EMP  FINDINGS:  A  Compilation  of  Data  on  Electromagnetic  Pulse  Sources  

 Table  of  Contents  

 I. Introduction  to  EMPs  II. Sources  of  EMPs      

a. ‘Space  Weather’  b. High-­‐Altitude  Electromagnetic  Pulse  (Nuclear)  c. Non-­‐Nuclear  Electromagnetic  Pulse  

i. Flux-­‐Generators    ii. High-­‐Power  Microwaves  

III. Weaponization  and  Protection  IV. Probability  of  Attack  (Analysis)  V. Schematics  of  an  Explosive  Flux  Generator  VI. Glossary  of  Terms  (words  appear  underlined  in  text)  

   

I. The  first  question  that  arises  when  researching  this  topic  is:  what  is  an  EMP?    The   acronym   itself   stands   for   Electromagnetic   Pulse.     What   is   this?     To  answer,  electromagnetism  must  be  defined.    Simplified,  it  is  the  study  of  how  electricity  and  magnetic  fields  interact.    Electromagnetic  force  is  one  of  four  fundamental   forces   from   which   the   laws   of   physics   are   derived.   For   all  intents  and  purposes   this  energy  behaves  as  a  wave.    This   is  similar   to  any  kind   of   wave;   think   dropping   a   rock   into   a   pond,   the   size   of   the   wave   is  dependent   on   the   type   of   rock.     The   size   of   an   electromagnetic   wave   is  dependent  on  the  source  of  energy.  Radio  and  radar  are  two  common  devices  that  operate  using  electromagnetic  waves.      

1    An   EMP   then,   is   a   burst   of   energy   that   occurs   when   a   magnetic   field   is  disturbed,  in  the  form  of  an  electromagnetic  wave.    The  effects  of  an  EMP  are  most  readily  correlated  to  a  direct  lightening  attack.    Weaponization  remains  a   hypothetical   threat   due   to   its   ability   wipe   out   any   electronic   devices   by  interfering  and  overloading  operating  electrical  currents.    The  United  States  has   issued   several   commissions2  to   analyze   the   country’s   preparedness  towards   such   attacks   and   outlining   the   vulnerabilities   of   the   region.    However,   the   commissions   lack   a   thorough   analysis   of   the   likelihood   of   an  attack.    Perhaps   that   is  not   their  purpose,  however,  an  understanding  of  all  possible   disseminations   of   EMP   technology,   as   well   as   a   brief   analysis   of  possible   targets   for   each   type,   would   aide   in   the   understanding   of   this  possible  threat.  

 II. A.    The  first  recorded  occurrence  of  an  EMP  was  not  man-­‐made  at  all.    Rather,  

it   occurred   as   a   solar   flare.     A   solar   flare   is   a   ‘sudden,   rapid   and   intense  variation  in  brightness’  on  the  sun’s  surface,  caused  by  a  build-­‐up  in  magnetic  energy.3      

 Solar  flares,  can,  but  do  not  always,  produce  coronal  mass  ejections  (CME).  A  CME  is  a  cloud  of  solar  particles  and  magnetic  energy,  expelled  from  the  sun  during   the   solar   flare.     The   CME   can   approach   and   interfere   with   the  magnetic   field   of   planets,   including   Earth.     This   results   in   a   geomagnetic  storm.     It   is   these   geomagnetic   storms   that  prove  detrimental   to   electronic  devices.     Affects   of   storms   are   greater   at   higher   latitudes,   due   to   the  curvature   of   the   Earth’s   magnetic   field.     In   1859,   colored   auroras   were  observed   even   at   equatorial   latitudes.     Telegraph   systems   failed   under  normal   operation   conditions,   but   the  machines   could   still   transmit  without  batteries.4    In  1972,  telephone  communication  was  shut  down  in  Illinois  and  in   1989,   a   Canadian   power   generator   was   knocked   out.     This   same   storm  caused  significant  damage  to  transformers  at  a  New  Jersey  power  plant.5    The  energy   of   the   CME   disrupted   the   Earth’s   magnetic   field,   and   because  electricity   and   magnetism   are   inherently   linked,   electronic   failure   results.    The   frequency   of   these   events   can   be   correlated   to   the   solar   cycle.     The  magnetic  poles  of  the  sun  flip  every  11  years;  correspondingly  there  is  more  magnetic  activity  at  different  points  of  the  cycle,  resulting  in  more  solar  flares  (solar  maxima).    National  Oceanic  and  Atmospheric  Administration  (NOAA)  tracks   flares   and  other   energetic  data   from   the   sun.     Scientists  predict   that  May  2013  will  be  solar  maxima,  of  low  to  average  intensity.6      

