Nielsen, E.; Axford, W. I.; Hagfors, T.; Kopka, H.; Armand, N. A.; Andrianov, V. A.; Shtern, D. J.; Breus, T.: The ``Long Wavelength Radar'' on the Mars-94 Orbiter. Advances in Space Research 15, pp. (4)163 - (4)178 (1995)
Honary, F.; Stocker, A. J.; Robinson, T. R.; Jones, T. B.; Wade, N. M.; Stubbe, P.; Kopka, H.: EISCAT observations of electron temperature oscillations due to the action of high power HF radio waves. Journal of Atmospheric and Terrestrial Physics 55, pp. 1433 - 1448 (1993)
Kohl, H.; Kopka, H.; Stubbe, P.; Rietveld, M. T.: Introduction to ionospheric heating experiments at Tromsø - II. Scientific problems. Journal of Atmospheric and Terrestrial Physics 55, pp. 601 - 613 (1993)
Rietveld, M. T.; Kohl, H.; Kopka, H.; Stubbe, P.: Introduction to ionospheric heating at Tromsø - I. Experimental overview. Journal of Atmospheric and Terrestrial Physics 55, pp. 577 - 599 (1993)
Lobachevsky, L. A.; Gruzdev, Y. V.; Kim, V. Y.; Mikhailova, G. A.; Panchenko, V. A.; Polimatidi, V. P.; Puchkov, V. A.; Vaskov, V. V.; Stubbe, P.; Kopka, H.: Observations of ionospheric modification by the Tromsø heating facility with the mobile diagnostic equipment of IZMIRAN. Journal of Atmospheric and Terrestrial Physics 54, pp. 75 - 85 (1992)
Stocker, A. J.; Honary, F.; Robinson, T. R.; Jones, T. B.; Stubbe, P.; Kopka, H.: EISCAT observations of large scale electron temperature and electron density perturbations caused by high power HF radio waves. Journal of Atmospheric and Terrestrial Physics 54, pp. 1555 - 1572 (1992)
Barr, R.; Stubbe, P.; Kopka, H.: Long-range detection of VLF radiation produced by heating the auroral electrojet. Radio Science 26, pp. 871 - 879 (1991)
Dowden, R. L.; Adams, C. D. D.; Rietveld, M. T.; Stubbe, P.; Kopka, H.: Phase and amplitude perturbations on subionospheric signals produced by a moving patch of artificially heated ionosphere. Journal Geophysical Research 96, pp. 239 - 248 (1991)
Leyser, T. B.; Thidé, B.; Derblom, H.; Hedberg, Å.; Lundborg, B.; Stubbe, P.; Kopka, H.: Dependence of stimulated electromagnetic emission on the ionosphere and pump wave. Journal Geophysical Research 95, pp. 17233 - 17244 (1990)
Maul, A.-A.; Rietveld, M. T.; Stubbe, P.; Kopka, H.: Anregung periodischer Magnetfeldschwankungen durch Einstrahlung von amplitudenmodulierten Hochfrequenzwellen in die polare Ionosphäre. Kleinheubacher Berichte 33, pp. 141 - 149 (1990)
Maul, A.-A.; Rietveld, M. T.; Stubbe, P.; Kopka, H.: Excitation of periodic magnetic field oscillations in the ULF range by amplitude modulated HF waves. Annales Geophysicae 8, pp. 765 - 780 (1990)
Stubbe, P.; Kopka, H.: Stimulated electromagnetic emission in a magnetized plasma: A new symmetric spectral feature. Physical Review Letters 65, pp. 183 - 186 (1990)
Derblom, H.; Thidé, B.; Leyser, T. B.; Nordling, J. A.; Hedberg, Å.; Stubbe, P.; Kopka, H.; Rietveld, M. T.: Tromsø heating experiments: Stimulated emission at HF pump harmonic and subharmonic frequencies. Journal Geophysical Research 94, pp. 10111 - 10120 (1989)
Rietveld, M. T.; Stubbe, P.; Kopka, H.: On the frequency dependence of ELF/VLF waves produced by modulated ionospheric heating. Radio Science 24, pp. 270 - 278 (1989)
Barr, R.; Rietveld, M. T.; Stubbe, P.; Kopka, H.: Ionospheric heater beam scanning: A realistic model of this mobile source of ELF/VLF radiation. Radio Science 23, pp. 379 - 388 (1988)
Wright, J. W.; Kopka, H.; Stubbe, P.: A large-scale ionospheric depletion by intense radio wave heating. Geophysical Research Letters 15, pp. 1531 - 1533 (1988)
Barr, R.; Rietveld, M. T.; Stubbe, P.; Kopka, H.: Ionospheric heater beam scanning: A mobile source of ELF radiation. Radio Science 22, pp. 1073 - 1083 (1987)
First Light for Sunrise III: the first tests with real sunlight were successful. The balloon-borne solar observatory should be ready for launch at the end of May.
First icy cold, then midnight sun: at the Arctic Circle, the team will prepare the next flight of the balloon-borne solar observatory - and hopes for solar fireworks.
Astronomical teamwork: By combining data from Solar Orbiter and SDO, a group of researchers has unambiguously determined the magnetic field at the solar surface.
The magnetic field in the solar atmosphere exceeds the geomagnetic field strength by four orders of magnitude. It greatly influences the processes of energy transport within the solar atmosphere, and dominates the morphology of the solar chromosphere and corona. Kinetic energy from convective motions in the Sun can be efficiently stored in magnetic fields and subsequently released - to heat the solar corona to several million degrees or to blast off coronal mass ejections.