IPRS 83828

6 July 1983

USSR Report



Vol. 17, No. 3, May-June 1983



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JPRS 83828

6 July 1983


Space Brococy AND Aerospace MEDICINE Vol. 17, No. 3, May-June 1983

Translation of the Russian-language bimonthly journal KOSMICHESKAYA 2IOLOGIYA I AVIAKOSMICHESKAYA MEDITSINA published in Moscow by [zdatel'stvo "Meditsina”.

CONTENTS Combined, Local and Chenical Radioprotection During Spaceflights ..... l Solar Cosmic Radiation and Radiation Hazard of Spaceflights .......... 7 Studies of Characteristics of Solar Cosmic Radiation on Meteor

Satellites “eee eee eee neee oeeeeeeoe ee eer eeeeeeeeeeeeeeeeeeeeeeeeeeeeee 15

Evaluation of Statistical Characteristics of Solar Cosmic Radiation Flares in 20th and 2lst Cycles of Solar Activity ...cccscceceseccees 22

Some Distinctions Referable to Amino Acid Levels in Blood of Cosmonauts Who Participated in 185-Day Flight ....cccecceceseccccees 30

Myoelectric Activity of the Rat Duodenum Under Hypokinetic Conditions. 38

Energetic Reactions in Rat Skeletal ‘fuscles After Flight in Cosmos-1129 Biosatellite ne ft @Peeee eff ft ee © *eereeeeenereeneeeneeeneneneeeeeeee 42

General Patterns of Bone Atrophy in the Absence of Load on Skeleton . 48

Hemodynamic Distinctions Related to Different Models of Experimental Hypokinesia ....... ses eencesoss TeTTTTT TT ccccccccce oo« 60

Structural and Functional Changes in Human Erythrocytes and

Leukocytes Related to Seven-Day Immersion Hypokinesia ..... eccccccce 65 Investigation of Coronary Circulation of Pilots During Flights ...... 71 Diagnosing Fatigue in Flight Personnel According to Cardiodynamic Data 77

-a- [III - USSR - 20H S&T]

rifect of Tranquilizers on Motivation Elements and Tactics of

Uperator Performance “ee eeteeeeneeeneeeneeneeeteeeneeeeeteeeneeeeeeeeeeeeeeeeee#ee#e®

Optimization of Process of Storing Housefly Pupae for Utilization of waste in Biological Life-Support Systems eeeteeoeoeeeeeeeee eee eeeeeee

Lstimates ot Cosmic Radiation Doses in Near-Earth Orbits With Apogee up to 1000 km During Period of Solar Inactivity ..cccceccceccccvcvecs

Expediency of Using Personal Dosimeters for Effective Doses During Manned Spacef lights *oeeeeneneeent#eeneeneeeeneneeneeeeeeeeeneeeeeeeeeee#e

Sarly Determination of Parameters of Proton Flux From Solar Flares on the Basis of Radio-Burst Data eee ee eeeeeeeereeeeeeeeeeeeeeeeeeeeeees

Classification of Regions of Solar Activity Based on Methods of Pattern Recognition Theory e*eeesteeeeneteneeeneteeeneeeneeeneeeneeeetee#ee

Simulat ion of Space Form of Notion Sickness *eeeneeeneeneeeneeneeneeneneeneneeeeee Evaluat ion of Effect of 70 dB Noise on Man *oenereneeee *eenreeenteeeeneeeeee ef

‘Modified Rebreathing Method for Determination of Cardiac Output with Increasing EL. ercise Loads *eeereentes3eereeerk#hieeefePerePerenereeeeeeee#eneneneeeeee #

Effects of Dihydroergotamine and Sydnocarb on Man's Orthostatic Stability With Antiorthostatic Hypokinesia ...ccccccsceccvscccsessecs

‘torpholozical Composition of Human Blood and Cytochemical Reactions of Leukocytes as Related to Long-Term Exposure to Low Concentrations

of Ammonia “er eoeeeeeeeeeneneeeneeneeeeeeneeeeeeneeeneeeneneneeneeeteeeneeeneneeeeeeee

Bilateral Galvanization of Labyrinths Used to Simulate Changes in Vestibular Afferentation in WeightlessneSS .....ceeeecesesesvevees

Seventh All-Union Conference on Space Biology and Aerospace Medicine ..

