Megaimpulse NPG-10/100k User manual

NANOSECOND PULSE GENERATOR
NPG-10/100k (NPG-10/100kN)
USER MANUAL
v. 1.0
© 2021 Megaimpulse Ltd.

Copyright © 2021 MEGAIMPULSE Ltd. All Rights Reserved.
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intent to inf inge.
Megai pulse Ltd. contact infor ation
Mail add ess: 26 Polytechnicheskaya st ., St. Pete sbu g, 194021 Russia
www: http://www.megaimpulse.com
e-mail: mp@powe .ioffe. ssi. u
fax: [phone]

CONTENTS
Package content ........................................................................................... 2
Gene al view of NPG-10/100k nanosecond pulse gene ato ........................... 2
Safety manual .............................................................................................. 3
Technical specification ................................................................................. 4
F ont and ea panels view ............................................................................ 5
Ope ation desc iption ................................................................................... 6
F ont panel in detail ...................................................................................... 7
Putting the gene ato into ope ation .............................................................. 9
T igge ing of the gene ato ........................................................................... 11
Output SYNC pulse ...................................................................................... 17
Ove heat mode ............................................................................................. 18
Fuse eplacement .......................................................................................... 19
Wa anty ...................................................................................................... 20
Appendix A.
List of p eset epetition ates and numbe of pulses within a bu st ........... 21
User manual o NPG-10/100k (NPG-10/100kN) 1

PACKAGE CONTENT
Please check the package fo the following items:
 NPG-10/100k (NPG-10/100kN) nanosecond pulse gene ato (he einafte
"gene ato ")
 Powe supply cable
 High voltage output coaxial cable
 Use manual
Fig.1. Gene al view of NPG-10/100k (NPG-10/100kN) nanosecond pulse
gene ato .
MEGAIMPULSE LTD. 2

SAFETY MANUAL
Electrical safety
 NPG-10/100k (NPG-10/100kN) pulse gene ato is high voltage equipment.
Please be ve y ca eful and ope ate by qualified pe sonnel only.
 The e is a isk of elect ic shock, st ong elect omagnetic inte fe ence,
damage to the gene ato o othe elect onic equipment in case of imp ope
use.
 Do not switch on the gene ato without p ope g ounding. The g ounding
cable should be connected to the te minal on the ea panel of the gene ato
o a th ee-te minal powe supply outlet with g ound contact should be used.
 It is st ongly p ohibited to switch on the gene ato without an output
coaxial cable. The elect ical a cing on the open coaxial connecto will
damage the gene ato . Please use ou special high voltage coaxial
connecto and cable only. Standa d N-, HN- o 7/3-types connecto s a e not
suitable. High voltage connecto s should be clean and d y, f ee f om dust,
di t and, any obstacles. The mating Teflon pa ts a e lub icated by silicone
g ease.
 When adding o emoving the gene ato to o f om the system, ensu e that
the powe supply ON/OFF switch is tu ned off and/o powe supply cable
is unplugged befo e the output cable is connected o disconnected.
 Please connect o disconnect any equipment, toggle the gene ato f om
inte nal to exte nal t igge ing mode o vice ve sa while the gene ato is in
high voltage OFF state only by HV ON/OFF switch.
Operation safety
 Please ead this manual befo e installing and using the gene ato .
 Befo e using the p oduct, make su e that all cables a e applicable and not
damaged.
 To avoid a sho t ci cuit, please keep metal pa ts like clips, sc ews, and
staples away f om the gene ato .
 The gene ato is designed to wo k in no mal labo ato y conditions. Avoid
dust, humidity, and tempe atu e ext emes. Do not place the gene ato in
any place whe e it may become wet.
 Place the gene ato on a stable su face.
 If you encounte any technical p oblem with the gene ato , please contact
Megaimpulse Ltd. Do not t y to epai the gene ato by you self.
User manual o NPG-10/100k (NPG-10/100kN) 3

