US 5,452,069 AGranted

Spark sampling microparticle generator and method

AssigneeVarian Associates, Inc.

InventorsJames T. Arnold, Andrew T. Zander, Elbert S. Lile, Charles B. Cooper, III

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Abstract

A spark sampling microparticle generator device and method providing means to first ionize a gap and then to switch a stabilized and controllable current into and out of said ionized gap to provide extremely high, selectable current density in a sample material in said gap with very fast rise and fall times to ablate said material to form microparticles. A plurality of identical modular circuits containing high frequency power transistors are selectably switchably connected in parallel simultaneously to the gap to achieve current densities which are higher than achievable with a single transistor, thereby obtaining the benefits of the high frequency response without being limited by the current limitations of the available transistors.

Claims13

Dependent claims

In a spark apparatus for ablating sample from a solid material to be analyzed to create microparticles from said material by use of high intensity electrical sparks and to move said microparticles to an analyzer including

(a) means to mount said material to be sampled to said spark apparatus;
(b) means to cause partial ionization in gas in the space between said spark apparatus and said sample;
(c) means to control the electric current flowing in said ionized gas, THE IMPROVEMENT COMPRISING a module including;
(d) means to establish a stabilized current value in a circuit external to said ionized space;
(e) capacitor means to store sufficient energy in said external circuit for one spark pulse wherein said capacitor means charges during the period before said stabilized current is established in said external circuit;
(f) said means to establish a stabilized current comprises means to obtain the energy for said current from said capacitor means;
(g) means to switch said stabilized current from said external circuit to flow into said space containing gas ions, said means to switch for switching said stabilized current into said space containing ions causing further increase in ionization and permitting flow of high current;
and
(h) means to switch said stabilized current out of said space containing ions and back into said external circuit after a predetermined selectable interval.

6 more elements

A spark circuit for generating microparticles comprising:

(a) a sample compartment including a first pointed electrode, and a second electrode;
said second electrode being made from a solid material to be analyzed, said first and second electrode being separated by a space containing a gas;
(b) an ignitor, said ignitor being connected to said first pointed electrode, for providing a high voltage short duration pulse sufficient to ionize said gas in said space between said first and second electrode;
(c) a first transistor power switch having a gate, drain and source;
(d) a capacitor, said capacitor having a first and second terminal;
(e) a string of series connected diodes connected to said first pointed electrode on one end of said string of diodes and to a first terminal of said capacitor and to said drain of said first transistor power switch on the opposite end of said string of diodes;
(f) a DC power supply having positive and negative terminals, said DC power supply being connected to a first terminal of a first current limiting resistor, said positive terminal of said DC power supply being connected to said source of said first transistor power switch and to said second electrode of said sample compartment, said first current limiting resistor having a second terminal;
and
(g) a second transistor power switch having a source, drain and gate, said source of said second transistor power switch being connected to said second terminal of said first current limiting resistor and to said second terminal of said capacitor.

6 more elements

Dependencies are inferred from the claim text.