 Using   data   obtained   from   satellites   and   computer   modeling,   NOAA   and  collaborating   organizations   attempt   to   predict   the   occurrence   of  electromagnetic   disturbances   in   order   to   aid   with   air   travel   and   satellite  operation.    Currently,   a   three-­‐day  window  of  predictions   is   available   to   the  public  (http://www.swpc.noaa.gov/forecast.html).7  

 B.       During   testing   of   nuclear   weapons,   it   was   determined   an   EMP   effect  occurred   upon   the   explosion   event.     When   the   nuclear   device   is   launched  beyond   Earth’s   magnetic   field   (>30   km),   the   effect   of   the   pulse   would   be  spread  the  widest.    The  energy  from  the  explosion  is  released  in  the  form  of  gamma  rays.    Electrons  are  knocked  free  during  collisions  with  atmospheric  particles   (Compton   Effect).     These   electrons   are   deflected   by   the  magnetic  field,  which  causes  the  EMP  response.    The  distribution  of  energy  is  based  on  the  curvature  of  the  magnetic  field  and  thus  is  not  evenly  distributed  over  the  affected  area.  

     This  first  portion  of  High-­‐altitude  EMP  (E1)  is  the  first  of  three  stages.8      The  strength  of  an  E1  pulse  is  dependent  both  on  size  of  the  bomb  and  altitude  of  detonation.     The   higher   the   bomb   goes   off   the  wider   the   effected   area,   the  bigger   the   bomb,   the   stronger   the   pulse.     This   first   pulse   is   the   shortest   of  pulses,  lasting  only  nanoseconds,  but  it  can  do  significant  damage,  exceeding  breakdown  voltages  of  equipment  and  has  the  potential  to  destroy  electronic  equipment  instead  of  merely  disabling  it.    The  picture  below  shows  the  range  of  a  hypothetical  attack.  

   The  second  stage  of  the  pulse,  creatively  named  E2,  is  of  intermediate  length  (no   longer   than  a   second)   and  behaves  much   like   a  direct   lightening   strike  and  is  caused  by  the  gamma  rays  and  neutrons  produced  by  the  weapon.    E3,  the   final   stage   lasts   hundreds  of   seconds.     Electrical   currents   invade  wires,  causing  problems  in  connected  electrical  systems.      During   the   atmospheric   tests   of   nuclear   weapons   in   the   mid-­‐twentieth  century,   EMP-­‐phenomena   were   noted   during   high-­‐altitude   tests   over   the  

Pacific   during   Operation   Fishbowl.     The   detonation   was   400   km   high,   1.4  megatons   of   explosives   and   knocked   out   streetlights   and   telephones   in  Hawaii,  1445  km  away.9    It  is  this  version  of  the  EMP  that  the  US  commission  saw  as  the  greatest  threat.      C.   Before   this   type   of   device   can   be   discussed,   it   is   helpful   to   have   a   brief  physics  lesson  to  understand  where  the  energy  is  coming  from.    As  described  before,   electricity   and   magnetism   are   very   closely   related.   The   most  important  concept  to  take  anyway  from  this  relationship  for  the  topic  at  hand  is   that   if   you   pass   an   electrical   current   (I)   through   a   wire,   it   produces   a  magnetic  field  (B).    The  direction  of  the  magnetic  field  (flux)  is  determined  by  the  direction  of  the  current  (see  diagram  below).      

