Submillimeter Receiver for Telescope at International Space Station
Investigation and Development of the Direct Detection Receiver System Based on the Superconductive Transition Edge Sensor for the Submillimeter Telescope on the International Space Station
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
- SAT-AST/Astronomy/Space, Aircraft and Surface Transportation
3 Approved without Funding
Russian Academy of Sciences / Institute of Radioengineering and Electronics, Russia, Moscow
- P.L.Kapitza Institute of Physics Problems, Russia, Moscow\nFIAN Lebedev / Astro Space Center, Russia, Moscow
- State University of New York at Stony Brook, USA, NY, Stony Brook\nRuhr Universität Bochum / Institute für Theoretische Physic III, Germany, Bochum\nPhysikalisch-Technische Bundesanstalt / Braunschweig Branch, Germany, Braunschweig\nEuropean Space Agency, The Netherlands, Noordwijk\nTechnical University of Denmark, Denmark, Copenhagen\nDepartement de Recherche Fondamentale sur la Matiere Condensee, France, Grenoble\nArray
Project summaryOne of the most important contemporary space research works being in the preparation is the investigation of the celestial sphere electromagnetic radiation at the submillimeter wave band region (the wave lengths l=1.0-0.1 mm or the frequencies f=300-3,000 GHz). They are expecting the obtaining of valuable abundant information in this wave band region which will make possible to broaden our ideas on the Universe and processes in it. Up to now such investigations were carrying out in narrow-scaled volume because the Earth atmosphere is opaque practically in said wave band region and besides the atmosphere itself emits the noise in this waveband region what is restricting possibilities of the detection of this radiation more significantly.
To overcome mentioned above circumstances they in several countries: USA, countries of the European Union, Japan and Russia are planning space missions with the installation of submillimeter wave band receiving equipment having maximum highest sensitivity at space vehicles with purpose to take out this equipment outside the atmosphere.
As the most celestial sphere objects which submillimeter radiation from being planned for the investigation are continuous and have transverse structure the development and application of two-dimensional receiver arrays being comprised of several thousands single receivers are planned. As narrow band receivers of superheterodyne type so relatively wide band receivers of direct detection type are planned for application in the mentioned above space missions. The direct detection receivers do not need heterodyne pump oscillators. By this reason it is much easier to construct multielement (array) receiving systems on their basis. Besides the observations and measurements of spatially distributed continuous sources the array receiving systems are planned for the application in combination with devices of diffraction grating types or similar to determine spectral distribution of the measured celestial sphere radiation sources.
One of the direct detection receivers (direct detectors) of the submillimeter wave band region having a number of advantages in comparison with other analogous direct detectors is the microbolometer based on the heating of electrons in the superconductive transition edge sensor (TES). The TES is cooling down to superlow temperatures (T@0.3-0.1 K) what reduces strongly a thermal fluctuations in TES material and correspondingly an energy transfer from hot electrons to these fluctuations (phonons) and in final analysis leads to the efficient heating of electrons by d.c. bias and absorbed radiation. The electrodes bringing the d.c. bias and microwave (submillimeter) radiation (signal) to the TES and picking up (reading out) the detected signal from the TES are made of the superconductor providing the Andreev reflection at the boundaries between the TES being in transition state and electrodes what leads to the higher increasing of the electron heating efficiency in the TES. The value of temperature of superconductive transition edge has to be chosen a little bit higher of the stable or stabilized temperature of the using refrigerator (cooler) so that not to allow an unnecessary extra heating of electrons in the TES by the TES operating biasing current and the increasing of electron gas thermal fluctuations connected with this extra heating and consequently extra noise what is reducing receiver sensitivity. Said characteristic temperature is providing by means of the choosing a superconductor thickness of which the TES is made or by means of the fabrication of TES in the form of bi-layer structure “superconductor-normal metal” where the proximity effect takes place. In both cases the reducing of the superconductive transition critical temperature (or transion edge temperature) takes place. The TES is inserting into the electrical circuit with given d.c. bias voltage as the result of what the TES is working in the electro-thermal feed-back mode and the absorbed radiation causes the decreasing of d.c. electric current in bias circuit proportional to the power of absorbed radiation. This decrement of the current does be a detected signal.
The advantages of the direct detection receiver based on the TES revealed by authors of this project proposal during preliminary investigations as well as by other research groups are better (lower) noise equivalent power (NEP) and higher operating speed at the relatively simple receiver construction. Investigations having the purpose to create such receiver are started in USA, Russia and other countries. There are numerous difficulties on the way of these investigations.