Abstracts of Articles Filed With the All-Union Scientific Research Institute of Medical and Medicotechnical Information .....ccceeeveees















Fngiish title

Russian title


Publishing house

Place of publication

Date of publication

Signed to press





Vol 17, No 3, May-Jun 1983



O. G. Gazenko



May-June 1983

6 April 1983


"Kosmicheskaya biologiya i aviakosmicheskaya meditsina", 1983



Moscow KOSMICHESKAYA BIOLOGIYA I AVIAKOSMICHESKAYA MEDITSINA in Russian Vol 1/7, No 4, May-Jun 33 (manuscript received 21 May 82) pp 4-8

[Article by V. I. Yefimov, S. K. Karsanova and V. S. Shashkov]

[English abstract from source] This paper summarizes studies of the combined protection of dogs exposed to acute high energy proton irradiation at a dose of 490 rad. The chemical radio- protector--mexamine--was injected intramuscularly at a dose of 10 mg/kg o. \tministered per os at a dose of 75 mg/kg. During the exposure .4.5% of bone marrow was shielded. The dose behind the shielding was 250 rad. The combined use of mexamine ad- ministered per os and partial bone marrow shielding provided better protection, whereas either type of protection applied separately proved inefficient.

[Text] The desire to enhance protection against radiation, with due considera- tion of available means of drug (pharmacological) prevention, as well as of

the effect of local (physical) shielding led to investigation of variants of combined protection of the body. The intent was to obtain a potentiated (additive) radioprotective effect.

Already after the first studies of the effects of local shielding [1] and description of radioprotective agents [2], efforts were made to combine the latter with local shielding of the body in order to enhance the overall radioprotective effect [3-6]. In subsequent years, interest rose in the

study of combined protection in view of determination of the mechanisms of action of radioprotective substances on the body, appearance of new protective agents and expansion of research on postradiation recovery and local shielding. nfforts were made to explain the additive effect when a protective agent (or agents) was combined with partial shielding of the body. The thesis was ad- vanced that the outcome of radiation damage from total-body, let alone sub- total, exposure (shielding of part of the body) in corresponding dose ranges depends on the damage to, preservation and restoration of the population of stem cells of critical systems (bone marrow and intestine). This made it possible to analyze the protective effect of radioprotective agents, as well as of shielding, on the ce!lular level [7, 8].

late, quite a tew experimental studies have been published, which were pur- fon small laboratory animals exposed to y= and x-radiation, as well as radi-

ition trom neutrons, where radioprotective agents combined with local shielding vere used. Although the experiments were quite heterogeneous with respect to conditions, chotce of protective factors and combinations, enhancement of the


radioprotective effect was unquestionable [9-15].

In a large series of experiments [16-18], studies were made of the possibility of using shielding of different thickness, width and localization, combined with preradiation administration of cystamine, aminoethylisothiuronium, mexa- mine or a mixture of protective agents, to protect albino rats exposed to y- radiation or high-energy protons in doses of 650-1300 rad. Protection was also enhanced when agents were given in reduced (as compared to conventional) dosage and combined with "ineffective" shielding, i.e., when local dose to the ihnielded region (head or abdomen) constituted about 40% (260-400 rad) of the total exposure dose. While only 2.7-6.3% of the animals survived with use of protective agents and almost 10% survived when the head was shielded, the survival rate was 36-82% when mexamine or cystamine was combined with local shielding. Combined protection was 1.4-2.0 times more effective than

shielding alone, when the abdominal region was shielded so that, in addition

to intestinal loops, hemopoietic tissue (three lumbar vertebrae and half the spleen) was shielded. The results of the studies revealed that the efficacy

ol combined protection depends largely on radiation dosage (form of radiation damaye), localization of shielding, radiosensitivity of tissues (bone marrow

or intestine) in the irradiated field, as well as which radioprotective agent

is used,

[n the opinion of P. P. Saksonov [19], the potentiating effect of using reduced doses of protective agents combined with "ineffective" shielding of a circum- scribed part of the body could be of basic reievance to development of combined protection for use in spaceflights.

The results of experiments performed on small laboratory animals, which are of theoretical interest and have practical implications, served as grounds to investigate this method of protection in experiments on dogs. Moreover, the lack of information in the literature about large mammals or of data concerning the protective effect of mexamine on dogs exposed to high-energy protons, which are among the most important components of cosmic radiation, prompted us to conduct such experiments.


In our experiments we used 73 dogs (males and females), most of whom weighed

7-9 ke. The synchrocyclotron of the Joint Institute of Nuclear Energy* jn Dubna

was used to deliver 240 MeV protons. The dogs received a dose of 400 rad.

