lofar - Swedish Institute of Space Physics - Uppsala

Physics in 

Space 

Programme 

LOFAR 

Outrigger in 

Scandinavia 

LOFAR and LOIS 

Next-generation sensor networks and 

radio techniques for probing space 

Bo Thidé 

Swedish Institute of Space Physics, Uppsala 

and 

Dept. of Astronomy and Space Physics, Uppsala University 

and 

LOIS Space Centre, Växjö University 

EISCAT Radar School, Kiruna, 2005

New HF-VHF digital radio system for space radio 

LOFAR 

Low Frequency Array (10– 

240 MHz) 

Test station at Exloo 

operational, full scale 

deployment in progress. 

Final antenna 10–100 times 

more sensitive than any 

existing comparable facility. 

LOIS 

LOFAR In Scandinavia 

Test station near Växjö 

operational, fast fibre 

network, supercomputer 

Transmitter in Hörby 

(Teracom) 

Bo Thidé 2 

EISCAT Radar School, Kiruna,, 2005

Hydrogen radiates at 1420.4 MHz (21 cm) 

Very important source of radiation from space 

Bo Thidé 3 


The Westerbork array of 14 dishes, each 25 m in 

diameter sees nearby 1420.4 MHz (21 cm) objects 

M31 (Andromeda, Local group) 

Bo Thidé 4 


Q1: How to observe 21 cm line radio 

emission from the Epoch of Re-Ionisation? 

M. Rees 

Bo Thidé 5 


The cosmological redshift (z~8-10) Doppler shifts 

the 1420.4 MHz signal into the HF/VHF band! 

Bo Thidé 6 


Predicted EoR spectrum to test Big Bang 

J. Briggs 

Bo Thidé 7 


LOFAR 

Bo Thidé 8 


Bo Thidé 9 


LOFAR will be a very sensitive HF/VHF array 

Bo Thidé 10 


Sensor field 

Fibre data transport 

Central supercomputer 

Integrate LOFAR network 

into regional fibre network, 

sharing costs with schools, 

health centres etc. 

LOFAR 

Phase 1 

- Radio telescope 

- Seismic imager 

- Precision weather 

for agriculture, 

wind energy 

Bo Thidé 11 


LOFAR Initial Test Station (ITS) at Exloo 

Bo Thidé 12 


First LOFAR ITS results 

Bo Thidé 13 


The paradigm 

• Conjuncture of technologies 

• inexpensive environmental sensors 

• high capacity fibre, wireless networks 

• affordable supercomputers 

• Experience with LOFAR project 

• wide-area, large-scale, sensor network in Europe 

– financed through regional/national/structure funds 

– originated in the astrophysics community 

• Issues 

• extension of the concept to ERA activities of FP7 

• radio astronomy as a technology platform driver 

Bo Thidé 14 


LOFAR 

Phase 2 

into 

Lower Saxony, 

Schleswig-Holstein, 

Nordrhein-Westfalen 

Ultimate LOFAR 

to 

Växjö SE 

Cambridge UK 

Potsdam DE 

Nançay FR 

etc 

Bo Thidé 15 


LOIS – The LOFAR Outrigger in Scandinavia 

Bo Thidé 16 


Three orthogonal linear dipole antennas 

probe the 3D electric field vectors 

Bo Thidé 17 


Three orthogonal 

loop antennas 

probe the 3D 

magnetic field 

pseudovectors 

Bo Thidé 18 


LOIS resources 

Supercomputer cluster (SUR grant from IBM) and 

Part of the LOIS Test Station outside Växjö, SE. 

Lars Daldorff, Axel Guthmann and the IBM system 

B.T. and Willem Baan (LOFAR) 

at the LOIS Test Station. 

Bo Thidé 19 


Bo Thidé 20 


LOIS and LOFAR 

Bo Thidé 21 


LOIS first of a series of Science Operation Centres 

Bo Thidé 22 


LOFAR and LOIS concept 

• Combine advances in enabling IT 

• inexpensive environmental sensors 

10.000’s of sensors 

• wide area optical broadband networks 

custom+Géant/Danté+SUNET+... 

• high performance computing 

IBM BlueGene/L, IBM JS20 Clusters, ... 

to sense and interpret the environment in 

innovative ways 

Bo Thidé 23 


LOFAR and LOIS sensors 

Sensor type 

Applications 

LOFAR was 

conceived by the 

astrophysics 

community as a new 

way to build radio 

telescopes 

HF-antenna: 

VHF-antenna: 

Geophones: 

Weather: 

Water: 

Infra-sound: 

astrophysics, ionospheric/magnetospheric physics, 

astro-particle physics 

cosmology, early Universe 

solar effects on Earth, space weather 

ground subsidence 

micro-climate prediction 

gas/oil extraction 

precision agriculture 

wind energy 

precision agriculture 

habitat management 

public safety 

atmospheric turbulence, 

meteors, explosions, sonic booms 

Bo Thidé 24 


Secondary radiation experiment setup 

Bo Thidé 25 


1+2D EM Vlasov-Maxwell simulations 

Magnetised kinetic plasma model of the ionosphere. Pump at k = 0.05 kDebye 

injected for 600 plasma periods. Temporally i 

i 

moving Fourier transforms of E field 

in time (angular frequency; vertical) and space (wavenumber; horisontal) 

provides for the dynamic dispersion curves with colour-coded intensities shown. 

