrosyan, V Petrosyan, A Petrov, S Pfeiffer, A Piotrowski, Z Pisarov, T Plath, P Pototzki, M J Prandolini, J Prenting, G Priebe, B Racky, T Ramm, K Rehlich, R Riedel, M Roggli, M Röhling, J Rönsch-Schulenburg, J Rossbach, V Rybnikov, J Schäfer, J Schaffran, H Schlarb, G Schlesselmann, M Schlösser, P Schmid, C Schmidt, F Schmidt-Föhre, M Schmitz, E Schneidmiller, A Schöps, M Scholz, S Schreiber, K Schütt, U Schütz, H Schulte-Schrepping, M Schulz, A Shabunov, P Smirnov, E Sombrowski, A Sorokin, B Sparr, J Spengler, M Staack, M Stadler, C Stechmann, B Steffen, N Stojanovic, V Sychev, E Syresin, T Tanikawa, F Tavella, N Tesch, K Tiedtke, M Tischer, R Treusch, S Tripathi, P Vagin, P Vetrov, S Vilcins, M Vogt, A de Zubiaurre Wagner, T Wamsat, H Weddig, G Weichert, H Weigelt, N Wentowski, C Wiebers, T Wilksen, A Willner, K Wittenburg, T Wohlenberg, J Wortmann, W Wurth, M Yurkov, I Zagorodnov, and J Zemella

Subjects
free-electron lasers, soft x-ray, accelerators, Science, Physics, QC1-999
Abstract

Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs—dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.

Published
2016
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