Abstract

Pulsed, megawatt laser power levels at 3371 Å from nitrogen gas require the formation of a high density plasma of high electron temperature in the first few nanoseconds of gaseous breakdown. This has been obtained from a laser tube powered by a pulse forming network in the form of a low impedance, parallel plate transmission line. Another low impedance, parallel plate transmission line, charged to 30 kV is used to pulse charge the pulse forming line by means of a synchronized, multiple spark gap switch. The pulse forming transmission line terminates in a continuous high voltage electrode which runs parallel to the axis of the tube, i.e., in the direction of the light beam. The finite, nonzero time required for the gas in the laser tube to break down, permits (a) pulse charging this line to voltages many times larger than the dc breakdown voltage of the nitrogen in the laser tube, and (b) the placement of the switch in the circuit where its impedance does not limit the rate of rise of current during the laser excitation process. Furthermore, it is shown that decreasing the impedance of the pulse forming line increases the laser output power, when the current in the laser circuit is not limited by circuit inductance.

© 1968 Optical Society of America

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References

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  1. H. G. Heard, Nature 200, 667 (1963).
    [CrossRef]
  2. E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965); D. A. Leonard, Appl. Phys. Lett. 7, 4 (1965).
    [CrossRef]
  3. J. D. Shipman, A. C. Kolb, IEEE J. Quant. Electron. QE-2, 298 (1966).
  4. J. D. Shipman, Appl. Phys. Lett 10, 1 (1967).
    [CrossRef]
  5. M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
    [CrossRef]
  6. R. G. Bennett, F. W. Dalby, J. Chem. Phys. 31, 434 (1959).
    [CrossRef]
  7. S. I. Andreev, M. P. Vanyukov, Sov. Phys.–Tech. Phys. 6, 8 (1962);S. I. Andreev, B. I. Orlov, Sov. Phys.–Tech. Phys. 10, 8 (1966).
  8. D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
    [CrossRef]
  9. F. Llewellyn-Jones, Ionization and Breakdown in Gases (John Wiley & Sons, Inc., New York, 1957), p. 128 ff.

1967 (1)

J. D. Shipman, Appl. Phys. Lett 10, 1 (1967).
[CrossRef]

1966 (2)

M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
[CrossRef]

J. D. Shipman, A. C. Kolb, IEEE J. Quant. Electron. QE-2, 298 (1966).

1965 (2)

D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
[CrossRef]

E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965); D. A. Leonard, Appl. Phys. Lett. 7, 4 (1965).
[CrossRef]

1963 (1)

H. G. Heard, Nature 200, 667 (1963).
[CrossRef]

1962 (1)

S. I. Andreev, M. P. Vanyukov, Sov. Phys.–Tech. Phys. 6, 8 (1962);S. I. Andreev, B. I. Orlov, Sov. Phys.–Tech. Phys. 10, 8 (1966).

1959 (1)

R. G. Bennett, F. W. Dalby, J. Chem. Phys. 31, 434 (1959).
[CrossRef]

Altman, D. E.

M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
[CrossRef]

Andreev, S. I.

S. I. Andreev, M. P. Vanyukov, Sov. Phys.–Tech. Phys. 6, 8 (1962);S. I. Andreev, B. I. Orlov, Sov. Phys.–Tech. Phys. 10, 8 (1966).

Bennett, R. G.

R. G. Bennett, F. W. Dalby, J. Chem. Phys. 31, 434 (1959).
[CrossRef]

Dalby, F. W.

R. G. Bennett, F. W. Dalby, J. Chem. Phys. 31, 434 (1959).
[CrossRef]

DeTemple, T. A.

M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
[CrossRef]

Geller, M.

M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
[CrossRef]

Gerry, E. T.

E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965); D. A. Leonard, Appl. Phys. Lett. 7, 4 (1965).
[CrossRef]

D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
[CrossRef]

Heard, H. G.

H. G. Heard, Nature 200, 667 (1963).
[CrossRef]

Kolb, A. C.

J. D. Shipman, A. C. Kolb, IEEE J. Quant. Electron. QE-2, 298 (1966).

Leonard, D. A.

D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
[CrossRef]

Llewellyn-Jones, F.

F. Llewellyn-Jones, Ionization and Breakdown in Gases (John Wiley & Sons, Inc., New York, 1957), p. 128 ff.

Neal, R. A.

D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
[CrossRef]

Shipman, J. D.

J. D. Shipman, Appl. Phys. Lett 10, 1 (1967).
[CrossRef]

J. D. Shipman, A. C. Kolb, IEEE J. Quant. Electron. QE-2, 298 (1966).

Vanyukov, M. P.

