Gas Breakdown

DC to 1 us for air

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Gas	Relative Breakdown Strength
Air	1.0
Nitrogen	1.0
SF₆	2.7
Freon	2.5
Hydrogen	0.5
30% SF₆, 70% air by volume	2.0

Paschen's Law

V=f(pd)

Gas	pd_crit (Torr-cm)	V(pd_crit) Volts
Air	0.567	327
Argon	0.9	137
Oxygen	0.70	450
Helium	4.0	156

Liquid Breakdown

t=time that the pulse is above 63% of peak voltage (usec)
A= stressed area (cm2)
d=gap between electrodes
E=Electric field (MV/cm)

Transformer Oil

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for DC operation 40 kV/in

Water

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Solid Dielectric Properties

Material	Dielectric Constant 60 hz		Dielectric Constant 1 Mhz		Delectri Strength (V/mil) on .1 in
Material	e	tan delta	e	tan delta	Delectri Strength (V/mil) on .1 in
Aluminum Oxide	8.80	3.3(-4)	8.8	320	320
Barium Titanate	1250	.056	1143	.0105	75
Soda-Borosilicate Glass	4.97		4.84	3.6(-3)	400
Epoxy (Epon RN-48)	4.5	.05	3.52	.0142	800
Polycarbonate	3.17	.009	2.96	.01	400
Acrylic	4.0	3.5	2.55	.009	570
Polyimide	3.4	.002	??	.003	570
Polyvinyl Chloride	3.2	.0115	2.88	.016	400
PTFE(Teflon)	2.10	<5(-4)	2.10	<2(-4)	550
Nylon	8	4.10	3.40	.04	350
Polyethylene	2.26	<2(-4)	2.10	<2(-4)	450
Polypropylene	2.55	<5(-4)	2.55	<5(-4)	650
Paper	3.3	.010	2.99	.038	200

Above formula from Pulse Power Formulary by R.J. Adler, North Star Research