TECHNICAL SPECIFICATION OF NPG-10/100k (NPG-10/100kN)
NANOSECOND PULSE GENERATOR
Output pulse amplitude
(typical)
s ooth regulated within 7.0 kV ... 11.0 kV
(50 steps) on atched 75 Oh load;
up to 22kV on open cable and discharge reactor
Output impedance 75 Oh
Output connecto special HV coaxial type connector
Output cable coaxial cable with 75 Oh i pedance,
outer dia eter 9.6
Pulse pola ity positive (NPG-10/100k)
negative (NPG-10/100kN)
Pulse ise time < 4 ns (fast part of output pulse)
Pulse width (FWHM) 7 ns
Pulse ene gy regulated within 5 J ... 10 J (50 steps)
Peak pulse powe up to 1.6 MW
Ope ation modes continuous, burst, single pulse odes;
internal and external triggering
Continuous mode epetition
ates
fro 1 Hz to 10 kHz (internal triggering)
fro single pulse to 10 kHz (external triggering)
Bu st mode epetition ates;
numbe of pulses in bu st
up to 100 kHz; up to 10000 pulses within a burst
or each one second interval
Exte nal t igge ing
(SYNC IN) BNC connector, +2.4V ... +5V a plitude
Inte nal gene ato delay ~ 1 μs
Jitte RMS (typical) 1 ns
SYNC OUT BNC connector, TTL level
Powe supply AC 110-230V, 50-60 Hz
Size 248 х 90 х 250 3
Weight (with cables) 6 kg
MEGAIMPULSE LTD. 4

FRONT VIEW
2 3 4 5
6 7 8 9 10
REAR VIEW
11 12 13
1 – High voltage output coaxial connecto
2 – High voltage ON/OFF push button with ON state LED indicato
3 – Inte nal/exte nal t igge ing push button with LED indicato
4 – F equency and numbe of pulses in bu st 4-digit display
5 – F equency and numbe of pulses in bu st egulation knob with push button
6 – BNC type SYNC OUT connecto
7 – BNC type SYNC IN connecto
8 – Ove heat LED indicato
9 – Output pulse ene gy 2-digit display
10 – Output pulse ene gy egulation knob with push button
11 – Powe supply ON/OFF switch
12 – Powe supply connecto and fuse holde
13 – Fans
14 – G ound te minal
14
User manual o NPG-10/100k (NPG-10/100kN) 5
1

OPERATION DESCRIPTION
NPG-10/100k gene ato is a powe ful and sma t device. In spite of its compact
size and small numbe of cont ol elements it implements a lot of ope ation
egimes and high output powe acco ding to the use demands. Please ead this
manual ca efully to be familia with the basic ope ation p inciples.
 The gene ato has open and sho t load p otection as well as ove heating
p otection. Howeve , it is st ongly p ohibited to switch on the gene ato
without output cable o use less than 3 mete s length output cable.
The gene ato can ope ate in a single pulse, continuous and bu st ope ation modes,
as well as inte nal o exte nal t igge ing. The gene ato ’s cont ol system p ovides
qua tz stabilized t igge ing pulses in continuous and bu st ope ation modes and
p events imp ope t igge ing in case of exte nal t igge ing mode. The complete list
of the p eset f equencies and the p eset numbe of pulses in a bu st a e shown in
Appendix A.
 In all ope ation modes, the minimum pulse-to-pulse inte val is limited to
9.9 µs, which co esponds to 101 kHz epetition ate; the maximum
numbe of pulses within any one-second inte val is limited to 10000.
The efo e, the maximum ope ation f equency in continuous mode is 10
kHz. Highe epetition ates a e available in bu st mode only.
The following ope ation pa amete s can be set by the f ont panel cont ols:
- FREQUENCY f om 1 Hz to 101 kHz, the default value is 100 Hz;
- NUMBER OF PULSES in the bu st (within one-second inte val) f om 1
to 10000, the default value is 1000;
- Output PULSE ENERGY f om 50% to 99%, the default value is 75%.
If the cu ently set epetition ate in Hz is lowe than o equal to the set numbe of
pulses (within one-second inte val) then the gene ato ope ates in continuous
mode, othe wise, it switches into bu st mode automatically. The pe iod of bu sts is
fixed to one second. So, FREQUENCY pa amete sets the time inte val between
pulses, while NUMBER OF PULSES sets the bu st length o numbe of pulses
followed by a pause up to the end of the one-second inte val.
 The FREQUENCY and NUMBER OF PULSES pa amete s wo k as the
limits fo the exte nal t igge ing pulses. The efo e, FREQUENCY sets the
maximum allowable exte nal pulses f equency (minimum inte val between
pulses) and NUMBER OF PULSES sets the maximum bu st length o the
maximum numbe of pulses within each one-second inte val. By the way,
the gene ato ’s cont ol system p events ove loading and damage to the
gene ato in case of imp ope exte nal t igge ing.
MEGAIMPULSE LTD. 6