Dose rate was 0.3-1.2 rad/s. We shielded the pelvic region of the dogs with lead blocks 10 cm wide, 10 cm thick and 20 cm high. About 14.5% of all active bune marrow was contained in the shielded region (~15% of total body mass) [20]. Radiation conditions were so selected as to obtain 250 rad under the shield, *Translator's note: This institute is listed as Joint Institute of Nuclear Research in U. S. reference material.

5 -

Wiile the rest ot the body (about 857) received 425 rad.* In all instances,

wan tissue absorbed dose was 400 rad,

nine (o=nethoxytryptamine hydrochloride) was given in a dosaye of 75 mg/kg dy weivht (sealed to base) through a catheter into the stomach in the form of lution 20-25 min belore irradiation, or by intramuscular injection in a losaee of LO me/ky 10-12 min before exposure, The animals were kept under observation tor 45 days after trradlation. Observation included examination the animals, weighing them, testing peripheral blood on the 3d, 7th, LOth, h, 20th, 25th, 30th and 45th postradiation days using conventional methods.

Results and Discussion

\dministration of a protective agent per os or by intramuscular injection was tolerated satisfactorily when given in the indicated dosage. After irradiation, all of the animals (controls and protected) developed acute radiation sickness with similar siyns. External signs of disease appeared in the absolute majority of doys after a latency pertod of 9-12 days. The animals died from the hemo- poietic syndrome of acute radiation sickness. The outcome of irradiation is listed in Table l.

lable I. Survival of experimental dogs after acute irradiation from high-energy prot ONS

a —<—— -——— ——--< - ee eee +

NUMBER OF MST, SURVIVAL Group ANIMAL GROUP ANIMALS DEATHS 1N DAYS RATE ft ae GROUP | CONTROL 23 23 13,42°0,4 9 0 : 16 14 *0,6 2,0 4 MEXAMINE PER OS 7 7 reety “es MEXAMINE PER OS "a0 ' SLD ING | 7 17,9% 1,95 36,5 ) ME XAMINE IM 10 10 14,120,97 0) " MEXAMINE IM + SHIELOING 6 by 18,2~1,8 0

—_ = ee o—_— a - —-

Table 1 shows that when the dose delivered to the shielded bone marrow region was 250 rad only 12.57% of the animals survived (2 out of 16 dogs). At the same time, mean survival time (MST) of dogs in this group was reliably longer than the MST for control animals (P<0.05). Thus, while 50% of the control dogs expired by the 14th day, only ~7% of those protected with shielding sur- vived (1 out of 14 dogs).

Mexamine given per os (75 mg/kg) or intramuscularly (10 mg/kg) did not increase the survival rate of irradiated animals: in both instances all protected dogs died. With the combined use of mexamine per os followed by shielding, 36.47

aM, A. Sychkov and A. [. Portman monitored irradiation and dosimetry. We wish to thank them for their assistance in the experiments.

of the dogs survived, With use of intramuscular : injections and shielding (6th group), although the survival rate did not rise the MST had a a tendency toward increasing, as compared t ee dogs who were either given mexamine or shielded (5th and 2d groups).

- -

| In all experimental groups of dogs there was

| | a decrease in body weight. By the 15th post- | radiation day, their weight dropped by an

| | = average of 7-14%.

} | «


? ust

3.0 =

| ~ Analysis of cellular composition of peripheral | blood revealed that leukopenia developed in

protect ed

x all dogs (Table 2). We see from the data } - ¢ listed in Table 2 that, already on the 3d day, ~ leukocyte count dropped by more than 50% in all groups of dogs. On the 15th day leukopenia was the most marked in all animals. In protected dogs, leukocyte count was always somewhat higher at this time than in the control (by 1.7-3 times). On the 15th post- radiation day, leukocyte count was appreciably higher only in animals given mexamine per os at the rate of 75 mg/kg and protected with shielding (4th group), as compared to control dogs and those given mexamine (3d group) or on which a shield was used (2d group). No analogous finding was demonstrable in dogs given mexamine by intramuscular injection in a dosage of 10mg/kg with subsequent use of shielding (6th group).

ana Mem)



* 0.04 - 0,07 15 =0,14 =0,12

| 0,57 0,47


in control 0.53

Ob = 0,12



count (thousands/mna ;



1,12=0,0 0,7:

1.320,14 0,420,1


leukocyte protons 21 “> ~~!


1,.0= 0,08 14"0,1 0 70,13 1,120 0,1

17 | 0,8

h-enery, 4

There was equally intensive restoration of peripheral blood leukocytes after the 15th day in surviving dogs. By the 45th day, leukocyte count reached 80-85% of the initial value in all of these dogs.

