Method and apparatus for aligning a charged particle beam

Claim 2

Apparatus for aligning a beam of charged particles with a section of an elongated passageway provided with a transverse wall having a beam aperture through which said beam passes, said wall being effective to emit X-rays when impinged by said charged particles, said beam alignment apparatus comprising: a set of Xray detectors with collimators, said collimators being so aligned as to pass X-rays only if they come from certain portions of said wall with which said collimators are aligned, and signal processing means which compares the signals from the various Xray detectors to ascertain which edge portion of the beam aperture is impinged by an excessive amount of said charged particles and therefore emitting an excessive amount of X-rays, and beam deflecting means responding to said signal processing means so as to equalize the signal strength received by all of said X-ray detectors thereby to align said beam in said aperture.

Claim 3

Beam alignment apparatus according to claim 1 including means for determining the total X-ray intensity received from all of said X-ray detectors, and beam focusing means responsive to the total X-ray intensity so as to minimize the total X-ray intensity thereby passing the greatest part of said beam through said beam aperture.

Claim 6

A charged particle beam generator comprising a body member having an evacuated chamber and a passageway leading from said chamber outwardly of said body member, means in said chamber generating and projecting a beam of charged particles through said passageway, a chamber wall member in said passageway, said wall member being provided with first and second wall surfaces spaced longitudinally along the path of said beam of particles, said wall member having an aperture extending between and opening outwardly of said first and second wall surfaces, said first wall surface being on the side of said wall member toward said generating means and effective to emit X-rays as a consequence of the impingement thereon of said charged particles, beam adjusting means adjacent said beam of particles and actuatable to alter the path of said beam of particles, X-ray responsive means, X-ray selecting means selectively transmitting certain of said X-rays produced by a first portion of said first wall surface to said X-ray responsive means and preventing transmission of X-rays produced by other portions of said first wall surface from reaching said X-ray responsive means, and control means operatively connecting said X-ray responsive means with said beam adjusting means, said control means being effective actuate said beam adjusting means to alter the path of said beam of particles in a direction to minimize the magnitude of said X-rays which are received by said X-ray responsive means.

Claim 7

A charged particle beam generator comprising a body member having an evacuated chamber and a passageway leading from said chamber outwardly of said body member, means in said chamber generating and projecting a beam of charged particles through said passageway, a chamber wall member in said passageway, said wall member being provided with first and second wall surfaces spaced longitudinally along the path of said beam of particles, said wall member having an aperture extending between and opening outwardly of said first and second wall surfaces, said first wall surface being on the side of said wall member toward said generating means and effective to emit X-rays as a consequence of the impingement thereon of said charged particles, beam adjusting means adjacent said beam of particles and actuatable to alter the path of said beam of particles, X-ray responsive means, X-ray selecting means selectively transmitting certain of said X-rays produced by a first portion of said first wall surface to said X-ray responsive means and preventing transmission of X-rays produced by other portions of said first wall surface from reaching said X-ray responsive means, and control means operatively connecting said X-ray responsive means with said beam adjusting means, said control means being effective actuate said beam adjusting means to alter the path of said beam of particles in a direction to minimize the magnitude of said X-rays which are received by said X-ray responsive means.

Claim 8

The combination of claim 4 including a plurality of said X-ray responsive means and a plurality of said X-ray selecting means individually associated with said X-ray responsive means, said X-ray selecting means selectively transmitting certain of said X-rays produced by individual portions of said first wall surface, said X-ray responsive means being coupled to said control means, said control means being effective to actuate said beam adjusting means in response to a change in the magnitude of the X-rays produced by said individual portions of said first wall surface to alter the path of said beam of particles to minimize the magnitude of X-rays received from said individual portions of said first wall and thereby center the path of said beam of particles in said aperture.

Claim 9

The combination of claim 4 in which said beam adjusting means alters the path of said beam by changing the direction of said path of said beam relative to said aperture.

Claim 10

The combination of claim 4 in which said beam adjusting means alters the path of said beam by focussing said beam of charged particles relative to said aperture.

Claim 11

The combination of claim 4 in which said beam adjusting means alters the path of said beam by focussing and changing the direction of said beam to minimize the total magnitude of said charged particles which impinge on said individual portions of said first wall.

Claim 12

The combination of claim 4 in which said X-ray selecting means is a collimator located in said passageway adjacent said first wall surface, said collimator having a passageway therethrough and positioned between said first portion of said first wall surface and said X-ray responsive means.