FRONT PANEL IN DETAIL
Special type coaxial connecto suitable fo HV
nanosecond pulses feeding. Please attach the output
HV cable fi mly befo e tu n-on the gene ato . It is
ve y impo tant to keep HV connecto s clean to p event
unwanted a cing and glow discha ge inside the mating
pai . If necessa y, please clean the connecto s with
cotton bud and alcohol, and then apply a d op of pu e
silicone g ease befo e mating the connecto s. G ease
fills ai gaps and eliminates possible discha ge inside.
Non
-
latching push
button, which
toggles HV system
ON and OFF. Red LED on the button lights on when
HV system is activated and eady fo t igge ing by
inte nal o exte nal t igge ing pulse. HV sets to OFF
state when the gene ato is powe ed on, and
automatically switches to OFF state in case of
ove heating o TRIGGERING TEST mode activation.
Latching push button
,
which toggles inte nal o
exte nal t igge ing modes. LED lights off if the button
is pushed and no exte nal t igge ing pulses a e
applied. LED blinks with 1 Hz f equency in case of
successful exte nal t igge ing. Inte nal t igge ing
mode is activated in the pushing back state. Red LED
on the button lights on and indicates immediate
t igge ing when HV system is activated by HV
ON/OFF button.
Fou -digit LED display and cont ol knob with push-
button, which set FREQUENCY and NUMBER OF
PULSES pa amete s. The FREQUENCY is indicated
in kHz with a decimal dot. Fo example, 1 Hz is
indicated as 0.001; 100 kHz is indicated as 100.0.
Please push the cont ol knob until it clicks and hold it
fo one second to switch into NUMBER OF PULSES
mode. LED display would blink and indicate
NUMBER OF PULSES. Fo example, 1 pulse is
indicated as 0001, 10000 pulses a e indicated in
thousands as 010.0. Please push the cont ol knob and
hold fo one second again to switch back into
FREQUENCY mode. The complete lists of p eset
f equencies and the numbe of pulses a e shown in
Appendix A.
User manual o NPG-10/100k (NPG-10/100kN) 7

Two
-
digit LED display and cont ol knob with push
-
button, which set PULSE ENERGY pa amete . The
ene gy can be adjusted f om 50% to 99% with 1%
step. LED display lights on constantly in idle o
continuous ope ation modes. It blinks in bu st mode,
the du ation of LED light on and off states
co esponds to the duty cycle. Please push the cont ol
knob until it clicks and hold it fo one second to
switch into t igge ing TEST mode. HV ON/OFF push
button is blocked in this mode. LED display shows
00, which means ze o output powe . T igge ing
sequence f om the inte nal o exte nal sou ce goes to
SYNC OUT connecto . This mode allows to test the
t igge ing and see the exact t igge ing sequence
without applying HV pulses to the load. Please push
the cont ol knob and hold fo one second again to
switch back into PULSE ENERGY mode.
If the
i
nte
n
al
tempe atu e exceeds
a
safe
level,
then
OVERHEAT LED lights on, and the gene ato stops
the ope ation. It may occu in case of high ambient
tempe atu e / insufficient cooling o afte long-time
ope ation at high amplitude and high epetition ate.
HV ON/OFF button is blocked while the gene ato is
ove heated. Please stay the gene ato in idle mode, and
allow cooling by the fans fo seve al minutes. The
gene ato will etu n to no mal ope ation
automatically when the tempe atu e dec eases; p ess
HV ON again to continue the ope ation.
BNC input connecto fo exte nal t igge ing pulses.
The amplitude should be +2.4V … +5V, the nominal
pulse width is 1 µs. Exte nal synch onization mode is
activated by p essing INT/EXT g een push button.
BNC output c
onnecto fo SYNC OUT pulses. The
f ont edge of SYNC OUT pulse p ecedes HV output
pulse by ~1 µs. SYNC OUT pulse du ation is 400 ns,
the amplitude is 3V@50Ω.
MEGAIMPULSE LTD. 8

