Cymer, Inc.

The United States of America As Represented by the United States

Science Research Laboratory, Inc.

Other

The United States of America As Represented by the Department of Energy

Advanced Pulse Power Technologies, Inc.

Daniel L Birx

William N Partlo

Richard M Ness

Igor Vladimirovich Fomenkov

Paul C Melcher

Daniel Anthony Rothweil

Edward G Cook

Brett D Smith

Don G Ball

Richard L Sandstrom

Louis L Reginato

I Roger Oliver

Palash P Das

Tom A Watson

Stuart L Anderson

James K Howey

Alex P Ivaschenko

Jean-Marc Hueber

Stephan T Melnychuk

John L Miller

Vladimir A Kulgeyko

Phillip A Arnold

John E Rauch

A multi-stage magnetic modulator provides a pulse train of &plusmn;40 kV electrical pulses at a 5-7 kHz repetition rate to a metal vapor laser. A fractional turn transformer steps up the voltage by a factor of 80 to 1 and magnetic pulse compression is used to reduce the pulse width of the pulse train. The transformer is fabricated utilizing a rod and plate stack type of construction to achieve a high packing factor. The pulses are controlled by an SCR stack where a plurality of SCRs are electrically connected in parallel, each SCR electrically connected to a saturable inductor, all saturable inductors being wound on the same core of magnetic material for enhanced power handling characteristics.

High power solid state laser modulator

A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the source or active gas. Preferably the electrodes are configured co-axially with the anode on the axis. The anode is preferably hollow and the active gas is introduced through the anode. This permits an optimization of the spectral line source and a separate optimization of the buffer gas. Preferred embodiments present optimization of capacitance values, anode length and shape and preferred active gas delivery systems are disclosed. Preferred embodiments also include a pulse power system comprising a charging capacitor and a magnetic compression circuit comprising a pulse transformer. A heat pipe cooling system is described for cooling the central anode.

Plasma focus light source with improved pulse power system

A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at repetition rates of 1000 Hz or greater and at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the source or active gas. A fourth generation unit is described which produces 20 mJ, 13.5 nm pulses into 2 &pgr; steradians at repetition rates of 2000 Hz with xenon as the active gas. This unit includes a pulse power system having a resonant charger charging a charging capacitor bank, and a magnetic compression circuit comprising a pulse transformer for generating the high voltage electrical pulses at repetition rates of 2000 Hz or greater.

Plasma focus light source with tandem ellipsoidal mirror units

A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. A working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at voltages high enough to create electrical discharge between the electrodes to produce very high temperature, high density plasma pinch in the working gas providing radiation at the spectral line of the active gas. An external reflection radiation collector-director collects radiation produced in the plasma pinches and directs the radiation in a desired direction. In a preferred embodiment the active gas is lithium and the buffer gas is helium and the radiation collector-director is coated with the material used for the electrodes. A good choice for the material is tungsten. In a second preferred embodiment the buffer gas is argon and lithium gas is produced by vaporization of solid or liquid lithium located in a hole along the axis of the central electrode of a coaxial electrode configuration. Other preferred embodiments utilize a conical nested debris collector upstream of the radiation collector-director.

Plasma pinch high energy with debris collector

A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the active gas. A blast shield positioned just beyond the location of the high density pinch provides a physical barrier which confines the pinch limiting its axial elongation. A small port is provided in the blast shield that permits the radiation but not the plasma to pass through the shield. In a preferred embodiment a surface of the shield facing the plasma is dome-shaped.