 

10  Two   sub-­‐classes   of   non-­‐nuclear   EMPs   will   be   discussed.     The   first,   an  explosive-­‐pump   flux   compression   generator   (FCG),   creates   an   artificial  magnetic   field   and   then   disrupts   it,   exploiting   an   artificially   generated  magnetic   field   and   converting   chemical   energy   from   an   explosion   into  magnetic  energy.  By  running  a  current   through  a  solenoid  (coil)  or  straight  wire,   a   magnetic   field   is   generated.     This   magnetic   field   can   then   be  compressed,   often   through   a   high-­‐energy   chemical   explosive.     The   energy  from  the  explosive  is  converted  into  work,  which  is  the  done  on  the  magnetic  field  in  the  form  of  compression.    The  field  compresses  to  its  limit  and  then  all  the  work  (energy)  is  released  in  the  form  of  a  magnetic  pulse.    There  have  been  several  designs  over  the  years,  as  both  the  US  and  the  Soviets  sought  to  harness   this  power  during  the  Cold  War.  A  helical,  explosively  pumped  flux  compression  generator  is  shown  below.      

 It   simple  requires  a  capacitor  (energy  storage),  solenoid  coil   (copper  wire),  inner   conductive   tube   (copper),   an   outer   tube   (pyrex),   high-­‐energy  explosives  and  a  detonation  switch.    Schematic  details  will  be  provided  in  the  appendix.  

 More   recent   research   has   explored   the   possibility   of   High-­‐Powered  Microwaves   (HPM)   to  disrupt   electronic   activity.     These  devices   operate   in  the  microwave   area   of   the   electromagnetic   spectra.     The   simplest   of   these  devices   is   the   Vicator   (virtual   cathode   operator).     This   generator   produces  short   pulses   at   high   power.     HMPs   in   general   have   been   used   in   recent  combat  by  the  US  military,  but  much  of  the  data  on  them  remains  unavailable  due  to  ongoing  development.      Additionally,   high-­‐energy   radio   frequency   weapons   must   be   considered.    These  are  smaller,  more  portable  devices  that  operate  in  the  radio  section  of  the  electromagnetic   spectrum.    However,   these  do  not   require  an  explosive  and  are  readily  available  (http://www.amazing1.com/emp.htm).    

III.   Weaponization   and   Protection:   Due   to   our   increased   dependence   on  technology   as   a   society,  we   have   become  more   vulnerable   to   the   threat   of   attack  from  EMP.    Nuclear  attacks  have  the  potential  to  affect  a  broad  area,  while  the  non-­‐nuclear   EMPs   are   smaller   and  more   transportable.     However,   protection  methods  would  remain  the  same.    The  most  popular  method  of  protection  from  an  EMP  are  versions  of  the  Faraday  Cage.        

     The  ‘cage’  surrounds  the  piece  of  equipment  or  room  (or  person)  with  a  conducting  material  or  mesh.    Once  an  electric  field  (EMP)  is  applied,  the  energy  is  forced  into  the  conducting  materials.    This  causes  a  rearrangement  of  the  charges  in  the  room  in  

the   opposite   direction   of   the   applied   charge.     Positive   charges   are   attracted   to  negative   charges   and   vice   versa.     This   results   in   an   electrical   flow   in   the   room  opposite   to   the   applied   charge   and   the   two   cancel   each   other   out,   resulting   in   no  electrical   field   inside   the   cage,   protecting   electronics.   (Here   is   a   movie   that   may  help:  http://upload.wikimedia.org/wikipedia/commons/f/f3/Faraday_cage.gif  .)  Before  and  especially  after  the  governmental  commissions  in  the  middle  of  the  last  decade,   precautions  have  been   taken   to  protect   individual   pieces  of   equipment   as  well   as   military   operations.     Power   grids,   while   protected   to   some   extent,   still  provide  a  weakness,  especially  in  the  case  of  geomagnetic  storms.    http://www.npr.org/templates/story/story.php?storyId=110997398   provides   an  interactive  view  of  the  expanse  of  power  plants  and  the  electrical  grid  of  the  United  States.  