To overcome the mentioned above difficulties and realize high receiving system sensitivity the research and developments will be fulfilled in frames of proposed project. The scope of activity corresponding to said research and developments includes nine mutually connected tasks:
Task 1. Investigation of behaviour of the normal as well as the superconducting electrons (Cooper pairs) in the bi-layer thin film structures of sub-micrometer planar size at ultra-low temperatures (Т=0.3-0.1 К). Special attention will be paid to the electron gas interaction with the bias current, the absorbed external sub-millimeter radiation, the thermal vibration (phonons) in the thin film and substrate material and with the surroundings (electrodes) made of the superconductor with the critical temperature much higher than Т=0.3 К.
Task 2. Investigation of the single as well as the multi-element (matrix) electro-dynamic (quasi-optical) structures consisted of the metallic and dielectric components and intended for the transmitting of the sub-millimeter radiation from the input antenna to the mentioned above superconducting microstructures.
Task 3. Investigation of the circuits for read-out and amplification of the signals from the described in the Task 1 TES superconducting micro circuits. Both the single element and the matrix circuits are supposed to be studied.
Task 4. Development of the original electro-optical scanning system for collection and space-time commutation of the signals from the matrix receiver pixels with the following synthesis of the distributed source image.
Task 5. Study of the noise sources in the transition edge sensor: noise in the TES resistance, noise caused by the temperature fluctuations, noise due to the breaking and restoration of the Cooper pairs as well as noise in the read-out and amplification circuits. Determination of the contribution of each of the noise sources into the total noise figure for the purpose of the minimizing the total noise.
Task 6. Investigation of methods of the superconducting micro-structures fabrication using the data obtained while performing the Task 1.
Task 7. Development of the new method to measure the ultra-high sensitivity as well as other receiver’s characteristics, corresponding measuring sub-system design.
Task 8. Studying and classification of the sources of the sub-millimeter radiation on the celestial sphere. Formulating of the requirements for the characteristics of the whole receiving system in single- and multi-element versions.
Task 9. Development of the design-arrangement of the whole receiving system construction considering interrelation of all the components, control and auxiliary sub-systems (bias and temperature control circuits, filters etc.) in 0.3 K ultra-low temperature environment (and in case of sufficient financing will be obtained – the temperature as low as 0.1 K) will be considered) and coupling to the external telescope antenna.
The final result of planned research and developments will be a small-scale prototype of the receiving system (up to ten receiving elements) using which its operating ability as a system will be demonstrated and the characteristics of this system will be measured. The main expecting characteristics of the system are: the single element noise equivalent power (NEP) Ј10-18 W/Hz½ at 0.3 К и Ј10 -19 W/Hz½ at 0.1 K, time constantЈ10-5-10-6s. After the replacing of the laboratory refrigerator for its space board version able to work at non-gravity conditions the prototype can be used for the testing of its operation ability at the International Space Station and other space vehicles. It can be transferred to an industrial organization as the prototype for the constructing and fabrication of the full-scaled receiving system with the number of receiving elements of up to several thousands.
The proposed project is a good possibility for scientists and engineers being earlier employed in the area of military developments to switch their activity towards the peaceful purposes. Among the thirty six project participants the twenty three have been previously employed in the research and developments connected with military applications. In the proposed project all these qualified specialists will be employed for the following tasks: investigation of the electronic processes in the superconductors, development of technological methods for ultra-sensitive micro-bolometers fabrication, design of the microwave components (antennas, quasi-optical transmission systems, microwave transformers and other passive microwave components) of the receiving system, development of the methods for precision measurements of the ultra-weak microwave signals, design of the low frequency circuits on the basis of SQUID amplifiers for read-out of the detected signals.
Foreign collaborators from six organizations gave their consent for exchange by the scientific results corresponding to the subject of the project and for personal contacts between scientists on the seminars, conferences and during visits. Apart from this the Jet Propulsion Laboratory, Pasadena, USA, shown their willingness to measure the TES samples fabricated in IREE RAS in their Laboratory. Moreover the Department of Physics and Astronomy of State University of New-York, Stony Brook, USA, Physikalisch-Technische Bundesanstalt, Braunschweig, Deutschland, the Department of Physics of Technical University of Denmark, Lyngby, as well as Institut fuer Theoretische Physik III den Ruhr-Universitat im Bochum, Deutschland, agree to carry out the joint research provided that each side covers its own expenses. With that end in view the Physikalisch-Technische Bundesanstalt are able to put at the project participants disposal the modern technological facility and the Department of Physics of Technical University of Denmark, respectively, the unique ultra-low temperature refrigerator supplied with the high frequency measuring equipment. The Department de recherche fondamentale sur la matiere condensee, Commissariat a l’energie atomique, France, Grenoble, are able to provide the consulting and necessary help concerning of the using of the ultra-low temperature (down to 0.05 K) refrigerators.