Plasma focus high energy photon source with blast shield

A gas discharge laser capable of operating at pulse rates in the range of 4,000 Hz to 6,000 Hz at pulse energies in the range of 5 mJ to 10 mJ or greater. Important improvements over prior art designs include: (1) a laser chamber having a gas flow path with a gradually increasing cross section downstream of the discharge electrodes to permit recovery a large percentage of the pressure drop in the discharge region, (2) a squirrel cage type fan for producing gas velocities through the discharge region of more than 76 m/s and capable of continuous trouble-free operation for several months, (3) a heat exchanger system capable of removing in excess of 16 kw of heat energy from the laser gas (4) a pulse power system capable of providing precisely controlled electrical pulses to the electrodes needed to produce laser pulses at the desired pulse energies in the range of 5 mJ to 10 mJ or greater at pulse repetition rates in the range of 4,000 Hz to 6,000 Hz or greater and (5) a laser beam measurement and control system capable of measuring pulse energy wavelength and bandwidth on a pulse-to-pulse laser with feedback pulse-to-pulse control of pulse energy and wavelength.

Extreme repetition rate gas discharge laser

A high pulse repetition frequency (PRF) plasma gun is provided, which gun inlets a selected propellant gas into a column formed between a center electrode and a coaxial outer electrode, utilizes a solid state high repetition rate pulse driver to provide a voltage across the electrodes and provides a plasma initiator at the base of the column, which is normally operative when the driver is fully charged. For preferred embodiments, the initiator includes a sold state simulated RF driver, the outputs from which are applied to electrodes affixed in an insulator and producing a high voltage field at a surface of the insulator which forms part of the base end of the column. The plasma expands from the base end of the column and off the exit end thereof. When used as a thruster, for example in space applications, the driver voltage and electrode lengths are selected such that the plasma for each pulse exits the column at approximately the same time the voltage across the electrodes reaches zero, thereby maximizing the thrust. When used as a radiation source, the voltage and electrode length are selected such that the plasma exits the column when the current is maximum. The plasma is magnetically pinched as it exits the, column, thereby raising the plasma temperature, energizing an element in fluid state applied to the pinch, for example through the center electrode, to provide radiation at a desired wavelength. The element may also be applied to the pinch by forming at least one of the center and outer electrodes of a sintered powder refractory metal, the element in fluid form being wicked into the electrode. The plasm gun parameters can be selected to achieve a desired wavelength, which may for example be within the EUV or VUV band. The pulse driver preferably provides a high voltage spike followed by a lower voltage, longer duration sustainer signal, most of the driver energy being provided by the sustainer signal. The plasma gun of this invention, which is capable of operating at PRFs in the range of approximately 100 Hz to in excess of 5,000 Hz, may also be used in other applications.

Plasma gun and methods for the use thereof

A high pulse rate pulse power source for supplying controlled high energy electrical pulses at rates of 2000 Hz or greater. The source includes a pulse generating circuit including a charging capacitor, a solid state switch and a current limiting inductor. Pulses generated in the pulse generating circuit are compressed in at least two pulse compression circuits and a step-up pulse transformer increases peak voltage to at least 12,000 volts. A very fast regulated power supply is provided for charging the charging capacitor in less than 400 microseconds and a pulse control system including a programmed processor controls the charging of the charging capacitor to an accuracy of less than about one percent at a rate of at least 4000 charges per second. In a preferred embodiment capable of operating at pulse rates of 2000 to 4000 Hz or greater, water cooling of the saturable inductors is provided.

High pulse rate pulse power system with liquid cooling

This invention relates to a plasma focus source for generating radiation at a selected wavelength, the invention involving producing a high energy plasma sheathe which moves down an electrode column at high speed and is pinched at the end of the column to form a very high temperature spot. An ionizable gas introduced at the pinch can produce radiation at the desired wavelength. In order to prevent separation of the plasma sheathe from the pinch, and therefore to prolong the pinch and prevent potentially damaging restrike, a shield of a high temperature nonconducting material is positioned a selected distance from the center electrode and shaped to redirect the plasma sheathe to the center electrode, preventing separation thereof. An opening is provided in the shield to permit the desired radiation to pass substantially unimpeded.