3,4=0,29 3,92 0,28

3,520.3! 2,620,24





0,38 7

INITIAL NUMBER OF CELLS "O17 i 0 8,92 0,4 90,0

8,0= 0,36

Rb Ss

In all experimental groups of dogs, erythro- cyte count began to drop appreciably only Starting on the 7th postradiation day. Maximum erythropenia (2.5-4.0 million/mm’) was observed on the 15th (among dogs that expired) and 20th (survived) days. Already by the 30th day, erythrocyte count rose appreciably in the latter. On the 45th day it constituted ~80Z

of the base level.


Changes in total peripheral blood irradiation from his

1M IM +



9 “-~-«


These results indicate that after acute irradiation with high-energy protons in absolutely lethal doses (400 rad), which







l 2

4 5

fe the paneytopenic syndrome of acute radiation sickness, the death rate itlmost 9O% anmony doys with Local (physical) shielding of “14.5% of bone arrow in the body (it this region receives a dosage of 250 rad). Apparently, in this case, there is virtually complete loss of compensatory capabilities in tue silelded bone marrow region ci these animals. Preventive administra- jon of mexamine in the tested doses (10 mg/kg by intramuscular injection or

/5 mg/kg per os) also had virtually no effect on the general outcome of irradiation. At the same time, according to our findings, administration of the protective agent per os combined with subsequent shielding of bone marrow,

which was aimed at preserving the "critical" pool of hemopoietic stem cells

4,, potentiated the radioprotective effect and was considerably more effective than a similar combination with intramuscular injection of the protective agent. Since protection of hemopoiesis is of first and foremost significance to the outcome of the hemopoietic form of acute radiation sickness, it can be concluded that protection with mexamine of hemopoietic stem cells [7] together with cells preserved by shielding during irradiation cause synergism of protection ind increase the probability of survival of irradiated dogs.

Thus, on the basis of data in the literature and the results of our experiments,

we can conclude that investigation of the combined use of radioprotective agents and local shielding (including the basic possibility of obtaining an additive protective etfect in large mammals also, in particular dogs) could be not only of scientific, but practical significance. It is imperative to conduct studies in this direction systematically and purposefully in order to solve the problem of mechanism of combined protection, validate optimum variants of such protection and determine the feasibility of practical use, including application to space radiobiology and medicine.


l. Jacobson, L. 0., Marks, R., Robson, M. et al., J. LAB. CLIN. MED., Vol 34, 1949, pp 1538-1543.

2, Bacq, Z. M. and Herve, A., SCHWEIZ. MED. WSCHR., Vol 82, 1952, pp 1018-1020.

3. Bethard, W. F. and Jacobson, L. 0., quoted by L. 0. Jacobson in "Radiobiology," ed. by A. Hollender, Moscow, 1960, p 307.


4. Swift, M. N., Taketa, S. T. and Bond, V. P., FED. PROC., Vol 11, 1952, p 153.

Maisin, J., Lambert, G., Mandaic, M. et al., NATURE, Vol 171, 1953, p 9/71. 6. Maisin, J., Maisin, G. and Dunzhicn, A., in "Voprosy radiobiologii" [Problems of Radiobiology], Moscow, 1956, pp 249-276.

7. Abdul', Yu. A., “Study of Radioprotective Effect of Some Chemical Agents on Hemopoietic Stem Cells," author abstract of candidatorial dissertation, Leningrad, 1977.

3. Strelin, G. S., "Regenerative Processes in Development and Fradication of Radiation Damage," Moscow, 1978.


baurkaya, V. S., in "Meditsinskaya primatologiya" [Medical Primatology], (bilisi, 1967, pp 259-263.

Rkusanov, A. M., in "Aviatsionnaya i kosmicheskaya meditsina" [Aviation and Space Medicine], Moscow, Vol 2, 1969, pp 188-189.

Alvukiova, L. N., in "Problemy porazheniya zheludochno-kishechnogo trakta pri radiatsiounykh vuzdeystviyakh" [Problems of Damage to the Gastro- intestinal Tract Aftec Exposure to Radiation], Moscow, 1970, pp 43-44.

verdlov, A. G., "Biological Effects of Neutrons and Chemical Protection," Leningrad, 1974,

Kravchenko, T. A., Avetisov, G. M. and Ovakimov, V. G., MED. RADIOL., No 6, 1975, pp 70-73.

Barkaya, V. S., Torua, R. A., Zeytunyan, K. A. et al., in "Modelirovaniye patologicheskikh sostoyaniy cheloveka" [Models of Human Pathological States], Moscow, Vol 2, 1977, pp 280-285.

