TY - JOUR A1 - Jao, Chun-Sung A1 - Vafin, Sergei A1 - Chen, Ye A1 - Gross, Matthias A1 - Krasilnikov, Mikhail A1 - Loisch, Gregor A1 - Mehrling, Timon A1 - Niemiec, Jacek A1 - Oppelt, Anne A1 - de la Ossa, Alberto Martinez A1 - Osterhoff, Jens A1 - Pohl, Martin A1 - Stephan, Frank T1 - Preliminary study for the laboratory experiment of cosmic-rays driven magnetic field amplification JF - High Energy Density Physics N2 - To understand astrophysical magnetic-field amplification, we conducted a feasibility study for a laboratory experiment of a non-resonant streaming instability at the Photo Injector Test Facility at DESY, Zeuthen site (PITZ). This non-resonant streaming instability, also known as Bell’s instability, is generally regarded as a candidate for the amplification of interstellar magnetic field in the upstream region of supernova-remnant shocks, which is crucial for the efficiency of diffusive shock acceleration. In the beam-plasma system composed of a radio-frequency electron gun and a gas-discharge plasma cell, the goal of our experiment is to demonstrate the development of the non-resonant streaming instability and to find its saturation level in the laboratory environment. Since we find that the electron beam will be significantly decelerated on account of an electrostatic streaming instability, which will decrease the growth rate of desired non-resonant streaming instability, we discuss possible ways to suppress the electrostatic streaming instability by considering the characteristics of a field-emission-based quasi continuous-wave electron beam. KW - Laboratory astrophysics KW - Beam-plasma instability KW - Magnetic field amplification KW - Radio-frequency electron gun KW - Field-emission-based quasi continuous-wave electron beam Y1 - 2019 U6 - https://doi.org/10.1016/j.hedp.2019.04.001 SN - 1574-1818 SN - 1878-0563 VL - 32 SP - 31 EP - 43 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Chen, Ye A1 - Loisch, Gregor A1 - Gross, Matthias A1 - Jao, Chun-Sung A1 - Krasilnikov, Mikhail A1 - Oppelt, Anne A1 - Osterhoff, Jens A1 - Pohl, Martin A1 - Qian, Houjun A1 - Stephan, Frank A1 - Vafin, Sergei T1 - Generation of quasi continuous-wave electron beams in an L-band normal conducting pulsed RF injector for laboratory astrophysics experiments JF - Nuclear instruments & methods in physics research : a journal on accelerators, instrumentation and techniques applied to research in nuclear and atomic physics, materials science and related fields in physics ; A, Accelerators, spectrometers, detectors and associated equipment N2 - We report on an approach to produce quasi continuous-wave (cw) electron beams with an average beam current of milliamperes and a mean beam energy of a few MeV in a pulsed RF injector. Potential applications are in the planned laboratory astrophysics programs at DESY. The beam generation is based on field emission from a specially designed metallic field emitter. A quasi cw beam profile is formed over subsequent RF cycles at the resonance frequency of the gun cavity. This is realized by debunching in a cut disk structure accelerating cavity (booster) downstream of the gun. The peak and average beam currents can be tuned in beam dynamics simulations by adjusting operation conditions of the booster cavity. Optimization of the transverse beam size at specific positions (e.g., entrance of the plasma experiment) is performed by applying magnetic focusing fields provided by solenoids along the beam line. In this paper, the design of a microtip field emitter is introduced and characterized in electromagnetic field simulations in the gun cavity. A series of particle tracking simulations are conducted for multi-parametric optimization of the parameters of the produced quasi cw electron beams. The obtained results will be presented and discussed. In addition, measurements of the parasitic field emission (PFE) current (dark current) in the PITZ gun will be exemplarily shown to distinguish its order of magnitude from the produced beam current by the designed field emitter. KW - Cw electron beam KW - RF gun KW - Booster cavity KW - Laboratory astrophysics KW - Field emission KW - Beam dynamics Y1 - 2018 U6 - https://doi.org/10.1016/j.nima.2018.06.063 SN - 0168-9002 SN - 1872-9576 VL - 903 SP - 119 EP - 125 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rabenalt, Thomas A1 - Richter, Michael A1 - Pöhl, Frank A1 - Gössel, Michael T1 - Highly efficient test response compaction using a hierarchical x-masking technique JF - IEEE transactions on computer-aided design of integrated circuits and systems N2 - This paper presents a highly effective compactor architecture for processing test responses with a high percentage of x-values. The key component is a hierarchical configurable masking register, which allows the compactor to dynamically adapt to and provide excellent performance over a wide range of x-densities. A major contribution of this paper is a technique that enables the efficient loading of the x-masking data into the masking logic in a parallel fashion using the scan chains. A method for eliminating the requirement for dedicated mask control signals using automated test equipment timing flexibility is also presented. The proposed compactor is especially suited to multisite testing. Experiments with industrial designs show that the proposed compactor enables compaction ratios exceeding 200x. KW - Design for testability (DFT) KW - test response compaction KW - X-masking KW - X-values Y1 - 2012 U6 - https://doi.org/10.1109/TCAD.2011.2181847 SN - 0278-0070 VL - 31 IS - 6 SP - 950 EP - 957 PB - Inst. of Electr. and Electronics Engineers CY - Piscataway ER -