2022, Porteanu, Horia-Eugen, Kaempf, Rudolf, Flisgen, Thomas, Heinrich, Wolfgang

The microwave properties of a number of polymers common in industry are investigated. A cylindrical resonator in the TM012 mode is used. The cavity perturbation method and detailed COMSOL simulations are applied for extracting the complex permittivity as a function of temperature. The results are useful for the design of plastic processing tools by heating with electromagnetic fields. The intrinsic parameters of absorption are derived based on two exponential decays: polarization and Arrhenius dependence of the decay times on temperature.

2021, Klute, Michael, Kemaneci, Efe, Porteanu, Horia-Eugen, Stefanović, Ilija, Heinrich, Wolfgang, Awakowicz, Peter, Brinkmann, Ralf Peter

The MMWICP (miniature microwave ICP) is a new plasma source using the induction principle. Recently Klute et al presented a mathematical model for the electromagnetic fields and power balance of the new device. In this work the electromagnetic model is coupled with a global chemistry model for nitrogen, based on the chemical reaction set of Thorsteinsson and Gudmundsson and customized for the geometry of the MMWICP. The combined model delivers a quantitative description for a non-thermal plasma at a pressure of p = 1000 Pa and a gas temperature of Tg = 650–1600 K. Comparison with published experimental data shows a good agreement for the volume averaged plasma parameters at high power, for the spatial distribution of the discharge and for the microwave measurements. Furthermore, the balance of capacitive and inductive coupling in the absorbed power is analyzed. This leads to the interpretation of the discharge regime at an electron density of ne ≈ 6.4 × 1018 m−3 as E/H-hybridmode with an capacitive and inductive component.

2010, Würfl, Joachim, Wentzel, Andreas, Heinrich, Wolfgang, Meliani, Chafik, Lossy, Richard

[no abstract available]

2022, Wust, Peter, Veltsista, Paraskevi D., Oberacker, Eva, Yavvari, Prabhusrinivas, Walther, Wolfgang, Bengtsson, Olof, Sterner-Kock, Anja, Weinhart, Marie, Heyd, Florian, Grabowski, Patricia, Stintzing, Sebastian, Heinrich, Wolfgang, Stein, Ulrike, Ghadjar, Pirus

Non-temperature-induced effects of radiofrequency electromagnetic fields (RF) have been controversial for decades. Here, we established measurement techniques to prove their existence by investigating energy deposition in tumor cells under RF exposure and upon adding amplitude modulation (AM) (AMRF). Using a preclinical device LabEHY-200 with a novel in vitro applicator, we analyzed the power deposition and system parameters for five human colorectal cancer cell lines and measured the apoptosis rates in vitro and tumor growth inhibition in vivo in comparison to water bath heating. We showed enhanced anticancer effects of RF and AMRF in vitro and in vivo and verified the non-temperature-induced origin of the effects. Furthermore, apoptotic enhancement by AM was correlated with cell membrane stiffness. Our findings not only provide a strategy to significantly enhance non-temperature-induced anticancer cell effects in vitro and in vivo but also provide a perspective for a potentially more effective tumor therapy.

2020, Liero, Armin, Klehr, Andreas, Knigge, Andrea, Heinrich, Wolfgang

This paper presents a pulse-laser source for the generation of ps and ns laser pulses with more than 50 W peak output power. The final stages of the drivers use GaN transistors and are capable of switching currents of 0.8 A with 200 ps minimum pulse width and 50 A with 3 ns minimum pulse width. The pulses can be externally triggered by ECL logic. Both single-pulse and pulse train modes are possible.

2014, Al-Sawaf, Thualfiqar, Jensen, Thomas, Heinrich, Wolfgang

Radarbasierte Sensoren im Millimeterwellen-Frequenzbereich bieten hohe Auflösung und gute räumliche Lokalisierung und sind daher als bildgebende und zielverfolgende Sensoren in zukünftigen Raumfahrtprojekten interessant. Dazu ist es notwendig, Ausgangsleistungen um 20 dBm im Frequenzbereich von 70 bis 100 GHz bei gutem Wirkungsgrad bereitzustellen. Mit den verfügbaren Halbleitertechnologien für integrierte Schaltungen (MMICs) ist dies nur eingeschränkt möglich. Deshalb wurde im Rahmen des Vorhabens eine vorhandene Indium-Phosphid-basierte Heterobipolartransistor –Technologie, die das Transfer-Substrat-Prinzip nutzt, auf diese Anforderungen hin weiterentwickelt. Die Arbeiten umfassten zunächst die Stabilisierung des Prozesses sowie die Verbesserung der nichtlinearen Transistormodellierung für den interessierenden Frequenzbereich. Auf dieser Basis wurden Multi-Finger-Transistoren entwickelt, um die Leistungsausbeute pro Einzelelement zu erhöhen. Dazu mussten u.a. neue Designs mit Ballastwiderständen eingeführt werden, um thermisch bedingte Instabilitäten zu verhindern, gleichzeitig aber die Grenzfrequenzen möglichst wenig zu reduzieren. Die damit realisierten W-Band-Verstärker erzielen Ausgangsleistungen bis über 19 dBm und belegen die Eignung des Prozesses für die betrachteten Anwendungen.

2020, Hossain, Maruf, Stoppel, Dimitri, Boppel, Sebastian, Heinrich, Wolfgang, Krozer, Viktor

A fundamental up-converter with high linearity is presented, realized as full Gilbert cell (GC) mixer using a 800 nm transferred substrate (TS) InP-DHBT technology. The LO input of the Gilbert cell conducts from 75 to 100 GHz and requires 5 dBm of input power. The GC attains a single sideband (SSB) conversion gain of 10 ± 1 dB within the frequency from 82 to 95 GHz with a saturated output power of -1 dBm at 86 GHz and >5 dB conversion gain between 75 and 100 GHz. The up-converter exhibits 25 GHz of IF bandwidth. The DC power consumption is only 51 mW. © 2020 The Authors. Microwave and Optical Technology Letters published by Wiley Periodicals, Inc.

2020, Klute, Michael, Porteanu, Horia-Eugen, Stefanovic, Ilija, Heinrich, Wolfgang, Awakowicz, Peter, Brinkmann, Ralf Peter

Radio frequency driven plasma jets are compact plasma sources which are used in many advanced fields such as surface engineering or biomedicine. The MMWICP (miniature micro wave ICP) is a particular variant of that device class. Unlike other plasma jets which employ capacitive coupling, the MMWICP uses the induction principle. The jet is integrated into a miniature cavity structure which realizes an LC-resonator with a high quality factor. When excited at its resonance frequency, the resonator develops a high internal current which—transferred to the plasma via induction—provides an efficient source of RF power. This work presents a theoretical model of the MMWICP. The possible operation points of the device are analyzed. Two different regimes can be identified, the capacitive E-mode with a plasma density of ne ≈ 5 × 1017 m−3, and the inductive H-mode with densities of ne ⩾ 1019 m−3. The E to H transition shows a pronounced hysteresis behavior.