McLaughlin, M. M., Krebs, A. T., Grenan, M. M. et al., RADIAT. RES., Vol 31, 1967, p 657.

Razgovorcv, 8. L., Saksonov, P. P., Antipov, V. V. et al., in "Problemy xosmicheskoy biologii" [Problems of Spacc Biclogy], Moscow, Vol 14, 1971, pp 175-185.

Razgovorov, B. L. and Antipov, V. V., in "Kosmicheskaya biologiya i aviakosmicheskaya meditsina" [Space Biology and Aerospace Medicine], Moscow--Kaluga, 1972, pp 285-288.

Gaydamakin, N. A. and Razgovorov, B.L., "Sbornik nauch. rabot Volgograd. med. in-ta"™ [Collection of Scientific Works of Volgograd Medical Institute], Vol 27, 1975, pp 77-81.

Saksonov, P. P., in "Osnovy kosmicheskoy biologii i meditsiny" [Fundamentals of Space Biology and Medicine], Moscow, Vol 3, 1975, pp 317-347.

Nevskaya, G. F., "Role of Critical Organs in Nonuniform Acute Irradiation,’

' author abstract of doctoral dissertation, Moscow, 1974.


Moscow KOSMICHESKAYA BIOLOGIYA IL AVLAKOSMICHESKAYA MEDITSINA in Russian Vol 1/7, No +, May-Jun 83 (manuscript received 14 May 82) pp 8-13


[Article by L. I. Miroshnichenko]

‘English abstract from source] Present-day data on the spectrum of solar radiation in the source and near the f£arth are discussed as applied to the radiation safety of crewmembers and electronics onboard manned and unmanned spacecraft. It is shown that the

slope of the solar radiation spectrum changes (flattens) in the

low energy range. Quantitative information about absolute solar radiation fluxes near the Earth is summarized in relation to the most significant flares of 1956-1978. The time-related evolution of the solar radiation spectrum in the interplanetary space is des- cribed in quantitative terms (as illustrated by the solar flare

of 28 September 1961). It is indicated that the nonmonotonic energy dependence of the transport path of solar radiation in the interplanetary space should be taken into consideration. It is demonstrated that the diffusion model of propagation can be verified using solar radiation measurements in space flights.

[Text] 1. General characteristics and difficulties of the problem. Cosmic solar radiation (SCR) is among the first and foremost sources of radiation hazard from fast charged particles in the orbits of modern manned space complexes (MSC) and unmanned spacecraft (SC). This radiation is gene- rated by solar flares and consists essentially of protons with energy of 1,210" eV. Appearance of SCR near earth cannot be predicted with sufficient accuracy as yet, although there are several methods that permit evaluation of the ditferent characteristics of radiation (time of particle arrival on earth, maximum flux, spectrum indicator and others).

From the standpoint of assuring radiation safety of crews and electronic equip- ment of MSC and SC, the range of «,*~20-500 MeV is of the greatest interest. Quantitative information about the shape of the spectrum at the source (in the sun's atmosphere), absolute particle flux, time and space evolution (dynamics) of particle spectrum in the course of an entire solar proton event (SPE) is needed for accurate assessment of the hazard created by SCR,as well as for planning and conducting experiments in space.

\t the present time, there is no systematic theory or even detailed phenomenolo- ‘ileal intormattion about the behavior of an SPE from the time of its veneration

to the time of recording it. Acceleration theory is alternative: 1) with Jarious base conditions (dilferent mechanisms of accelerations), tne estimated ectraum of accelerated particles could have the same form (for example, exponential, . ')3 2) a specitic form of observed spectrum, [for example, exponential tunction of hardness ~exp (=-R/R,)] could correspond to different mechanisms of acceleration; 3) to describe the form of the spectrum in different

cnercvy ranges one has to draw upon different mechanisms of acceleration. These contradictions are partially attributable to the insufficient accuracy of eisurements, narrowness of energy ranges that can be submitted to a specific method of observation and methodological flaws in reconstructing the spectrum at the source on the basis of observations near earth [1]. At the same time, there {s reason to maintain [1] that these theoretical difficulties are funda- mental: apparently, there is a combination of accelerating mechanisms at the source which provide for the variable shape of the SCRspectrum with gradual flattening, as we go trom the high-energy segment of the spectrum to the region of lower energies.

the wide diversity of observed time profiles of intensity of solar protons 1iso creates major difficulties in assessing the conditions under which particles exit from the solar corona and propagate in interplanetary space. The energy and space dependence of parameters of propagation leads to substantial distor- tion of the observed spectrum, as compared to the SCRspectrum at the source. In order to build a systematic [consistent] theory ofSCR behavior, we think it is necessary to have models of propagation based on analysis of the time protiles of SCR supplemented by models of acceleration based on analysis of eneray spectra of solar particles. We submit below the most relevant data, in our opinion, about the distinctions of generation of cosmic radiation on the sun, propagation of particles in interplanetary space and evolution of their spectrum (see also the survey in [1]).

