22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-6.4.4
COSMIC RADIATION EFFECTS UPON AVIONICS - AN INCREASING HAZARD IN THE NEW MILLENNIUM ?
C. Dyer (1), P. Truscott (1), C. Sanderson (1), B. Colwell (2), A. Chugg (3), R. Jones (3), I. MacDiarmid (4), K. Johansson (5)
(1) Space Department, A8 Building, DERA Farnborough, UK;
(2) Sensors and Avionics Department, A5 Building, DERA, Farnborough, UK;
(3) Radiation Effects Group, Matra Bae Dynamics, Filton, UK;
(4) Bae Military Aircraft, Warton, England
(5) Ericsson SAAB Avionics, Linkoping, Sweden
Keywords: cosmic rays, solar particles, ions, protons, neutrons, single event effects, radiobiological
effects, linear energy transfer, dose, dose equivalent, spacecraft, aircraft, atmosphere, sram, dram.
With the increasing use of microelectronics of
ever diminishing feature size, systems are
becoming increasingly susceptible to single
event effects arising from the highly ionising
interactions of cosmic rays and solar particles.
Such single event effects include soft errors,
involving both single and multiple bits, and
hard errors due to latch-up or burn-out. For
space systems an increasing body of evidence
has accumulated over the last twenty years,
systems have been lost and expensive ground
control procedures have had to be invoked.
Although cosmic-ray effects are now a normal
part of the specification, expensive mistakes are
still made. While the earth’s atmosphere shields
out most of the primary cosmic rays, there is a
build up of secondary neutrons which reach a
maximum at around 60000 feet and are only a
factor of three diminished at 30000 feet. By sea
level there is a further factor 300 diminution. As
a result of this mechanism the radiation hazard
at aircraft altitudes is as severe as in certain
low-earth orbits. During the past ten years
there has been increasing evidence of single
event effects on aircraft electronics as well as in
sea- level systems. At the same time there is new
legislation on the allied problem of the effects
of these neutrons on aircrew and frequent
flyers. The problem is expected to increase as
more low power, small feature size electronics
are deployed in More Electric aircraft. In
addition, the current period of solar maximum
activity following the turn of the millennium is
likely to provide large solar particle events
which can penetrate to aircraft altitudes. A
Cosmic Radiation Effects Working Group has
been established to pool research information
on this problem. The work programme is
described together with some initial results.
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