(Click for animation) 


High (UH) frequency region 

Low frequency region 

[Bengt Eliasson, Ph.D. thesis, 2002 + several articles in Phys. Rev. Lett., J. Comput. Phys, …] 

Bo Thidé 26 


LOIS/LOFAR beat-wave excitation model 

Bo Thidé 27 


HF pump frequency dependence 

Pump frequency stepped around 4f ce 

, EISCAT/Heating, Norway 

Bo Thidé 28 



Pump frequency stepped around 7f ce 

, Sura, Russia 

Bo Thidé 29 



Pump frequency swept continuously up and down across 4f ce 

, Sura, Russia 

BUM hysteresis 

HF excited secondary radiation (SEE) as recorded at the radio facility SURA near Nizhniy Novgorod, 

Russia, 1999 when the HF pump frequency was swept across the ionospheric 4 th gyroharmonic 

60 kHz 

Pump 


5340 kHz Bo Thidé 4f ce 

5540 kHz 30 


Secondary ionospheric radiation/SEE pump 

frequency dependence: the big picture 

Sideband spectra for SEE in a stationary state as a function of pump frequency f 0 

. 

Data collected 1996–2005 at the SURA facility. Electron cyclotron harmonics (nf ce 

, 

n=4-7) are shown on the top of the figure. Sideband offset Δf=f SEE 

–f 0 

. 

Bo Thidé 31 


Pump frequency dependent Doppler 

radar returns 

Bo Thidé 32 


SEE diagnostic of Langmuir turbulence 

NCM 

SEE spectrogram for the first 200 ms of 

pumping. Left part: frequency resolution 

δF = 1 kHz, time step between Right 

part: δF = 0.2 kHz, time step 500 μs. The 

black line shows the temporal evolution 

of the reflected HF. September 26, 1998, 

14:52–15:26 LT; f 0 

= 6778 kHz ≈ 5f ce 

. 

Pump power ~ 180 MW. 

B.T. et al., Phys. Rev. Lett., in press, July, 2005 

A sequence of separate SEE 

spectra obtained at different 

times after HF turn-on. 

Conclusions: broadening of 

the spectrum in time; an 

overshoot; appearance of 

fine structure (NC m 

) possibly 

same as the DP feature. 

Bo Thidé 33 


Statistical nature of radiation components 

A statistical analysis of numerous 

secondary radiation (SEE) 

components in their steady state 

has shown that they are all are 

non-sinusoidal and noise-like. 

Roger Karlsson, Ph.D. thesis, September 30, 2005 

Bo Thidé 34 


Polarimetric signatures of the HF pump and secondary radiation 

Poincaré spheres of wave polarisation 

Essentially 2D 

Lie group: SU(2) 

Bo Thidé 35 


3D vector polarimetry and radio imaging 

Bo Thidé 36 


3D polarimetry utilising that E(t,x) is a polar vector and 

B(t,x) an axial vector (pseudovector) 

Bo Thidé 37 


Use EM field symmetries and conserved 

quantities (Noether’s theorem) 

Bo Thidé 38 


EM symmetries (continued) 

Bo Thidé 39 


EM symmetries (continued) 

Bo Thidé 40 


EM beam with spin (circular polarisation) 

No orbital angular momentum (OAM) 

Courtesy and © M. J. Padgett, J. Leach et al., U. Glasgow, UK; Royal Society 

Bo Thidé 41 


Field vectors across an antenna array for a 

radio beam with spin (circular polarisation) 

Phase 0 deg 

B. T. et al., preprint, 2005 

Phase 45 deg 

Bo Thidé 42 


Helical radio beams carry orbital 

angular momentum (OAM) 

B. Thidé et al., preprint, 2005 

Bo Thidé 43 


Field vectors across an antenna array for a 

radio beam with orbital angular momentum 

Phase 0 deg 

Phase 45 deg 

B. Thidé et al., preprint, 2005 

Bo Thidé 44 


EM beams with orbital angular 

momentum (OAM) 

l=+1 

l=+3 

l= -4 

Courtesy and © M. J. Padgett, J. Leach et al., U. Glasgow, UK; Royal Society 

Bo Thidé 45 


OAM as turbulence diagnostic 

Bo Thidé 46 


OAM as a new RF modulation technique? 

Bo Thidé 47 


Cosmic ray radio flash candidates at LOIS (Dec 2004) 

Latest news: 27 Dec, 2004, 

magnetar gamma signatures 

tentatively observed. 

Bo Thidé 48 


Bo Thidé 49 


LOIS transmission tests 

Test transmissions (ionospheric 

interactions, space radar) will be 

made with Radio Sweden’s 

500kW HF transmitters and logperiodic 

antennas at Hörby, 200 

km south of the LOIS test station. 

Will try to include other highpower 

HF transmitters in Europe. 

Bo Thidé 50 


Ultra-High Energy 

Particle Detection 

on the Moon 

Oscar Stål 

Swedish Institute of Space Physics 

Uppsala, Sweden 

To the Moon and Beyond 

2005-09-15 

Bo Thidé 51 


Ultra-High Energy Cosmic Rays 

● CR mostly protons 

● Highest energy observed 

● F ~ E -2.75 up to 10 15 eV 

● After knee steeper, F ~ E -3 

● Origin of UHECR unknown 

● Flux obfuscated by B 

10 20 eV ≈ 16 J proton 

100 km/h Golf ball (!) 

Bo Thidé 52 


Radio methods 

If wavelength is longer, output will be coherent 

P prop. Eprimary^2 

Radio transparent material required 

Askaryan proposed the use of ice, permafrost, very dry rock etc. 

Very dry rock is plentiful on the moon, at E=10^16 eV it becomes opaque 

Neutrino in moon -> Shower -> Emission 

Bo Thidé 53

lofar - Swedish Institute of Space Physics - Uppsala

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