UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                                (Amendment No.)*

                                 IONATRON, INC.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                          Common Stock, $.001 par value
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    462070103
                                    ---------
                                 (CUSIP Number)

                                 March 17, 2006
                                 --------------
                      (Date of Event which Requires Filing
                               of this Statement)



Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

                  [  ]  Rule 13d-1(b)
                  [X ]  Rule 13d-1(c)
                  [  ]  Rule 13d-1(d)


*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

                                  Page 1 of 9




---------------------------                               ----------------------
CUSIP No. 462070103               13G                     Page  2  of 9 Pages
---------------------------                               ----------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Advisors, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) [ ]
                                                                (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       5,020,381 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.9% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 2 of 9




---------------------------                               ----------------------
CUSIP No. 462070103               13G                     Page  3  of 9 Pages
---------------------------                               ----------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Management, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) [ ]
                                                                (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       5,020,381 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.9% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 3 of 9





---------------------------                               ----------------------
CUSIP No. 462070103               13G                     Page  4  of 9 Pages
---------------------------                               ----------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Associates, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) [ ]
                                                                (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Anguilla, British West Indies
--------------------------------------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       4,975,181 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            4,975,181 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           4,975,181 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.9% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 4 of 9



---------------------------                               ----------------------
CUSIP No. 462070103               13G                     Page  5  of 9 Pages
---------------------------                               ----------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Steven A. Cohen
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) [ ]
                                                                (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           United States
--------------------------------------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       5,020,381 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           5,020,381 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.9% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           IN
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 5 of 9





Item 1(a)           Name of Issuer:
                    --------------

                    Ionatron, Inc.

Item 1(b)           Address of Issuer's Principal Executive Offices:
                    -----------------------------------------------

                    3590 East Columbia Street
                    Tucson, Arizona 85714

Items 2(a)          Name of Person Filing:
                    ---------------------

                    This statement is filed by: (i) S.A.C. Capital Advisors,
                    LLC, ("SAC Capital Advisors") with respect to shares of
                    common stock, par value $0.001 per share ("Shares") of the
                    Issuer beneficially owned by S.A.C. Capital Associates, LLC
                    ("SAC Capital Associates") and S.A.C. MultiQuant Fund, LLC
                    ("SAC MultiQuant"); (ii) S.A.C. Capital Management, LLC,
                    ("SAC Capital Management") with respect to Shares
                    beneficially owned by SAC Capital Associates and SAC
                    MultiQuant; (iii) SAC Capital Associates with respect to
                    Shares beneficially owned by it; and (iv) Steven A. Cohen
                    with respect to Shares beneficially owned by SAC Capital
                    Advisors, SAC Capital Management, SAC Capital Associates and
                    SAC MultiQuant.

Item 2(b)           Address of Principal Business Office:
                    ------------------------------------

                    The address of the principal business office of (i) SAC
                    Capital Advisors, and Mr. Cohen is 72 Cummings Point Road,
                    Stamford, Connecticut 06902, (ii) SAC Capital Management is
                    540 Madison Avenue, New York, New York 10022 and (iii) SAC
                    Capital Associates is P.O. Box 58, Victoria House, The
                    Valley, Anguilla, British West Indies.

Item 2(c)           Citizenship:
                    -----------

                    SAC Capital Advisors and SAC Capital Management are Delaware
                    limited liability companies. SAC Capital Associates is an
                    Anguillan limited liability company. Mr. Cohen is a United
                    States citizen.

Item 2(d)           Title of Class of Securities:
                    ----------------------------

                    Common Stock, $0.001 par value

Item 2(e)           CUSIP Number:
                    ------------

                    462070103

Item 3              Not Applicable


                                  Page 6 of 9




Item 4              Ownership:
                    ---------

                    The percentages used herein are calculated based upon the
                    Shares issued and outstanding as of March 14, 2006 as
                    reported on the Issuer's annual report on Form 10-K filed
                    with the Securities and Exchange Commission by the Issuer
                    for the fiscal year ended December 31, 2005.

                    As of the close of business on March 21, 2006:

                    1. S.A.C. Capital Advisors, LLC
                    (a) Amount beneficially owned: 5,020,381
                    (b) Percent of class: 6.9%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 5,020,381
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    5,020,381

                    2. S.A.C. Capital Management, LLC

                    (a) Amount beneficially owned: 5,020,381
                    (b) Percent of class: 6.9%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 5,020,381
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    5,020,381

                    3. S.A.C. Capital Associates, LLC

                    (a) Amount beneficially owned: 4,975,181
                    (b) Percent of class: 6.9%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 4,975,181
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    4,975,181

                    4. Steven A. Cohen

                    (a) Amount beneficially owned: 5,020,381
                    (b) Percent of class: 6.9%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 5,020,381
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    5,020,381

                    SAC Capital Advisors, SAC Capital Management and Mr. Cohen
                    own directly no Shares. Pursuant to investment agreements,
                    each of SAC Capital Advisors and SAC Capital Management
                    share all investment and voting power with respect to the



                                  Page 7 of 9



                    securities held by SAC Capital Associates and SAC
                    MultiQuant. Mr. Cohen controls each of SAC Capital Advisors
                    and SAC Capital Management. By reason of the provisions of
                    Rule 13d-3 of the Securities Exchange Act of 1934, as
                    amended, each of SAC Capital Advisors, SAC Capital
                    Management and Mr. Cohen may be deemed to own beneficially
                    5,020,381 Shares (constituting approximately 6.9% of the
                    Shares outstanding). Each of SAC Capital Advisors, SAC
                    Capital Management and Mr. Cohen disclaim beneficial
                    ownership of any of the securities covered by this
                    statement.

Item 5              Ownership of Five Percent or Less of a Class:
                    --------------------------------------------

                    If this statement is being filed to report the fact that as
                    of the date hereof the reporting person has ceased to be the
                    beneficial owner of more than five percent of the class of
                    securities, check the following. [ ]

Item 6              Ownership of More than Five Percent on Behalf of Another
                    --------------------------------------------------------
                    Person:
                    ------

                    Not Applicable

Item 7              Identification and Classification of the Subsidiary Which
                    ---------------------------------------------------------
                    Acquired the Security Being Reported on By the Parent
                    -----------------------------------------------------
                    Holding Company:
                    ---------------

                    Not Applicable

Item 8              Identification and Classification of Members of the Group:
                    ---------------------------------------------------------

                    Not Applicable

Item 9              Notice of Dissolution of Group:
                    ------------------------------

                    Not Applicable

Item 10             Certification:
                    -------------

         By signing below the signatory certifies that, to the best of his
knowledge and belief, the securities referred to above were not acquired and are
not held for the purpose of or with the effect of changing or influencing the
control of the issuer of the securities and were not acquired and are not held
in connection with or as a participant in any transaction having that purpose or
effect.

                                  Page 8 of 9





                                    SIGNATURE
                                    ---------

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated:  March 22, 2006

S.A.C. CAPITAL ADVISORS, LLC


By:    /s/ Peter Nussbaum
       -------------------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


S.A.C. CAPITAL MANAGEMENT, LLC


By:    /s/ Peter Nussbaum
       -------------------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


S.A.C. CAPITAL ASSOCIATES, LLC


By:    /s/ Peter Nussbaum
       -------------------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


STEVEN A. COHEN


By:    /s/ Peter Nussbaum
       -------------------------------------
Name:   Peter Nussbaum
Title:  Authorized Person





                                  Page 9 of 9