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MOP006 |
Coherent Accelerator-based High Field THz Radiation at FLASH II |
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- T. Golz, V. B. Asgekar, B. Faatz, G. Geloni, N. Stojanovic, M. Tischer, P. Vagin, M. Vogt
DESY, Hamburg, Germany
- M. Gensch
HZDR, Dresden, Germany
- P. Vobly
BINP SB RAS, Novosibirsk, Russia
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Funding: BMBF grant no. 05K10CHC + 05K10KEB + 05K12CH4
Linear accelerator based light sources with their tunable broad spectral range (THz to hard X-rays regime) and their ability to generate ultra-short pulses with peak intensities many orders of magnitude higher then synchrotron sources, gave rise to a new field of ultrafast physics. In the THz range, the ability of 4th gen. light sources to generate pulses with e-field strengths up to 1 GV/m opened the door to the field of non-linear THz spectroscopy and THz-controlled material science. The main advantage of accelerator-based THz is its scaleability. As the process is not bound to a particular medium, but occurs in the accelerator vacuum, it bypasses the limitation of table top sources. In addition, it has been demonstrated that coherent THz radiation can be generated along femtosecond X-ray pulses in 4th Generation X-ray Light sources such as FLASH [1,2,3] and LCLS [4]. This opens up the opportunity for naturally synchronized THz pump X-ray probe experiments on a few femtosecond time scale [1,2,4]. Here we present the design for the THz source at FLASH2, which takes new findings [5] and challenges into account that we face during the radiation transport to the experimental hall.
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THA04 |
Optical Afterburner for Naturaly Synchronized Pump-probe Experiments at FLASH |
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- N. Stojanovic, A. Al-Shemmary, D. Espeloer, T. Golz, R. Riedel, E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany
- M. Foerst
CFEL, Hamburg, Germany
- M. Gensch
HZDR, Dresden, Germany
- F. Tavella
HIJ, Jena, Germany
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Funding: German Federal Ministry for Education and Research, project 05K10CHC and 05K12CH4
We employ so- called Optical Afterburner [*,**] principle to generate optical replica pulses of X-ray pulse at FLASH (Free Electron LASer in Hamburg). These pulses are naturally synchronized to the FEL pulses and share the same envelope and arrival time, with accuracy down to few femtoseconds. Because of this, Optical Afterburner pulses can be used for complete temporal diagnostics for FEL pulses. Because we shift diagnostics challenge from X-ray to visible range, this significantly simplifies detection. During pulse- duration measurement campaigns at FLASH, Optical Afterburner has been demonstrated as versatile and accurate tool to measure pulse duration of X-ray FEL pulses. In the most recent development we have amplified, Optical Afterburner pulses by three orders of magnitude and will used it in the X-ray/Visible pump-probe experiments for ultimate temporal resolution. We have demonstrated amplification concept at FLASH, where we reach pulse energies above 1uJ at 1MHz repetition rate.
References:
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 030701 (2010)
* Proceedings of IPAC2011, San Sebastián, Spain. THPC084
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THP065 |
Towards a Novel THz-based Monitor for Subpicosecond Electron Bunches Working at MHz Repetition Rates and Low Bunch Charges |
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- B.W. Green, M. Gensch, S. Kovalev
HZDR, Dresden, Germany
- A.S. Fisher
SLAC, Menlo Park, California, USA
- T. Golz, N. Stojanovic
DESY, Hamburg, Germany
- M. Kuntzsch
TU Dresden, Dresden, Germany
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The control and measurement of electron bunch properties at the femtosecond (fs) level has become an important field in modern accelerator physics, in particular since these became crucial parameters for the operation of 4th Generation X-ray Light-sources. In order to operate modern-day photon factories such as LCLS and the future European X-FEL reliably, a number of novel approaches have been developed that allow the noninvasive measurement of electron bunch form and arrival time. Some of those are based on the electro-optic detection of the coulomb field of the electron bunches in the electron beamline; some detect the super-radiant THz pulses from the electron bunch. However, none of these concepts allows for pulse-to-pulse detection on a quasi-CW accelerator operating at the MHz repetition rates planned for the next generation of X-ray free electron lasers. In this contribution we present first results from a new monitor concept, based on the single-shot electro-optic detection of super-radiant THz pulses, that has the potential to operate at MHz repetition rates.
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Poster THP065 [1.966 MB]
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| THP069 |
Performance Study of High Bandwidth Pickups Installed at FLASH and ELBE for Femtosecond-Precision Arrival Time Monitors |
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- M.K. Czwalinna, C. Gerth, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
- A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
- M. Gensch, M. Kuntzsch
HZDR, Dresden, Germany
- M. Kuntzsch
TU Dresden, Dresden, Germany
- T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
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At today's free-electron lasers, high-resolution electron bunch arrival time measurements have become increasingly more important in fast feedback systems for a timing jitter reduction down to the femtosecond level as well as for time-resolved pump-probe experiments. This is fulfilled by arrival time monitors which employ an electro-optical detection scheme by means of synchronised ultrashort laser pulses. Even more, at FLASH and the European XFEL the measurement has to cover a wide range of bunch charges from 1 nC down to 20 pC with equally sub-10 fs resolution. To meet these requirements, recently a high bandwidth pickup electrode with a cut-off frequency above 40 GHz has been developed. These pickups are installed at the macro-pulsed SRF accelerator of the free-electron laser FLASH and at the macro-pulsed continuous wave SRF accelerator ELBE. In this paper we present an evaluation of the pickup performance by direct signal measurements with high bandwidth oscilloscopes and by use of the electro-optical arrival time monitor.
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