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HPEM (high power

electromagnetic)

threats and immunity test

methods

Nicolas Mora, Werner Hirschi

September 5 2016

Natural <-> man made HPEM threats

Natural

Lightning strikes

Geomagnetic storms

Electrostatic discharges

Man made

Nuclear Electromagnetic pulse (NEMP)

Non nuclear EMP : narrowband and wide

band electromagnetics sources

2

Lightning strikes

Direct or indirect lightning

Threat regarding to helicopters, airplanes,

infrastructure, electronic equipment,

missiles, ammunition,….

3

Geomagnetic storms

Caused by a solar wind shock wave

and/or cloud of magnetic field which

interacts with the earth’s magnetic field

Induces high currents on long lines

(hundreds of A)

4

ESD

5

Charging by

air friction of rotor blades

and airfoils

ion emission from the engine

charged particles in air (rain,

snow, dust)

Voltage: up to 300 kV

Man made electromagnetic threats

6

HEMP

Narrowband

Source: IEC 61000-2-13

Wideband

Man made electromagnetic threats

Identified threats

7

Source: IEC 61000-4-36

Man made electromagnetic threats

Examples of man made HPEM sources

8 Source: IEC 61000-4-36

Hyperband Mesoband Hypoband

Man made electromagnetic threats

Hyperband

9 Source: IEC 61000-4-36

Hyperband Mesoband Hypoband

Man made electromagnetic threats

Mesoband

10 Source: IEC 61000-4-36

Man made electromagnetic threats

Hypoband

11 Source: IEC 61000-4-36

Example of narrowband HPEM source

12

Source: http://www.globalsecurity.org/military/library/report/1996/apjemp.htm

Flux Compression Generator (FCG)

13

Generated current: several tens of Mega-Amps

Virtual cathode radiator (Vircator)

14

Source for

high voltage

pulsesC

ath

od

e

An

od

e

Vir

tua

l

ca

tho

de

Electro-

magnetic

wave

Die

lec

tric

ma

teri

al

Resonant cavity under vacuum

Vircator

Example of HPM test setup using a vircator

15 Source: Montena - Armasuisse, Switzerland

Examples of UWB sources

Portable UWB sources

16 Source: Diehl, Germany

High power UWB source

High voltage (kV to MV) pulses with very

short rise time (some hundreds of ps)

17

1 MV / ~ 200 ps rise

Radiated Field :

~ 62 kV/m at 85 m

New ideas

18

NATO car device vows to stop suicide bombers, available in

http://www.cnet.com/au/news/nato-car-device-vows-to-stop-suicide-

bombers/

Typical UWB test system

Fast pulser + HIRA antenna

19

30 kV / ~ 100 ps rise time

Radiated Field :

< 1 kV/m at 50 m

Typical UWB test system

20

Typical UWB test system

21

Nuclear Electromagnetic Pulse (NEMP)

22

Explosion in an altitude of

several hundreds of km

Gamma ray impulse

Compton effect in the stratosphere

(and other effects)

Emission of an electromagnetic pulse

Irradiation of an area with a diameter of

several hundreds of km on earth

The pulse emission can be

divided in:

Early time: fast rise time /

high amplitude / low energy

Intermediate time: moderate

rise time / amplitude / energy

Late time: slow pulse / low

amplitude / high energy

Typical measured NEMP

NEMP phenomena

23

EM pulse definition as per standard

Pulses definition according to IEC 61000-2-9

24

Coupling on systems / sub-systems

25

Pulse type

Standardized

Waveform

(MIL-STD)

Subsystem

or device

Short line

1 – 10 m

Middle line

10 m – 10 km

Very long line

10 – 5’000 km

Enclosure Lines

Early time

(nanosecond range)

2 / 23 ns or

20 / 550 nsEffect Effect Effect Effect

Intermediate time

(microsecond range)1.5 µs / 5 ms No effect No effect Effect Effect

Late time

(seconds range)0.2 / 25 s No effect No effect No effect Effect

NEMP effect on equipment

Coupling on lines (and antennas)

Coupling on enclosures

26

Subsystems or stand alone systems

Typical standalone systems and

subsystems

System directly exposed to EMP threat

Radiated susceptibility of the subsystem

to E1 pulse

27

Radiated susceptibility test RS105

Test at threat level in a

NEMP simulator

MIL STD 461, RS105

Fast E-field pulse

Rise time : 2.3 ns

Duration : 23 ns

Intensity : 50kV/m

Test all orthogonal polarisations

At least 5 pulses

28

Radiated susceptibility test RS105

Example of NEMP test system as proposed in

MIL STD 461

29

Radiated susceptibility test RS105

Typical NEMP simulator for subsystem tests

30

3.6m high RS105 test system with a 230kV pulse generator

installed on an open area test site

Distributed

Termination

load

HV

generator

Radiating

line

Ground

planeDerivative

field sensor

Radiated susceptibility test RS105

Typical NEMP simulator for subsystem tests

31

indoor 2.7m high RS105 test system with a 170kV pulse generator

32

7.2 m high radiation line

Approx. EUT size: 5 x 3.5 x 3 m (L x W x H)

Indoor or outdoor installation

Mobile NEMP simulator (7.2 m)

7.2 m

Up and ready

in less than 3 h

Radiated susceptibility test RS105

Example of larger NEMP simulator system level tests

33

9 m high RS105 test system with a

800kV pulse generator

Electromagnetic field pulse propagation

34

What about cables?