PUTTING THE GENERATOR INTO OPERATION
 Please st ictly follow the desc ibed steps. It helps to p event damage to the
gene ato , othe equipment, and pe sonnel inju y.
Step 1.
Unpack the gene ato and check the p esence into the package of the following
items:
- NPG-10/100k (NPG-10/100kN) gene ato ,
- powe supply cable,
- output 75 Ohm coaxial cable.
Step 2.
Set up the gene ato . G ound it obligato y by connecting g ound cable to te minal
on the ea panel (14) o use th ee-te minal powe supply outlet with g ounding
contact.
Step 3.
Check the output coaxial female connecto on the f ont panel of the gene ato and
co-pai male connecto on the cable. Both connecto s should be clean, f ee f om
dust, di t, and obstacles. Clean the connecto s with alcohol and/o cotton bud if
necessa y. Afte cleaning, please apply a d op of pu e silicone g ease befo e
mating the connecto s. G ease fills the ai gap between co-pai connecto s and
eliminates possible glow discha ge inside.
Attach the cable connecto to the gene ato f ont panel connecto (1). The tight
and fi m contact of the connecto s is impo tant fo the safe ope ation of the
gene ato . Even a small ai gap between the connecto s may esult in a glow
discha ge, a cing, and damage to the gene ato and the cable.
The following p ocedu e is ecommended fo obtaining good and tight contact:
1. Align both connecto s.
2. Hold the gene ato by one hand to p event moving and p ess the cable
connecto by anothe hand towa d the gene ato connecto .
3. Sc ew the cable connecto nut by hand, usually one o two tu ns. Do not
otate the cable connecto body.
4. P ess the cable connecto towa d the gene ato connecto again.
5. Again, sc ew the cable connecto nut one o two tu ns.
6. Repeat steps 4 and 5 up to tight contact. Finally, sc ew the cable
connecto nut fi mly with both hands.
Afte the fi st testing of the gene ato , it is highly ecommended to check whethe
the tight contact of the connecto s is obtained. Unsc ew the cable connecto . It
should be no ozone o bu nt smell f om the connecto s o bu nt t aces.
User manual o NPG-10/100k (NPG-10/100kN) 9

Do not disconnect and connect the high voltage connecto s many times to p event
them f om wea ing and contamination. Silicone g ease is al eady applied to both
connecto s at the facto y. It emains between the mating connecto s fo a ve y
long time and p events discha ge inside.
Step 4.
Connect anothe side of the coaxial cable to the load. The Teflon cone insulato is
installed on the cable end to p event the ba ie discha ge between the cent al wi e
and the cable b aid ac oss the cable solid polyethylene insulato (See Fig.2). You
may use additional wi es fo connection to the load. Solde the high voltage load
contact to the cent al cable wi e and sc ew/solde g ound load contact to the
g ound cable clamp. Please keep the length of the wi es between the coaxial cable
and the load as sho t as possible.
 Mo e than 10 cm additional wi es between the load and the coaxial cable
esult in excessive st ay inductance and significantly dec ease the pulse
amplitude on the load.
Fig.2. Teflon cone insulato on the cable end.
MEGAIMPULSE LTD. 10