S. I. Andreev, M. P. Vanyukov, Sov. Phys.–Tech. Phys. 6, 8 (1962);S. I. Andreev, B. I. Orlov, Sov. Phys.–Tech. Phys. 10, 8 (1966).

Appl. Phys. Lett (1)

J. D. Shipman, Appl. Phys. Lett 10, 1 (1967).
[CrossRef]

Appl. Phys. Lett. (2)

E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965); D. A. Leonard, Appl. Phys. Lett. 7, 4 (1965).
[CrossRef]

D. A. Leonard, R. A. Neal, E. T. Gerry, Appl. Phys. Lett. 7, 6 (1965).
[CrossRef]

IEEE J. Quant. Electron. (1)

J. D. Shipman, A. C. Kolb, IEEE J. Quant. Electron. QE-2, 298 (1966).

J. Appl. Phys. (1)

M. Geller, D. E. Altman, T. A. DeTemple, J. Appl. Phys. 39, 3639 (1966).
[CrossRef]

J. Chem. Phys. (1)

R. G. Bennett, F. W. Dalby, J. Chem. Phys. 31, 434 (1959).
[CrossRef]

Nature (1)

H. G. Heard, Nature 200, 667 (1963).
[CrossRef]

Sov. Phys.–Tech. Phys. (1)

S. I. Andreev, M. P. Vanyukov, Sov. Phys.–Tech. Phys. 6, 8 (1962);S. I. Andreev, B. I. Orlov, Sov. Phys.–Tech. Phys. 10, 8 (1966).

Other (1)

F. Llewellyn-Jones, Ionization and Breakdown in Gases (John Wiley & Sons, Inc., New York, 1957), p. 128 ff.

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Figures (9)

Fig. 1
Fig. 1

Schematic diagram of a pulsed, nitrogen laser.

Fig. 2
Fig. 2

Gas laser tube and its power source. Component values are: storage line length, 170 cm; width, 107 cm; impedance, 0.10 Ω. Pulse forming line impedance was varied between 0.080 Ω and 0.27 Ω. Storage line transit time, 10 nsec; pulse forming line transit time, 3.5 nsec; switch inductance, 20 nH (estimated).

Fig. 3
Fig. 3

Details of construction of pulse forming line and laser tube.

Fig. 4
Fig. 4

Time histories of (a) voltage pulse on laser VP(t) and (b) corresponding laser output pulse. The two photographs were taken with two Tektronix type 519 oscilloscopes that had been synchronized to have the same starting time and sweep speed. Horizontal time scale is 10 nsec/cm. Vertical scale: (a) laser voltage (9.3 kV/cm); (b) power (2 MW/cm).

Fig. 5
Fig. 5

Equivalent circuit during pulse charging. V0 is the initial voltage of the storage element, the parallel plate line of capacitance Cs. VP(t) is the time varying voltage on the pulse forming capacitance CP. Ls is the inductance of the spark gap switch.

Fig. 6
Fig. 6

Equivalent circuit during current flow through the laser tube. This representation is valid for the first two transits of the pulse forming line after laser gas breakdown. Vb is the voltage on the pulse forming line at the laser tube when the gas breaks down. ZP is the characteristic impedance of the pulse forming line. L is the residual inductance in the pulse forming line and the laser tube. Rg(t) is the time varying resistance of the nitrogen gas in the laser tube.

Fig. 7
Fig. 7

Laser output power as a function of breakdown voltage in nitrogen gas for different values of pulse forming line impedance. Storage line impedance was maintained at 0.10 Ω. The laser was operated in the superradiant mode with one reflecting mirror. Nitrogen pressure was 35 Torr.

Fig. 8
Fig. 8

Laser output power as a function of breakdown voltage in neon gas for different values of pulse forming line impedance. Storage line impedance was maintained at 0.10 Ω. The laser was operated in superradiant mode with one reflecting mirror. Neon pressure was 40 Torr.

Fig. 9
Fig. 9

Typical multipeaked laser pulse. Horizontal scale: Time (10 nsec/cm); Vertical scale: Power (2 MW/cm). The voltage pulse that corresponds to this laser pulse is identical to that shown in Fig. 4(a).

Equations (7)

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I s c = V P / Z P ,
V P ( max ) = E P ( max ) · s ;
Z P = 377 s / w ( ) 1 2 ,
I = E P ( max ) w ( ) 1 2 / 377.
V P ( t ) = { V 0 / [ ( 1 + C P ) / C s ] } ( 1 - cos ω r t ) ,
ω r = [ ( C s + C P ) / C P C s L s ] 1 2 .
V b = L I ˙ ( t ) + Z P I ( t ) + R g ( t ) I ( t ) .

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