Areas of Probable Power System Collapse11

The   above   figure   shows   a   modeled   geomagnetic   storm   that   would   center   over  northern   Canada   and   greatly   affect   power   grids   in   the   greater   northeast   (circled  region).    Additionally  and  hypothetically,  any  and  all  of  those  power  plants  could  be  a   target  of   a   localized  attack,   although  a  major   city  would  be  more   likely.    A  non-­‐selective,   nuclear   attack   has   the   potential   to   take   out   the   entire   country   (and   the  important  parts  of  Canada,  see  ranges  below).      

HOB=height  of  blast12  IV.  Analysis  

While  all  these  attacks  are  possible,  one  must  look  at  the  likelihood  that  one  could  be   conducted  without   prior  warning.     A   type-­‐by-­‐type   analysis   of   the   likelihood   of  each  magnetic  event  follows:  1.   Solar   Event:   moderately   likelihood.     There   will   certainly   be  more   geomagnetic  storms  of  varying  magnitudes.    A   large  storm  that  could  affect   the  entire  planet   is  less   likely.   NOAA   estimates   the   occurrence   of   one   of   these   ‘superstorms’   every  hundred   years.   Effected   areas   will   most   likely   be   localized.     There   should   be  approximately   one   hour   advanced  warning   from   satellites   along  with   a   three-­‐day  prediction  window  for  preparation.  2.  Nuclear,  High  Altitude  EMP:   low   likelihood.     In  order   to   implement  what  would  unarguably  be  a  catastrophic  event,  an  organization  would  need  to  be  in  possession  of  missiles  capable  of  launching  a  nuclear  warhead  more  than  30  km  in  the  air,  over  a   specific   location,  while  avoiding  detection.    While   this   is  hypothetically  possibly,  current   political   environments   suggest   that   the   able   nations   are   not   necessarily  willing  3.   Non-­‐nuclear   EMP   (explosive):   low-­‐moderate   likelihood.     The   theory   behind  making  a  flux  compression  generator  is  relatively  simple.    However,  the  mechanics  are  very  precise.    While  one  of  these  weapons  could  easily  target  a  vulnerable  power  plant,   terrorist   organizations   are  unlikely   to  have   the   technological   capabilities   or  access   to   necessary   mechanical   elements   that   comprise   a   successful   large-­‐scale  weapon.     HMPs   were   not   considered,   as   most   of   the   technology   is   widely  unavailable.  4.   Radio   Frequency  Weapons:   moderate-­‐high   likelihood.     Small   versions   of   these  guns  are  available  commercially.    While  targets  are  not  likely  to  be  large  (i.e.  Oceans  11),   smaller   targets  have  already  shown   to  be  susceptible   in   the  past.     In   the  past  they  have  been  used  to  disrupt  banks  computer  networks  (Netherlands),  perpetuate  robberies  (Japan,  Russia)  and  by  Chechen  rebels  to  disable  a  small  Russian  security  system   detail.13     These   weapons   would   not   incapacitate   a   nation,   but   they   can  certainly  inconvenience  businesses  and  other  small  organizations.    V.  Schematics  of  an  FCG  As   an   exercise,   we   wanted   to   know   if   it   was   theoretically   possible   to   build   an  explosive   pump   flux   compression   generator,   the   simplest   of   the   large-­‐scale   EMP  devices.     Below   are   provided   several   schematic   drawings,   along   with   pictorial  representation  of  devices  and  components.    A  discussion   regarding   the  amount  of  energy   needed   to   incapacitate   electronic   equipment   is   included.   The   size   of   FCG  needed  to  preform  the  task  would  be  between  10-­‐200  kg,  is  depending  on  the  scale  of  the  target.    Necessary  Mechanical  Components:  

Figure 14. View of the FCG parts; A – Glass-fibre reinforced stator, B – Armature, C – Crowbar ring, D – Rogowski coil for current measurement mounted at the return conductor, E – Plastic disc to centre the armature inside the stator, F – Connection ring of the inner conductor of the seeding cable to the stator, G – Connection ring for the outer conductor (the braiding) of the seeding cable to the armature.14

Shown above are individual components needed to build the structure of an explosively driven flux compression generator. The ‘stator’ (A) is the chamber that contains the electromagnetically derived field and it is built around B, the ‘armature’ where the explosives are housed. The crowbar ring is linked to the detonator (not shown) and activates during the initial explosion to begin a chain of short circuits (think dominos, but with explosives) that compresses the magnetic field (flux) into a smaller and smaller region.