2. Spectrum at the source. To date, it has become possible to define source spectra or assess the indicator of the spectrum and integral number of particles with hardness in excess of the specified N,(2R) for 33 instances of SPE in the 1956-1977 period [1]. Figure 1 illustrates spectra for some SPE according to hardness R. These spectra were obtained by different authors,

but in essence by the same method--reconstruction of the spectrum observed near earth with use of some version or other of a diffusion model. The illustrated spectra can be described by one of the following formulas:

D-(R) = DyR- 7, (1) D~ (R) = D,exp(—R’'R,). (2)

Unfortunately, the accuracy of determining spectral parameters D,, y and R,

is low (a factor of ~2 for Do, Ay=t0.5 and AR,~+0.05-0.1 GV); the data of different authors pertaining to the same flare do not always agree, while the applicability of the dif .usion approach prompts justifiable doubt in some cases. Nevertheless, the data in [1] constituted, to some extent, a homogeneous series, since they were obtained only for events where the diffusion approximation was applicable. With these stipulations, they can be used as base data for calculat- ing the main radiation (dose) characteristics of SCR.

a eee 290 1977 6 e k. “WE BD DE NOM HM ww 0 R, GV Figure l. Figure 2. Difterential spectra of hardness of Integral spectra of hardness of solar solar protons for SPE's in 1956-1969 protons and electrons for a series of lL) SPE on 23 Feb 1956-W SPE's in 1976-1977. Rp and Re-- 2) same on 23 Feb 1956=M hardness in MV units for protons and }) 15 Nov 1960-' electrons (top and bottom scales, 4) 23 Jan 1967-<M respectively)

») 23 May 1967=™

6) 19 Nov 1961=-M

7) 25 Sep 1961-W

3) 23 Oct 1962-M

9) 16 Jul 1959-W LO) 22 Aug 1958-W ll) 3 Sep 1960-B and 25 Feb 1969-B 12) 15 Nov 1960-B and 28 Jan 1967=-B 13) 18 Jul 1961-W 14) 4 May 1960-B 15) 28 May 1967-B 16) 30 Nar 1969-B

1-4) proton spectra for SPE's on 13 Apr 1977, 12 Oct 1977, 17 Dec 1976 and 9 Oct 1977, respectively

5-9) electron spectra for SPE's on 24 Sep 1977, 12 Oct 1977, 17 Dec 1976, 6 Oct 1977 and 4 Jan 1977

Analysis of the data in [1] enabled us to detect some distinctions in the spectra exceeding the range of the above ambiguities. In particular, it was tound that in the exponential expression (1) the spectra have a variable slope, and they become flatter (y diminishes) in the range of low R's. On the other hand, if the range under consideration is rather broad, exponential expression (2) alone is also inapplicable. This can be well-seen on the example of the events on 23 Feb 1956 and 28 Jan 1967, and it is also confirmed (as a trend) for a number of other SPE's.

The above distinction of the spectra can be interpreted on the basis of a model, in which acceleration is effected by electric field E, which appears upon separation of the neutral current layer, combined with a betautron mechanism.

In this case, the source spectrum is described by the following formula [1]:

D-(R) = Dy (1 R/R*)~*. (3)

whet ois the normalizing constant, while parameters R* and are determined Prem observations. With R/R*® #1, formula (3) is reduced to tormula (1), and with k/I 1, it is approximated quite accurately by equation (2).

lhe lack of selectivity with respect to kind of particles, effective acceleration ot not only protons, but electrons, the close link with the physics of solar ilares (through field E) are the obvious advantages of the model in [l]. A similar approach (combination of Fermi and betatron mechanisms) was used,

for example in [2], to describe the spectrum of electrons that was reconstructed trom observations of electromagnetic radiation of the flare on 4 Aug 1972. With», = 0.91-L00 MeV, the spectrum at the source has a variable slope (it becomes flatter with €& “1 MeV).

