Turkish delights and harsh environments

-December 02, 2014

Earlier this year, I had the good fortune of going on holiday to Turkey with my family. One day, while lying by the pool absorbing some charged particles and reading the latest edition of EDN, I was approached by a 'gentleman' from the hotel's spa whose pitch was, "How would you like me to bathe you better than your mother has ever washed you?" I'm a simple country boy from mid Ulster and was absolutely stunned! Call me old fashioned, but such a proposition could get you into serious trouble in many places if you know what I mean. Somehow and without any control on my part, my subconscious blurted, "No thank you."

The next day the same gentleman, Yaman, returned with a similar offer. This time, my wife and father-in-law who were also present this time, got in the act and took great delight in booking a 'treatment' for me for the following day.

The next morning at breakfast I bumped into Yaman and nervously said, "Good Morning." His only and immediate response was, "Today, I will wash you," which simply made me more anxious.

At 10:00 A.M., my family took me to the spa where we were all greeted by Yaman - I must confess that I was feeling just a tad uncomfortable at this point. Yaman introduced me to his colleague and said, "She will take good care of you," and disappeared - I never saw Yaman again!

The receptionist led me to a Turkish bath and introduced me to her colleague, Bulent, a big, burly lad with a simple sheet wrapped below his midriff as depicted in Figure 2. For those of you not familiar with the concept of a Turkish bath, and that included me, this involves lying on a marble pedestal and being washed and massaged using LOTS of water - apparently this tradition dates back to Roman times.


Figure 1: A Turkish bath.

The four-part 'treatment' started with me being smothered and bathed in ground coffee - I don't even like coffee! Bulent has a brush in his hand that resembled and felt like a very rough Brillo pad that was used to exfoliate my body - I now know how a saucepan feels!

The ground-coffee wash was followed by a foam bath as shown below:


Figure 2: Ground-coffee exfoliation and a foam bath (that's not me by the way!).

After this, I was escorted to a dark holding room with gentle pan-pipe music playing in the background and pictures of Vestal Virgins painted on the walls. I couldn't help but notice that there were four people lying on couches with their faces plastered with something that looked like mud.

I was told to lie on a couch and relax, given a glass of water, and after ten minutes, I was approached by a lady with a pot of green goo, "Seaweed-extract face mask sir." Without being given any chance to respond, she started lathering the stuff all over my face.

Twenty minutes later I was ushered to a washing area and told to remove the seaweed extract, before being escorted to another room for a massage. This I enjoyed, after running around a tennis court every Saturday morning, this was just the thing to prepare for the season ahead.

As sad as I am, perhaps it was the effects of several days of sunbathing (and/or the ground coffee), the thing that came to my mind during the spa 'treatments' were the hazards of space for electronics.

The harsh environment of space can wreak havoc on unprotected microelectronics, e.g., continued exposure to energetic particles gradually degrades device performance, ultimately leading to component failure. Cosmic rays speeding through space can strike ICs at sensitive locations, causing immediate upsets known as SEEs. Heavy ions, neutrons, and protons can scatter the atoms in a semiconductor lattice, introducing noise and error sources.

The space-radiation environment produces a multitude of trapped, solar, and cosmic-charged particles that affect microelectronic devices. Terrestrial magnetic fields and interplanetary space contain electrons, protons and heavy-ions, which are harmful to spacecraft electronics.

The primary sources of ionizing radiation are:

  1. The Sun in the form of a high-speed, solar wind of charged particles emanating from its corona, which includes electrons, protons and heavy ions.
  2. Charged particles from the solar wind which get trapped in the Earth's magnetic field.
  3. Heavy ions from galactic, cosmic-rays.

The Sun's cycle periodically generates increased levels of transient, ionizing radiation, e.g., coronal-mass ejections associated with magnetic storms produce elevated levels of protons, while solar flares spew out extra heavy-ions. These charged particles travel towards Earth in the form of a hot, ionized gas known as the solar wind, interacting with our planet's magnetic field to form a magnetosphere as shown below.


Figure 3: Earth's magnetosphere (image courtesy of NASA, ESA and SOHO).

The magnetosphere deflects a majority of the charged particles, but a percentage get trapped within magnetic regions around our planet known as the Van Allen belts. Some drift to lower altitudes and eventually to Earth's atmosphere where they get absorbed. These include protons, electrons and heavy ions with varying levels of energy and flux, which can increase by many orders of magnitude during key solar events.

The Van Allen belts introduce large variations in the levels of flux of the trapped particles, and due to an offset in our planet's geometric centre, the magnetic field is weaker and hence there are more trapped particles over an area in the south Atlantic Ocean termed the South Atlantic Anomaly. LEO satellites are exposed to high-energy protons in this region above Earth.

The Van Allen radiation belt comprises an inner proton region, which includes LEO, and an outer electron belt. MEO navigation satellites fly through the middle of the Van Allen belts accumulating a lot of ionizing radiation. GEO satellites reside within the outer electron belt but outside the inner region of trapped protons as shown below. GEO spacecraft are also affected by high energy protons generated by solar flares.


Figure 4: Illustration of Van Allen belts and typical satellite orbits (image courtesy of the AIAA).

Radiation damages semiconductors by virtue of its ability to ionize material, e.g., charged particles pass through a CMOS device depositing energy, generating electron-hole pairs. Ionizing particles cause gradual and cumulative, total-dose effects whereas non-ionizing ones are responsible for damage to the actual, semiconductor lattice.

Vacuum is also an inherent feature of space and materials sublime and outgas with ceramic, hermetic packages being used on most missions.

Apparently my skin had a radiant glow after the 'treatments' - I'm not sure if this was due to the seaweed extract or the non-forgiving Turkish sun. Until next month, enjoy your ground coffee!

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