35

What about cables?

Split the test in two parts :

Radiated susceptibility tests

Conducted susceptibility tests

Intrasite and intersite cables couple with

E1, E2 (and E3)

Protections are installed at each electrical

entry point and shall be tested according

to MIL STD 188-125, appendix 2 : Pulse

Current Injection

36

MIL STD 188-125, PCI

37

MIL STD 188-125, PCI

Pulse definition and injections levels

38

MIL STD 188-125, PCI

Acceptable residual current levels

39

MIL STD 188-125, PCI

Acceptable residual current levels

MIL STD 461, CS116

to test the equipment40

MIL STD 188-125, PCI

Example of needed test equipment

41

Short pulse generator 1 – 5 kA

Short pulse generator 0.1 – 1.3 kA

Intermediate pulse generator

Charge line pulser

Coupling devices

E3 test for intersite cables?

Example of test setup for E3

42

E3 test for intersite cables?

Very expensive test

Only affects long lines -> high voltage

power grid.

Better approach with modelling and

simulations.

To be considered together with power grid

switching issues and possibly

geomagnetic storms threat.

43

44

Test of large systems

On going project for a 25m high, 140m long NEMP simulator

with a 2MV pulse generator

Test of large systems

Build very large EMP simulator ! ?

45 Trestle in the USA : largest ever built EMP simulator

Test of large systems

Usually impossible to test whole system

at threat level

Test at lower level

Measure currents

and field on each

sub system

Interpolate to get

threat level for each

subsystem

Test each subsystem

accordingly46

Test of fix systems

Bring the simulator to the test site ! ?

47 MEMPS : 25 m high mobile EMP simulator

Test of fix systems

Usually impossible to expose fix

equipment of system to EMP threat

Perform CW shielding effectiveness test.

Perform PCI for electrical entry points

Validate with a CWI (continuous wave

immersion) test in frequency domain

48

CWI test

Test setup as proposed in MIL-STD 188-125

49

CWI test

1. Excite the EUT at level measured by the referencesensor : Filluminating(jw)

2. Measure the fields, currents or voltages inside the shelter : Finternal(jw)

3. Build the transfer function : A(jw) = Finternal(jw)/Filluminating(jw)

4. Take analytical form of total field HEMP excitation : Fthreat(jw)

5. Convolve with the transfer function to get the inside threat : S(jw) = A(jw)*Fthreat(jw)

6. Get the threat in time domain using inverse FFT : s(t)

50

Non nuclear EMP : already a fact

In spring 2003, stories leaked to the press

suggested that the Pentagon, after decades of

research, had finally deployed such a device in Iraq.

And when news footage showed a U.S. bomb

destroying an Iraqi TV station, many informed

onlookers suspected it was an electromagnetic “e-

bomb.”

51

Non nuclear EMP : already a fact

52

Already a fact

Public literature has reported criminal usages of electromagnetic tools:1. In Japan, criminals used an EM disruptor to interfere with the computer of a

gaming machine and falsely triggered a win.

2. In Kizlyar, Dagestan, Chechen rebel command disabled police radio communication using RF jammers during a raid.

3. In St. Petersburg, a criminal used an EM disruptor to disable a security system of a jeweller store. The reports mentioned that building the EM disruptor posed a technological challenge similar to assemble a home microwave oven.

4. In multiple European cities (e.g. Berlin) criminals used GSM-Jammers to disable the security system of limousines.

5. In London, UK, a city bank was the target of a blackmail attempt whereby the use of EM disruptors was threatened to be used against the banks IT-system.

6. In Russia, Chechen rebels used an EM disruptor to defeat a security system and gain access to a controlled area.

7. In the Netherlands an individual disrupted a local bank IT network because he was refused loan. He constructed a briefcase-size EM disruptor, which he learned how to build from the internet. Bank officials did not realize that they had been attacked or what had caused the disruption until the assailant was caught.

8. In Moscow, the normal work of one automatic telephone exchange station has been stopped as a result of remote injection of a voltage in to a telephone line. As a result two hundred thousand people had no phone connection for one day

53 Source: www.ursi.org/proceedings/procga11/ursi/E03-9.pdf

Conclusion

Immunity assessment to HPEM of subsystems or mobile small-medium size systems is quite simple

Assessment of large systems against HPEM requires : An system analysis and identification of each

subsystem

An specification of the threat level for each subsystem (by analysis, CWI or low level exposure)

An assessment of the susceptibility of each subsystem at specified exposure level.

54

Thank you for your attention !

55