At the same time, models of the [l, 2] type also have flaws, which are related to the ambiguity of conditions in the region of acceleration. Moreover, we

also consider quite problematic consideration of the effect of conditions of particle exit from the solar corona, particularly in the range of low energies. in this regard, the indications that, for flares in the heliolongitude range

of 20-380°W, the differential spectrum of protons with €& = 4-80 MeV at time *),, near earth apparently reflects the source spectrum [3] merits attention, and

the spectrum parameter changes from flare to flare within a narrow range-- 2.0-3.1. These conclusions were derived from analysis of SC data for 125 SPE's.

On the other hand, data are cited in [4] about the spectra of electrons with

, 0.03-3 MeV and protons with €y = 0.1-500 MeV, which were obtained for time ‘max according to near-earth observations of 19 SPE's with the help of the SC's Forecast-|"Prognoz"] 5, 6, Venus-["Venera"] 11, 12, and IMP-7, IMP-8 in 1976-1979. Typically, the proton spectra for all events presented a more complex appearance than electron spectra, and the proton spectra become more sloped in the range

of low energies (experiencing 1-2 breaks). This effect is attributed [4] to adiabatic slowing of protons in the course of their propagation in interplanetary space. In our opinion, stricter validation of the obtained form of spectrun,

for both protons and electrons, can be obtained with the model in [1].

After analyzing the data in [4] on the basis of formula (2), we arrived at the conclusion that the spectra of protons and electrons for hardness on a semi- loparithmic scale have the appearance of smooth curves. This is apparent in Figure 2, which illustrates the spectra of several SPE's differing appreciably in intensity (the spectra for the other events iiave an analogous shape). If

the spectra described in [4] are indeed similar to the spectra at the source, it can be stated that their shape is not in contradiction to the acceleration model (2). Let us note that strict validation of the variable form of SCR spectrum at the source would be of basic significance to assessment of radiation character- istics of SCR.

$. Propagation and evolution of SCR spectrum. In the course of propaga- tion in heterogeneous magnetic fields of the solar atmosphere and interplanetary space, the source spectrum should undergo deformation (with the exception, per- haps, of some limited range of energies [3, 4]). Deformation occurs, specifically, due to the energy dependence of parameters of propagation in the corona (diffusion, convection and drift, see, for example, [5, 6]) or in interplanetary


we (transport range tor seatter A (e,) [1l, 2]. Beeause of the dynamic nature interplanetary environment, its marked time and space heterogeneity, t kinetic theory ot propagation cannot, for the time being, explain the fliversity of observed time profiles of SCR,in spite of its well-developed twire. tor this reason, in many instances, one must give preference to menological theory to tnterpret SPE characteristics, which is based on fhe tensor conception of coetficient of spatial diffusion «;°+. Some of the , ments of this tensor equel zero, while among the others we can single out ertain dominant components corresponding, for example, to transport range ilony the interplanetary magnetic field (IMF). The value of (A); can be either omparable to .., the range across the IMF (isotropic diffusion), or exceed it significantly (anisotropic diffusion).

fable l. 0

as a tunction of ¢€,

j | aL 10? io* |

| | is es es = 400

\ a 4 int? The R.1gh | 1Q'2 m. 10!


Table 2. Ro as a tunction of hardness range

100" a _

| \ MY | Kaas , | ' by j . MV | MV | - | - Figure 3. | | 400-1000 16I | 1.15 208 Characteristic parameter of exponential : Re me | is a spectrum Ry as a function of time for ; | 700 1000! 197 | Lo 247 SPE on 28 Sep 1961 in several ranges of hardness AR. The numbers near the curves

correspond to range numbers in Table 2.

fo identify |"diagnose"] an SPE and describe evolution of the spectrum and time profile of SCR, it is important to take into consideration the nonmonotonic nature of function A(e,): in the interval of ec, = 30-300 MeV the range has a liftuse minimum (for more details see [l1]). None of the propagation models in explain the nature of the minimum as yet. However, for practical purposes, t is important to note that the value of A can undergo 5-6-fold change from are to flare at the same energy in the range of 10-500 MeV. We can use following (Table 1) as approximate values of A(e,), in accordance with he data in [1].

n recent years it has been possible to clearly demonstrate an interesting eature in the time dynamics of the SCR spectrum observed near earth, namely, that characteristic hardness of the spectrum Rp is a function of t when it is expressed exponentially, D(R)~exp(-R/R,). In Figure 3, function R,(t) was plotted for data referable to the flare on 28 Sep 1961 for several ranges of hardness AR (Table 2).