D is for experimental measurements and wouldn’t be used in an actual device. E, F and G are required for the precise placement of all components, as alignment is a crucial component for success. Relative dimensions are available in the reference found in footnote 14. The high explosives fit inside the armature and the amount needed can be calculated by determining the area inside the armature. Exact numbers for the unassembled device shown above are as follows: stator diameter 53mm, coil length 237 mm, armature diameter of 24 mm and 270 g of high explosives. The capacitor generated 11.2 kA of current, which was amplified to 436 kA (A=amps, the measure of current), delivering 15 MJ/m3 (J=joules), corresponding to 20 kV (V=volts). The range, while not discussed for this particular device, it is likely only meters. However, this has the potential to cause damage, as 10 kV-20 kV can harm buried lines at substations. Personal computers are affected as low as 0.5 kV and power relays can be affected at 3.2 kV. A well-placed attack has the potential to cause damage. However, obtaining all the necessary material, machining equipment and a solid understanding of the physics behind the machine remain the limiting factor to use of this device. Additionally, many power plants and substations protect against even larger attacks due to a perceived threat of nuclear EMP and geomagnetic storms.

VI. Glossary of Terms

Electromagnetic Pulse: an intense pulse of electromagnetic energy

Electromagnetism: the interaction of electrical currents and magnetic fields

Solar Flare: A brief eruption of intense high-energy radiation from the sun's surface, associated with sunspots and causing electromagnetic disturbances on the earth, as with radio frequency communications and power line transmissions

Coronal Mass Ejection: a massive burst of solar wind, other light isotope plasma, and magnetic fields rising above the solar corona or being released into space.

Gamma Rays: Penetrating electromagnetic radiation of shorter wavelength than X-rays (see Figure 1).

Compton Effect: An increase in wavelength of X-rays or gamma rays that occurs when they are scattered

Breakdown Voltages: The breakdown voltage of an insulator is the minimum voltage that causes a portion of an insulator to become electrically conductive.

Flux: The total electric or magnetic field passing through a surface

Solenoid: A cylindrical coil of wire acting as a magnet when carrying electric current                                                                                                                1http://dragonphysics.pbworks.com/w/page/18192425/What%20is%20the%20Electromagnetic%20Spectrum  2  Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack: Executive Report 2004; Report of the Committee to Assess the Threat to the United States from an Electromagnetic Pulse (EMP) Attack: Full Report 2008  3  NASA:  http://hesperia.gsfc.nasa.gov/sftheory/flare.htm  4  NASA:  http://science.nasa.gov/science-­‐news/science-­‐at-­‐nasa/2008/06may_carringtonflare/  5  NASA:  Science  News  http://science.nasa.gov/science-­‐news/science-­‐at-­‐nasa/2008/06may_carringtonflare/  6  http://www.swpc.noaa.gov/SolarCycle/  7  NOAA:  http://www.swpc.noaa.gov/SWN/index.html  8  Longmire,  Conrad  L.  "Justification  and  Verification  of  High-­‐Altitude  EMP  Theory,  Part  1"  LLNL-­‐9323905,  Lawrence  Livermore  National  Laboratory.  June  1986.  9  Defense  Nuclear  Agency.  Operation  Dominic  I.  1962.  Report  DNA  6040F.  (First  published  as  an  unclassified  document  on  1  February  1983.)  Page  227.  10http://en.wikipedia.org/wiki/Right-­‐hand_rule  11  2010  Executive  Commission  Summary:  Electromagnetic  Pulse:  Effects  on  the  U.S.  Power  Grid  12  http://www.futurescience.com/emp.html  13  The  Threat  of  Radio  Frequency  Weapons  to  Critical  Infrastructure  Facilities.    DETO  (Directed  Energy  Technology  Office).  14  Appelgren,  P.  “Experiments  with  and  modeling  of  explosively  driven  magnetic  flux  compression  generators”  KTH  Electrical  Engineering.  Thesis.  Stockholm,  Sweden.