Threshold Voltage Engineering in GaN-Based HFETs: A Systematic Study With the Threshold Voltage Reaching More Than 2 V
T. Schuldt1, C. Schubert2, M. Krutzik3, L.G. Bote4, N. Gaaloul2, J. Hartwig2, H. Ahlers2, W. Herr2, K. Posso-Trujillo2, J. Rudolph2, S. Seidel2, T. Wendrich2, W. Ertmer2, S. Herrmann5, A. Kubelka-Lange5, A. Milke5, B. Rievers5, E. Rocco6, A. Bawamia8, A. Wicht8, B. Battelier9, A. Bertoldi9, P. Bouyer9, A. Landragin10, D. Massonnet11, T. Lévèque11, A. Wenzlawski12, O. Hellmig12, P. Windpassinger12, K. Sengstock12, W.v. Klitzing13, C. Chaloner14, D. Summers14, P. Ireland14, I. Mateos4, C.F. Sopuerta4, F. Sorrentino15, G.M. Tino15, M. Williams16, C. Trenkel16, D. Gerardi17, M. Chwalla17, J. Burkhardt17, U. Johann17, A. Heske18, E. Wille18, M. Gehler18, L. Cacciapuoti18, N. Gürlebeck5, C. Braxmaier1,5, E. Rasel2
Published in:
Exp. Astron., vol. 39, no. 2, pp. 167-206 (2015).
Abstract:
Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth’s gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species 85Rb/87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2DMOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (814 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.
1 Institute of Space Systems, German Aerospace Center (DLR), Robert-Hooke-Str. 7, 28359 Bremen, Germany
2 Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
3 Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
4 Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Ciències, 08193 Bellaterra, Spain
5 Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM), Universität Bremen, Am Fallturm, 28359 Bremen, Germany
6 School of Physics and Astronomy, University of Birmingham, Birmingham B152TT, UK
7 Institut für Optische Systeme, University of Applied Sciences Konstanz (HTWG), Brauneggerstr. 55, 78462 Konstanz, Germany
8 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
9 Laboratoire Photonique, Numérique et Nanosciences-LP2N Université Bordeaux-IOGS-CNRS: UMR 5298, Talence, France
10 LNE-SYRTE, Observatoire de Paris, CNRS and UPMC, 61 avenue de l’observatoire, 75014 Paris, France
11 CNES - Centre National d’Études Spatiales, 18 Avenue Édouard Belin, 31400 Toulouse, France
12 Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
13 Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, GR-71110 Heraklion, Greece
14 SEA House, Bristol Business Park, Coldharbour Lane, Bristol BS16 1EJ, UK
15 Dipartimento di Fisica e Astronomia and LENS, Università di Firenze - INFN, Sezione di Firenze - via G. Sansone 1, 50019 Sesto Fiorentino (Firenze), Italy
16 Astrium Ltd, Gunnels Wood Road, Stevenage SGI 2AS, UK
17 Astrium GmbH - Satellites, Claude-Dornier-Str., 88090 Immenstaad, Germany
18 ESA - European Space Agency, ESTEC, Keplerlaan 1, 2200 AG Noordwijk, ZH, Netherlands
Keywords:
Atom interferometer, Space technology, Equivalence principle test, Bose-Einstein condensate.
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