| i t


icure $ shows that R»(*) becomes a smooth declining function of * only

when it siarts to have ua threshold value t> = 1 and 1.4 h, respectively, for ranges | and 3-4 (vertical dash lines). With tt, , function R,(+) gradually approaches a certain asymptotic value R.,~ (horizontal dash lines). The vertical dot and dash line shows time ¢ = 5 h, for which there is the experimental value

R » 210 MV (averaged for the range of 400-1000 MV), which conforms well with

the estimated value Ry = 208 MV [7]. Analogous behavior of R,(+) was found in (8) for protons with ¢.<24 MeV (R210 MV) during the SPE's on 7 Sep, 13 Sep and

17 Sep 1973.

The values of Roasg in Figure 3 apparently correspond to the established state of “Kk tlux, when the shape of the spectrum undergoes virtually no change with

weneral decline of intensity. We were impressed by the fact that the value of Roa g depends on the width of the AR interval considered. This means that the exponent tor description of the spectrum is merely a convenient form of approxima- tion, and the narrower a given ({R interval, the more precise it is.

Results ot the type cited in [7, 8] can be used for operational evaluation of marnitude and dynamics of irradiation from SCRaccording to ongoing readings aboard the SC. Moreover, they indicate a possible route for checking experimentally the diffusion models. It is also apparent from the foregoing, as well as previous findings [7], that for practical estimates it is expedient to tirst sive a forecast of the time course of differential intensities of SCR »y a certain time * on the basis of the results of current measurements, and then to reconstruct the spectrum by means of interpolation according

to the intensity values obtained by that time.

Figure 4. Integral energy spectra of SCR according to observations near earth at different stages of SPE (solid lines) and possible extra- polation in adjacent energy ranges (dash lines)

1-4) event on 23 Feb 1956, initial phase, 5.00 UT, 20.00 UT and late phase, respectively

6) 15 Jul 1959, 00.30 UT before storm

7) same, 10.46 UT during storm

8) 12 Nov and 15 Nov 1960, tmax

9) 12 Jul 1961, tax

10) 18 Jul 1961, tmax

11) 22 Nov 1977, tmax

12) 7 May 1978, artificial earth satellite,


-max 13) same, SNMtstrat., tmax

Dot-dash line 14 corresponds to equality of energy densities of SCR and geomagnetic field (87/87 = (pV*/2) of SCR.

4, SCRspectra near earth. Different methods of observing SCR(on earth's surface, in the stratosphere, in orbits of artificial earth satellites, along

thus becomes possible to

earth is quite extensive and d been summarized o1 propagation of SCR evolution of

tf SC in interplanetary space) easured eheryles,. it r | data about spectra obtained ryved SCRopectra near irf ir, [1]j), but has not yet iry to comprehend the physics of trum, proper calculation of ir dose characteristics. One of the yllow the dynamics of range of ivh-energy SPE, ferent methods.

the strony he solid

oa ,



ransyes, the

‘rey densities and

it possible t


by different methods.


tasks in this area



O OVE! lap the tually Intormation about


Verse °

to the

5 ee? * extent its

geophysical effects of SCR and estimation of ot change in absolute flux and shape of SCR spectrum over a energies (1-10° MeV) and throughout the event for a concrete, iccording to the results of synchronous measurements by

research is to

We examined data about near-earth spectra for several of

geomagnetic field

(to the

est SPE's as the first step toward performing such a task (Figure 4). in Figure 4 show the actual spectra observed by some method ind the dash lines their possible extrapolation to adjacent energy dot-dash line corresponds to the condition of equality of SCR left and above this line,


enerswy density exceeds that of the geomagnetic field, so that SCR can



. i 43a: f shows that iriable slope with considered enervies.

most powerful of

; 1} 4 siay >

a ierc L

appreciable flattening of the spectrum in the range of low ¢,. that the strongest SPE's of the current, 2lst cycle of 1977 and 7 May 1978) were appreciably weaker than the

ry ute f indicate al rlar activity (22 N

the observed >


invade the magnetosphere to a certain depth).

ty over

like source spectra, demonstrate a lattening in the region of low

a wide range of

The data in Figure 4 confirm the known fact that the



the observed SPE's was the flare on 23 Feb 1956. enough, even in this instance, the geomagnetic effect of SCK (collective of SCRon the geomagnetic field) was apparently insignificant, due to the


The data in

“CRot the 19th cycle (23 Feb 1956, 12 Nov and 15 Nov 1960); SPE's were even

weaker in the 20th c ‘on?


arguments have been

ycle [1].

advanced [9]

Although the