 The length of the output coaxial cable is 3 mete s. Using the sho te coaxial
cable may esult in damage to the gene ato .
Step 5.
Connect powe supply cable to the wall powe outlet.
Switch on the gene ato by the toggle powe switch on the ea panel. The inte nal
fans should sta t to otate.
Step 6.
Push back INT/EXT push button (if it is p essed) in INT position. Red LED on the
button should light on indicating the inte nal t igge ing mode.
Set the equi ed f equency, the numbe of pulses, and the ene gy by the knobs. It
is cleve to sta t the expe iments with low ope ation pa amete s, which helps to
p event possible damage to the equipment in case of any e o o imp ope using.
P ess HV ON/OFF push button. Red LED on the button would light on, and
output HV pulses would go to the output and load. Inc ease the amplitude and
f equency by co esponding knobs as necessa y.
Step 7.
Always stop the ope ation of the gene ato by HV ON/OFF switch. Afte that, you
can switch off the gene ato by the powe switch. Afte a long time of ope ation at
high pulse amplitude and f equency, please allow fans to otate seve al minutes in
idle mode fo cooling.
TRIGGERING OF THE GENERATOR
The gene ato can ope ate in inte nal and exte nal t igge ing ope ation modes.
Internal triggering
The inte nal t igge ing mode is set when the INT/EXT button is pushed back. Red
LED on the button continuously lights on, indicating the inte nal t igge ing mode.
The exte nal t igge ing pulse gene ato is not equi ed, and continuous o bu st
ope ation mode can be implemented. Output pulses epetition ate can be adjusted
by FREQUENCY egulation knob within 1 Hz … 101 kHz. P ess this knob and
hold it fo one second fo ente ing into NUMBER-OF-PULSES adjusting egime.
The fou -digit indicato would sta t to flash. Set the equi ed numbe of pulses in
the bu st within 1 to 10000. P ess and hold the knob fo one second again to etu n
back to FREQUENCY adjusting egime. The gene ato ope ates in bu st mode if
User manual o NPG-10/100k (NPG-10/100kN) 11

the set numbe of pulses is less than the set f equency, othe wise, it is in
continuous mode. The complete lists of p eset f equencies and numbe of pulses in
the bu st a e p esented in Appendix A.
External triggering
Exte nal t igge ing mode is set by p essing INT/EXT latching push button. Red
LED on the button lights off, indicating the exte nal t igge ing mode. The
gene ato is t igge ed by the ising edge of the exte nal t igge ing pulse applied to
BNC type SYNC IN connecto . Please use a coaxial cable and t igge ing
gene ato with 50 Ohm impedances. Recommended t igge ing pulse amplitude
and width a e +5 V and 1 µs. Red LED on INT/EXT button blinks with 1 Hz
f equency in case of successful t igge ing. The delay between the t igge ing pulse
f ont and the output pulse (inte nal gene ato delay) is about 1 µs. Typical jitte
(RMS) is 1 ns.
 The maximum allowable pulse epetition ate and the numbe of pulses
within the bu st a e limited by inte nally set FREQUENCY and NUMBER
OF PULSES pa amete s. Please set the equi ed values by FREQUENCY
knob.
The gene ato can ope ate in bu st enable mode also. Long t igge ing pulse
gene ates a bu st of pulses with epetition ate set by FREQUENCY pa amete .
The exte nal t igge ing pulse fed to SYNC IN connecto wo ks as enable signal in
this case. HV pulses a e gene ated continuously until the level of the t igge ing
pulse becomes low.
The single pulse ope ation is available in the case of exte nal t igge ing mode
only.
Fig.3 – Fig.10 show the va ious bu sts of the pulses fo med in the exte nal
t igge ing mode.
Triggering test ode
Push and hold fo one second the PULSE ENERGY knob to switch into
TRIGGERING TEST mode. HV ON/OFF push button is blocked in this mode,
and HV output pulses a e not gene ated. LED display shows 00, which means
ze o output powe . T igge ing sequence f om inte nal and/o exte nal sou ce goes
to SYNC OUT connecto and can be egiste ed by the exte nal oscilloscope. This
mode is useful to check the t igge ing sequence, especially in complicated
ope ation egimes. Push and hold fo one second the PULSE ENERGY knob one
mo e time fo etu ning back to the no mal ope ation mode.
MEGAIMPULSE LTD. 12