Plasma focus radiation source

A high pulse rate pulse power source for supplying controlled high energy electrical pulses at rates of 2000 Hz or greater. The source includes a pulse generating circuit including a charging capacitor, a solid state switch and a current limiting inductor. Pulses generated in the pulse generating circuit are compressed in at least two pulse compression circuits and a step-up pulse transformer increases peak voltage to at least 12,000 volts. A very fast regulated power supply is provided for charging the charging capacitor in less than 400 microseconds and a pulse control system including a programmed processor controls the charging of the charging capacitor to an accuracy of less than about one percent at a rate of at least 2000 charges per second.

High pulse rate pulse power system with fast rise time and low current

A high pulse repetition frequency (PRF) plasma gun is provided, which gun inlets a selected propellant gas into a column formed between a center electrode and a coaxial outer electrode, utilizes a solid state high repetition rate pulse driver to provide a voltage across the electrodes and provides a plasma initiator at the base of the column, which is normally operative when the driver is fully charged. For preferred embodiments, the initiator includes RF driven electrodes. The plasma expands from the base end of the column and off the exit end thereof. When used as a thruster, for example in space applications, the driver voltage and electrode lengths are selected such that the plasma for each pulse exits the column at approximately the same time the voltage across the electrodes reaches zero, thereby maximizing the thrust. When used as a radiation source, the voltage and electrode length are selected such that the plasma exits the column when the current is maximum. The plasma is magnetically pinched as it exits the column, thereby raising the plasma temperature, energizing an element in gas state applied to the pinch, for example through the center electrode to provide radiation at a desired wavelength. The plasm gun parameters can be selected to achieve a desired wavelength, which may for example be within the EUV band. In particular, the pinch temperature is preferable high enough to ionize a significant portion of the gas applied to the pinch to its single election state, thereby producing radiation at the wavelength having maximum intensity If a longer, lower-intensity wavelength is desired, filtering of at least higher intensity, shorter wavelengths concurrently generated is desirable. Temperature at the pinch can also be selected to control the type of emission to minimize output angle of the radiation. The plasma gun of this invention, which is capable of operating at PRFs in the range of approximately 100 Hz to in excess of 5,000 Hz, may also be used in other applications.

A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. A working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at voltage high enough to create electrical discharge between the electrodes to produce very high temperature, high density plasma pinch in the working gas providing radiation at the spectral line of the active gas. An external reflection radiation collector-director collects radiation produced in the plasma pinches and directs the radiation in a desired direction. In a preferred embodiment the active gas is lithium and the buffer gas is helium and the radiation-collector is coated with the material used for the electrodes. A good choice for the material is tungsten. In a second preferred embodiment the buffer gas is argon and lithium gas is produced by vaporization of solid lithium located in a hole along the axis of the central electrode of a coaxial electrode configuration.

Plasma focus high energy photon source

A high pulse rate pulse power source for supplying controlled high energy electrical pulses at rates of 2000 Hz or greater. The source includes a pulse generating circuit including a charging capacitor, a solid state switch and a current limiting inductor. Pulses generated in the pulse generating circuit are compressed in at least two pulse compression circuits and a step-up pulse transformer increases peak voltage to at least 12,000 volts. A very fast regulated resonant power supply is provided for charging the charging capacitor in less than 400 microseconds and a pulse control system including a programmed processor controls the charging of the charging capacitor to an accuracy of less than about one percent at a rate of at least 2000 charges per second.

High pulse rate pulse power system with resonant power supply

A simple, novel pulse power circuit is described, which improves the net coupling efficiency of a pulse power system used to drive a gas discharge laser, and minimizes current reversal and electrode erosion. The circuit, in accordance with an embodiment of the present invention, incorporates a saturable inductor. Contrary to conventional saturable inductor configurations, in which the saturable inductor is either not saturated or is presaturated in a reverse direction, in the present circuit the saturable inductor is presaturated in the forward direction. The saturable inductor is inserted between the final stage capacitor of a pulse power circuit and a gas discharge load, where it allows forward current but effectively blocks reverse current through the load. Elimination of reverse discharge current reduces electrode erosion and improves discharge chamber life.

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Oakley, CA, United States of America

Daniel L Birx