Fig.3. Inte nal t igge ing, bu st mode. FREQUENCY sets 100 kHz epetition ate,
NUMBER OF PULSES sets 7 pulses bu st length. CH2 (g een line) shows
the output pulses on SYNC OUT connecto .
Fig.4. Inte nal t igge ing, bu st mode. FREQUENCY sets 100 kHz epetition ate,
NUMBER OF PULSES sets 60 pulses bu st length. CH2 (g een line)
shows the output pulses on SYNC OUT connecto .
User manual o NPG-10/100k (NPG-10/100kN) 13

Fig.5. Exte nal t igge ing mode. The exte nal t igge ing pulses define the
epetition ate. CH2 (g een line) shows SYNC OUT pulses. CH3 (blue
line) shows the t igge ing pulses fed to SYNC IN connecto .
Fig.6. Exte nal t igge ing, bu st mode. Exte nal t igge ing pulses (CH3, blue line)
set 60 kHz epetition ate and 2 pulses in a bu st. CH2 (g een line) shows
SYNC OUT pulses.
MEGAIMPULSE LTD. 14 MEGAIMPULSE LTD. 14

Fig.7. Exte nal t igge ing, bu st enable mode. FREQUENCY pa amete sets
50 kHz epetition ate within a bu st, SYNC IN t igge ing pulse du ation
(CH3, blue line) defines the bu st length of 25 pulses.
Fig.8. Exte nal t igge ing, bu st enable mode. Two SYNC IN pulses (CH3, blue
line) define two bu sts of 10 pulses each. FREQUENCY pa amete sets
100 kHz f equency within the bu sts.
User manual o NPG-10/100k (NPG-10/100kN) 15

Fig.9. Exte nal t igge ing, bu st enable mode. The NUMBER OF PULSES
pa amete is set to 8, limits the total numbe of pulses, and educes the
length of the second bu st to 3 in spite of a longe exte nal t igge ing pulse.
Fig.10. Exte nal t igge ing, bu st enable mode. The pai s of SYNC IN pulses
(CH3, blue line) set the pai bu sts of output pulses (CH2, g een line).
MEGAIMPULSE LTD. 16

SYNC OUT PULSE
NPG-10/100k (NPG-10/100kN) gene ato has BNC type output connecto fo
SYNC OUT pulses. The SYNC OUT pulse amplitude is 3 V on 50 Ohm load and
5 V on high impedance load. The pulse width is 400 ns.
The oscillog am of SYNC OUT pulse (Channel 2, cyan line) is shown in Fig.11.
Channel 1 is the output HV pulse, which is a sou ce of st ong inte fe ence.
The efo e, one can see the noise on the oscillog am at the moment of the output
pulse gene ation. The delay between the ising edge of the t igge ing pulse and the
output pulse is about 1 µs.
Fig.11. Oscillog am of SYNC OUT pulse (Channel 2, cyan line). The pulse
amplitude is 3 V on 50 Ohm load and 5 V on high impedance load. The pulse
width is 400 ns. The delay between the ising edge of the t igge ing pulse and the
high voltage output pulse is about 1 µs.
User manual o NPG-10/100k (NPG-10/100kN) 17

OVERHEAT MODE
NPG-10/100k (NPG-10/100kN) pulse gene ato has ove heating p otection
system. The long-time ope ation with high amplitude and high epetition ate
and/o at high ambient tempe atu e may lead to the ove heating of the gene ato .
OVERHEAT LED lights on in this case, and the gene ato stops the ope ation.
HV ON/OFF push button is tu ned off automatically and disabled. Please stay the
gene ato in idle mode fo seve al minutes, and allow the fans to cool it.
OVERHEAT LED would light off when the tempe atu e dec eases and etu ns
within the safe ange. The gene ato is eady fo the ope ation again.
MEGAIMPULSE LTD. 18